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1.  Subtyping of Breast Cancer by Immunohistochemistry to Investigate a Relationship between Subtype and Short and Long Term Survival: A Collaborative Analysis of Data for 10,159 Cases from 12 Studies 
PLoS Medicine  2010;7(5):e1000279.
Paul Pharoah and colleagues evaluate the prognostic significance of immunohistochemical subtype classification in more than 10,000 breast cancer cases with early disease, and examine the influence of a patient's survival time on the prediction of future survival.
Immunohistochemical markers are often used to classify breast cancer into subtypes that are biologically distinct and behave differently. The aim of this study was to estimate mortality for patients with the major subtypes of breast cancer as classified using five immunohistochemical markers, to investigate patterns of mortality over time, and to test for heterogeneity by subtype.
Methods and Findings
We pooled data from more than 10,000 cases of invasive breast cancer from 12 studies that had collected information on hormone receptor status, human epidermal growth factor receptor-2 (HER2) status, and at least one basal marker (cytokeratin [CK]5/6 or epidermal growth factor receptor [EGFR]) together with survival time data. Tumours were classified as luminal and nonluminal tumours according to hormone receptor expression. These two groups were further subdivided according to expression of HER2, and finally, the luminal and nonluminal HER2-negative tumours were categorised according to expression of basal markers. Changes in mortality rates over time differed by subtype. In women with luminal HER2-negative subtypes, mortality rates were constant over time, whereas mortality rates associated with the luminal HER2-positive and nonluminal subtypes tended to peak within 5 y of diagnosis and then decline over time. In the first 5 y after diagnosis the nonluminal tumours were associated with a poorer prognosis, but over longer follow-up times the prognosis was poorer in the luminal subtypes, with the worst prognosis at 15 y being in the luminal HER2-positive tumours. Basal marker expression distinguished the HER2-negative luminal and nonluminal tumours into different subtypes. These patterns were independent of any systemic adjuvant therapy.
The six subtypes of breast cancer defined by expression of five markers show distinct behaviours with important differences in short term and long term prognosis. Application of these markers in the clinical setting could have the potential to improve the targeting of adjuvant chemotherapy to those most likely to benefit. The different patterns of mortality over time also suggest important biological differences between the subtypes that may result in differences in response to specific therapies, and that stratification of breast cancers by clinically relevant subtypes in clinical trials is urgently required.
Please see later in the article for the Editors' Summary
Editors' Summary
Each year, more than one million women discover they have breast cancer. Breast cancer begins when cells in the breast's milk-producing glands or in the tubes (ducts) that take milk to the nipples acquire genetic changes that allow them to divide uncontrollably and to move around the body (metastasize). The uncontrolled cell division leads to the formation of a lump that can be detected by mammography (a breast X-ray) or by manual breast examination. Breast cancer is treated by surgical removal of the lump or, if the cancer has started to spread, by removal of the whole breast (mastectomy). Surgery is usually followed by radiotherapy or chemotherapy. These “adjuvant” therapies are designed to kill any remaining cancer cells but can make women very ill. Generally speaking, the outlook (prognosis) for women with breast cancer is good. In the United States, for example, nearly 90% of affected women are still alive five years after their diagnosis.
Why Was This Study Done?
Because there are several types of cells in the milk ducts and glands, there are several subtypes of breast cancer. Luminal tumors, for example, begin in the cells that line the ducts and glands and usually grow slowly; basal-type tumors arise in deeper layers of the ducts and glands and tend to grow quickly. Clinicians need to distinguish between different breast cancer subtypes so that they can give women a realistic prognosis and can give adjuvant treatments to those women who are most likely to benefit. One way to distinguish between different subtypes is to stain breast cancer samples using antibodies (immune system proteins) that recognize particular proteins (antigens). This “immunohistochemical” approach can identify several breast cancer subtypes but its prognostic value and the best way to classify breast tumors remains unclear. In this study, the researchers investigate the survival over time of women with six major subtypes of breast cancer classified using five immunohistochemical markers: the estrogen receptor and the progesterone receptor (two hormone receptors expressed by luminal cells), the human epidermal growth factors receptor-2 (HER2, a protein marker used to select specific adjuvant therapies), and CK5/6 and EGFR (proteins expressed by basal cells).
What Did the Researchers Do and Find?
The researchers pooled data on survival time and on the expression of the five immunohistochemical markers from more than 10,000 cases of breast cancer from 12 studies. They then divided the tumors into six subtypes on the basis of their marker expression: luminal (hormone receptor-positive), HER2-positive tumors; luminal, HER2-negative, basal marker-positive tumors; luminal, HER2-negative, basal marker-negative tumors; nonluminal (hormone receptor-negative), HER2-positive tumors; nonluminal, HER2-negative, basal marker-positive tumors; and nonluminal, HER2-negative, basal marker-negative tumors. In the first five years after diagnosis, women with nonluminal tumor subtypes had the worst prognosis but at 15 years after diagnosis, women with luminal HER2-positive tumors had the worst prognosis. Furthermore, death rates (the percentage of affected women dying each year) differed by subtype over time. Thus, women with the two luminal HER2-negative subtypes were as likely to die soon after diagnosis as at later times whereas the death rates associated with nonluminal subtypes peaked within five years of diagnosis and then declined.
What Do These Findings Mean?
These and other findings indicate that the six subtypes of breast cancer defined by the expression of five immunohistochemical markers have distinct biological characteristics that are associated with important differences in short-term and long-term outcomes. Because different laboratories measured the immunohistochemical markers using different methods, it is possible that some of the tumors included in this study were misclassified. However, the finding of clear differences in the behavior of the immunochemically classified subtypes suggests that the use of the five markers for tumor classification might be robust enough for routine clinical practice. The application of these markers in the clinical setting, suggest the researchers, could improve the targeting of adjuvant therapies to those women most likely to benefit. Furthermore, note the researchers, these findings strongly suggest that subtype-specific responses should be evaluated in future clinical trials of treatments for breast cancer.
Additional Information
Please access these Web sites via the online version of this summary at
This study is further discussed in a PLoS Medicine Perspective by Stefan Ambs
The US National Cancer Institute provides detailed information for patients and health professionals on all aspects of breast cancer (in English and Spanish)
The American Cancer Society has a detailed guide to breast cancer, which includes information on the immunochemical classification of breast cancer subtypes
The UK charities MacMillan Cancer Support and Cancer Research UK also provide detailed information about breast cancer
The MedlinePlus Encyclopedia provides information for patients about breast cancer; Medline Plus provides links to many other breast cancer resources (in English and Spanish)
PMCID: PMC2876119  PMID: 20520800
2.  Androgen Receptor Expression in Breast Cancer in Relation to Molecular Phenotype: Results from the Nurses’ Health Study 
Prior studies have demonstrated that androgen receptor is expressed in many breast cancers, but its expression in relation to the various breast cancer subtypes as defined by molecular profiling has not been studied in detail.
We constructed tissue microarrays from 3,093 breast cancers that developed in women enrolled in the Nurses’ Health Study. Tissue microarray sections were immunostained for estrogen receptor, progesterone receptor, human epidermal growth factor receptor2, cytokeratin 5/6, epidermal growth factor receptor and androgen receptor. Immunostain results were used to categorize each cancer as luminal A or B, HER2 and basal-like. The relationships between androgen receptor expression and molecular subtype were analyzed.
Overall, 77% of the invasive breast carcinomas were androgen receptor positive. Among 2,171 invasive cancers, 64% were luminal A, 15% luminal B, 6% HER2 and 11% basal-like. The frequency of androgen receptor expression varied significantly across the molecular phenotypes (p<0.0001). In particular, androgen receptor expression was commonly observed in luminal A (91%) and B (68%) cancers, but was less frequently seen in HER2 cancers (59%). Despite being defined by the absence of estrogen and progesterone receptor expression and being considered hormonally unresponsive, 32% of basal-like cancers expressed androgen receptor. Among 246 cases of ductal carcinoma in situ, 86% were androgen receptor-positive, but the frequency of androgen receptor expression differed significantly across the molecular phenotypes (p=0.001) and high nuclear grade lesions were less likely to be androgen receptor-positive compared with lower grade lesions.
Androgen receptor expression is most commonly seen in luminal A and B invasive breast cancers. However, expression of androgen receptor is also seen in approximately one-third of basal-like cancers, providing further evidence that basal-like cancers represent a heterogeneous group. Our findings raise the possibility that targeting the androgen receptor pathway may represent a novel therapeutic approach to the management of patients with basal-like cancers.
PMCID: PMC3128675  PMID: 21552212
3.  Receptor-Defined Subtypes of Breast Cancer in Indigenous Populations in Africa: A Systematic Review and Meta-Analysis 
PLoS Medicine  2014;11(9):e1001720.
In a systematic review and meta-analysis, Isabel dos Santos Silva and colleagues estimate the prevalence of receptor-defined subtypes of breast cancer in North Africa and sub-Saharan Africa.
Please see later in the article for the Editors' Summary
Breast cancer is the most common female cancer in Africa. Receptor-defined subtypes are a major determinant of treatment options and disease outcomes but there is considerable uncertainty regarding the frequency of poor prognosis estrogen receptor (ER) negative subtypes in Africa. We systematically reviewed publications reporting on the frequency of breast cancer receptor-defined subtypes in indigenous populations in Africa.
Methods and Findings
Medline, Embase, and Global Health were searched for studies published between 1st January 1980 and 15th April 2014. Reported proportions of ER positive (ER+), progesterone receptor positive (PR+), and human epidermal growth factor receptor-2 positive (HER2+) disease were extracted and 95% CI calculated. Random effects meta-analyses were used to pool estimates. Fifty-four studies from North Africa (n = 12,284 women with breast cancer) and 26 from sub-Saharan Africa (n = 4,737) were eligible. There was marked between-study heterogeneity in the ER+ estimates in both regions (I2>90%), with the majority reporting proportions between 0.40 and 0.80 in North Africa and between 0.20 and 0.70 in sub-Saharan Africa. Similarly, large between-study heterogeneity was observed for PR+ and HER2+ estimates (I2>80%, in all instances). Meta-regression analyses showed that the proportion of ER+ disease was 10% (4%–17%) lower for studies based on archived tumor blocks rather than prospectively collected specimens, and 9% (2%–17%) lower for those with ≥40% versus those with <40% grade 3 tumors. For prospectively collected samples, the pooled proportions for ER+ and triple negative tumors were 0.59 (0.56–0.62) and 0.21 (0.17–0.25), respectively, regardless of region. Limitations of the study include the lack of standardized procedures across the various studies; the low methodological quality of many studies in terms of the representativeness of their case series and the quality of the procedures for collection, fixation, and receptor testing; and the possibility that women with breast cancer may have contributed to more than one study.
The published data from the more appropriate prospectively measured specimens are consistent with the majority of breast cancers in Africa being ER+. As no single subtype dominates in the continent availability of receptor testing should be a priority, especially for young women with early stage disease where appropriate receptor-specific treatment modalities offer the greatest potential for reducing years of life lost.
Please see later in the article for the Editors' Summary
Editors' Summary
Breast cancer is the commonest female tumor in Africa and death rates from the disease in some African countries are among the highest in the world. Breast cancer begins when cells in the breast acquire genetic changes that allow them to grow uncontrollably and to move around the body. When a breast lump is found (by mammography or manual examination), a few cells are collected from the lump (a biopsy) to look for abnormal cells and to test for the presence of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER2) on the cells. The hormones estrogen and progesterone promote the growth of normal breast cells and of ER+ and PR+ breast cancer cells. HER2 also controls the growth of breast cells. The receptor status of breast cancer is a major determinant of treatment options and prognosis (likely outcome). ER+ tumors, for example, are more receptive to hormonal therapy and have a better prognosis than ER− tumors, whereas HER2+ tumors, which make large amounts of HER2, are more aggressive than HER2− tumors. Breast cancer is treated by surgically removing the lump or the whole breast (mastectomy) if the tumor has already spread, before killing any remaining cancer cells with chemotherapy or radiotherapy. In addition, ER+, PR+, and HER2+ tumors are treated with drugs that block these receptors (including tamoxifen and trastuzumab), thereby slowing breast cancer growth.
Why Was This Study Done?
ER+ tumors predominate in white women but the proportion of ER+ tumors among US-born black women is slightly lower. The frequency of different receptor-defined subtypes of breast cancer in indigenous populations in Africa is currently unclear but policy makers need this information to help them decide whether routine receptor status testing should be introduced across Africa. Because receptor status is a major determination of treatment options and outcomes, it would be more important to introduce receptor testing if all subtypes are present in breast cancers in indigenous African women and if no one subtype dominates than if most breast cancers in these women are ER+. In this systematic review (a study that uses pre-defined criteria to identify all the research on a given topic) and meta-analysis (a statistical approach that combines the results of several studies), the researchers examine the distribution of receptor-defined breast cancer subtypes in indigenous populations in Africa.
What Did the Researchers Do and Find?
The researchers identified 54 relevant studies from North Africa involving 12,284 women with breast cancer (mainly living in Egypt or Tunisia) and 26 studies from sub-Saharan Africa involving 4,737 women with breast cancer (mainly living in Nigeria or South Africa) and used the data from these studies to calculate the proportions of ER+, PR+, and HER2+ tumors (the number of receptor-positive tumors divided by the number of tumors with known receptor status) across Africa. The proportion of ER+ tumors varied markedly between studies, ranging between 0.40 and 0.80 in North Africa and between 0.20 and 0.70 in sub-Saharan Africa. Among prospectively collected samples (samples collected specifically for receptor-status testing; studies that determined the receptor status of breast cancers using stored samples reported a lower proportion of ER+ disease than studies that used prospectively collected samples), the overall pooled proportions of ER+ and triple negative tumors were 0.59 and 0.21, respectively.
What Do These Findings Mean?
Although these findings highlight the scarcity of data on hormone receptor and HER2 status in breast cancers in indigenous African populations, they provide new information about the distribution of breast cancer subtypes in Africa. Specifically, these findings suggest that although slightly more than half of breast cancers in Africa are ER+, no single subtype dominates. They also suggest that the distribution of receptor-defined breast cancer subtypes in Africa is similar to that found in Western populations. The accuracy of these findings is likely to be affected by the low methodological quality of many of the studies and the lack of standardized procedures. Thus, large well-designed studies are still needed to accurately quantify the distribution of various breast cancer subtypes across Africa. In the meantime, the current findings support the introduction of routine receptor testing across Africa, especially for young women with early stage breast cancer in whom the potential to improve survival and reduce the years of life lost by knowing the receptor status of an individual's tumor is greatest.
Additional Information
Please access these websites via the online version of this summary at
This study is further discussed in a PLOS Medicine Perspective by Sulma i Mohammed
The US National Cancer Institute (NCI) provides comprehensive information about cancer (in English and Spanish), including detailed information for patients and professionals about breast cancer including an online booklet for patients
Cancer Research UK, a not-for profit organization, provides information about cancer; its detailed information about breast cancer includes sections on tests for hormone receptors and HER2 and on treatments that target hormone receptors and treatments that target HER2 is a not-for-profit organization that provides up-to-date information about breast cancer (in English and Spanish), including information on hormone receptor status and HER2 status
The UK National Health Service Choices website has information and personal stories about breast cancer; the not-for profit organization Healthtalkonline also provides personal stories about dealing with breast cancer
PMCID: PMC4159229  PMID: 25202974
4.  Androgen Receptor Status Is a Prognostic Marker in Non-Basal Triple Negative Breast Cancers and Determines Novel Therapeutic Options 
PLoS ONE  2014;9(2):e88525.
Triple negative breast cancers are a heterogeneous group of tumors characterized by poor patient survival and lack of targeted therapeutics. Androgen receptor has been associated with triple negative breast cancer pathogenesis, but its role in the different subtypes has not been clearly defined. We examined androgen receptor protein expression by immunohistochemical analysis in 678 breast cancers, including 396 triple negative cancers. Fifty matched lymph node metastases were also examined. Association of expression status with clinical (race, survival) and pathological (basal, non-basal subtype, stage, grade) features was also evaluated. In 160 triple negative breast cancers, mRNA microarray expression profiling was performed, and differences according to androgen receptor status were analyzed. In triple negative cancers the percentage of androgen receptor positive cases was lower (24.8% vs 81.6% of non-triple negative cases), especially in African American women (16.7% vs 25.5% of cancers of white women). No significant difference in androgen receptor expression was observed in primary tumors vs matched metastatic lesions. Positive androgen receptor immunoreactivity was inversely correlated with tumor grade (p<0.01) and associated with better overall patient survival (p = 0.032) in the non-basal triple negative cancer group. In the microarray study, expression of three genes (HER4, TNFSF10, CDK6) showed significant deregulation in association with androgen receptor status; eg CDK6, a novel therapeutic target in triple negative cancers, showed significantly higher expression level in androgen receptor negative cases (p<0.01). These findings confirm the prognostic impact of androgen receptor expression in non-basal triple negative breast cancers, and suggest targeting of new androgen receptor-related molecular pathways in patients with these cancers.
PMCID: PMC3914993  PMID: 24505496
5.  Distribution, clinicopathologic features and survival of breast cancer subtypes in Southern China 
Cancer Science  2012;103(9):1679-1687.
Breast cancer research and treatment by different subtypes is an inevitable trend. We investigated the clinicopathologic features and outcomes of different breast cancer subtypes in Southern China. A total of 5809 patients with invasive ductal carcinomas were identified. Immunohistochemical (IHC) markers for estrogen receptor (ER), progesterone receptor (PR), Her2/neu, and Ki-67 proliferation index were used to classify cases into five molecular subtypes. Clinicopathologic characteristics and survival rates were analyzed retrospectively. Of all patients, 31.1% were luminal A subtype, 30.4% luminal B (high Ki-67), 13.1% luminal B (Her2/neu+), 9.0% Her2/neu and 16.5% triple negative subtype. Luminal B (high Ki-67) presented primarily in premenopausal patients with the lowest average age (43.0 years). Her2/neu positive tumors were more closely associated with aggressive features including increased tumor size, positive lymph node status and lymphvascular invasion (LVI). Triple negative subtype was characterized by poorer histologic grade. Her2/neu positive cases had presented the worst 5-year disease-free survival (DFS) and overall survival (OS). Multivariate analyses of OS and DFS suggested that there were different negative prognostic factors for the five subtypes. The benefit of the cyclophosphamide, methotrexate, and 5-fluorouracil (5FU) (CMF) regimen was equal to that of anthracycline-based and Taxane-based regimens for patients with luminal A subtype and triple negative subtype, but inferior to anthracycline-based and Taxane-based regimens for those with two luminal B subtypes and Her2/neu subtype. The prognostic significance of traditional markers may differ among subtypes. This study revealed the distinct clinicopathologic characteristics, systemic therapy benefits, prognostic factors and survival rate among different breast cancer subtypes.
PMCID: PMC3466418  PMID: 22625227
6.  Ki67 Index, HER2 Status, and Prognosis of Patients With Luminal B Breast Cancer 
Gene expression profiling of breast cancer has identified two biologically distinct estrogen receptor (ER)-positive subtypes of breast cancer: luminal A and luminal B. Luminal B tumors have higher proliferation and poorer prognosis than luminal A tumors. In this study, we developed a clinically practical immunohistochemistry assay to distinguish luminal B from luminal A tumors and investigated its ability to separate tumors according to breast cancer recurrence-free and disease-specific survival.
Tumors from a cohort of 357 patients with invasive breast carcinomas were subtyped by gene expression profile. Hormone receptor status, HER2 status, and the Ki67 index (percentage of Ki67-positive cancer nuclei) were determined immunohistochemically. Receiver operating characteristic curves were used to determine the Ki67 cut point to distinguish luminal B from luminal A tumors. The prognostic value of the immunohistochemical assignment for breast cancer recurrence-free and disease-specific survival was investigated with an independent tissue microarray series of 4046 breast cancers by use of Kaplan–Meier curves and multivariable Cox regression.
Gene expression profiling classified 101 (28%) of the 357 tumors as luminal A and 69 (19%) as luminal B. The best Ki67 index cut point to distinguish luminal B from luminal A tumors was 13.25%. In an independent cohort of 4046 patients with breast cancer, 2847 had hormone receptor–positive tumors. When HER2 immunohistochemistry and the Ki67 index were used to subtype these 2847 tumors, we classified 1530 (59%, 95% confidence interval [CI] = 57% to 61%) as luminal A, 846 (33%, 95% CI = 31% to 34%) as luminal B, and 222 (9%, 95% CI = 7% to 10%) as luminal–HER2 positive. Luminal B and luminal–HER2-positive breast cancers were statistically significantly associated with poor breast cancer recurrence-free and disease-specific survival in all adjuvant systemic treatment categories. Of particular relevance are women who received tamoxifen as their sole adjuvant systemic therapy, among whom the 10-year breast cancer–specific survival was 79% (95% CI = 76% to 83%) for luminal A, 64% (95% CI = 59% to 70%) for luminal B, and 57% (95% CI = 47% to 69%) for luminal–HER2 subtypes.
Expression of ER, progesterone receptor, and HER2 proteins and the Ki67 index appear to distinguish luminal A from luminal B breast cancer subtypes.
PMCID: PMC2684553  PMID: 19436038
7.  Molecular breast cancer subtypes and therapies in a public hospital of Northeastern Brazil 
BMC Women's Health  2014;14:110.
The frequencies of molecular breast cancer subtypes vary among different human populations. The Northeastern region of Brazil has a mixed population of African, Indigenous and European ancestry. This retrospective study investigated breast cancer subtypes and applied therapies in a public hospital of Northeastern Brazil.
Data of 633 patients with invasive breast cancer from 2005 to 2011 were obtained from medical records. Status of hormone receptor (HR), HER2 and Ki67 expression index of 269 out of 633 patients were used to define subtypes of Luminal A and B, HER2 and triple negative (TN) breast cancer. Expression index of Ki67 ≥ 14% was applied to distinguish Luminal A from Luminal B subtypes.
Overall, 185 (68.77%) and 132 (49.07%) patients showed positive hormone receptor (HR+) and positive HER2 (HER2+) tumors. The mean age ranged from 53.33 to 58.25 years for patients with tumors of Luminal B and Luminal A subtypes, respectively (p = 0.0182). In general, 67.39% of patients with TN tumors aged over 50 and 19.57% aged between 31 and 40 years (p = 0.0046). The rate of small tumors (T1: ≤ 2.0 cm) varied from 22.73% to 52.46% for TN and Luminal A subtypes (p = 0.0088). The rate of high graded (G3) tumors was increased for HER2 and TN subtypes (35.29% and 34.28%) compared to Luminal A and Luminal B subtypes (3.92% and 12.62%), respectively (p < 0.0001). The five-year survival rate ranged from 92.86% to 75.00%, for Luminal A, HER2 and TN subtypes, respectively (HR: 0.260 to 1.015; 95% CI: 0.043 to 3.594; p = 0.2589). Patients with HER2 positive (HER2+) breast tumors did not receive immunotherapy and chemotherapy application varied from 54.84% to 86.49% for Luminal A and HER2 subtypes, respectively (p = 0.0131).
The results of this study revealed a high percentage of HER2+ breast tumors and an increased rate of patients with TN tumors aged over 50 years. This emphasizes the need for establishing immunotherapy as an additional therapeutic option to improve clinical outcomes for patients with HER2+ tumors and to investigate the risk factors of TN breast cancer.
PMCID: PMC4166019  PMID: 25216732
Invasive breast cancer; Molecular subtypes; Therapeutic opportunities; Population of African; European and Indigenous ancestry; Northeastern Brazil
8.  Folate receptor alpha (FRA) expression in breast cancer: identification of a new molecular subtype and association with triple negative disease 
SpringerPlus  2012;1:22.
Given that several targeted therapies directed towards folate receptor alpha (FRA) are in late stage clinical development, the sensitive and robust detection of FRA in tissues is of paramount importance relative to patient selection, prognosis and prediction. In the present study we undertook an immunohistochemical evaluation of expression of FRA in breast cancer samples using formalin-fixed, paraffin-embedded (FFPE) tissues, primarily invasive ductal carcinomas, using a newly described monoclonal antibody, 26B3. Samples assessed included both tissue microarrays (TMA) and whole tissue sections from archival tissue blocks. Normal breast shows a highly restricted expression of FRA to luminal membrane staining of secretory ductal cells, consistent with FRA secretion into milk. In early stage (stages I-III) invasive ductal carcinomas, FRA staining was observed in approximately 30% of all samples, independent of molecular subtype (estrogen receptor (ER)/progesterone receptor (PR)/human epidermal growth factor receptor type 2 (Her2)). However, FRA expression was shown to associate with ER/PR negative tumors relative to ER/PR positive tumors (p = 0.012) and perhaps more importantly, with triple negative breast cancers (TNBC; p < 0.0001). FRA immunoreactivity was also shown to be retained in stage IV metastatic breast cancer samples from diverse anatomic sites including lymph node and bone. In metastatic breast cancer, FRA was shown to be expressed in 86% of TNBC patients. Taken together, these data suggest that FRA expressing breast cancer represents a novel molecular subtype and, further, may represent a new therapeutic target for this devastating disease.
PMCID: PMC3725886  PMID: 23961352
Folate receptor alpha; FRA; Breast cancer; Triple negative breast cancer; Immunohistochemistry; IHC
9.  DEAR1 Is a Dominant Regulator of Acinar Morphogenesis and an Independent Predictor of Local Recurrence-Free Survival in Early-Onset Breast Cancer 
PLoS Medicine  2009;6(5):e1000068.
Ann Killary and colleagues describe a new gene that is genetically altered in breast tumors, and that may provide a new breast cancer prognostic marker.
Breast cancer in young women tends to have a natural history of aggressive disease for which rates of recurrence are higher than in breast cancers detected later in life. Little is known about the genetic pathways that underlie early-onset breast cancer. Here we report the discovery of DEAR1 (ductal epithelium–associated RING Chromosome 1), a novel gene encoding a member of the TRIM (tripartite motif) subfamily of RING finger proteins, and provide evidence for its role as a dominant regulator of acinar morphogenesis in the mammary gland and as an independent predictor of local recurrence-free survival in early-onset breast cancer.
Methods and Findings
Suppression subtractive hybridization identified DEAR1 as a novel gene mapping to a region of high-frequency loss of heterozygosity (LOH) in a number of histologically diverse human cancers within Chromosome 1p35.1. In the breast epithelium, DEAR1 expression is limited to the ductal and glandular epithelium and is down-regulated in transition to ductal carcinoma in situ (DCIS), an early histologic stage in breast tumorigenesis. DEAR1 missense mutations and homozygous deletion (HD) were discovered in breast cancer cell lines and tumor samples. Introduction of the DEAR1 wild type and not the missense mutant alleles to complement a mutation in a breast cancer cell line, derived from a 36-year-old female with invasive breast cancer, initiated acinar morphogenesis in three-dimensional (3D) basement membrane culture and restored tissue architecture reminiscent of normal acinar structures in the mammary gland in vivo. Stable knockdown of DEAR1 in immortalized human mammary epithelial cells (HMECs) recapitulated the growth in 3D culture of breast cancer cell lines containing mutated DEAR1, in that shDEAR1 clones demonstrated disruption of tissue architecture, loss of apical basal polarity, diffuse apoptosis, and failure of lumen formation. Furthermore, immunohistochemical staining of a tissue microarray from a cohort of 123 young female breast cancer patients with a 20-year follow-up indicated that in early-onset breast cancer, DEAR1 expression serves as an independent predictor of local recurrence-free survival and correlates significantly with strong family history of breast cancer and the triple-negative phenotype (ER−, PR−, HER-2−) of breast cancers with poor prognosis.
Our data provide compelling evidence for the genetic alteration and loss of expression of DEAR1 in breast cancer, for the functional role of DEAR1 in the dominant regulation of acinar morphogenesis in 3D culture, and for the potential utility of an immunohistochemical assay for DEAR1 expression as an independent prognostic marker for stratification of early-onset disease.
Editors' Summary
Each year, more than one million women discover that they have breast cancer. This type of cancer begins when cells in the breast that line the milk-producing glands or the tubes that take the milk to the nipples (glandular and ductal epithelial cells, respectively) acquire genetic changes that allow them to grow uncontrollably and to move around the body (metastasize). The uncontrolled division leads to the formation of a lump that can be detected by mammography (a breast X-ray) or by manual breast examination. Breast cancer is treated by surgical removal of the lump or, if the cancer has started to spread, by removal of the whole breast (mastectomy). Surgery is usually followed by radiotherapy or chemotherapy. These “adjuvant” therapies are designed to kill any remaining cancer cells but can make patients very ill. Generally speaking, the outlook for women with breast cancer is good. In the US, for example, nearly 90% of affected women are still alive five years after their diagnosis.
Why Was This Study Done?
Although breast cancer is usually diagnosed in women in their 50s or 60s, some women develop breast cancer much earlier. In these women, the disease is often very aggressive. Compared to older women, young women with breast cancer have a lower overall survival rate and their cancer is more likely to recur locally or to metastasize. It would be useful to be able to recognize those younger women at the greatest risk of cancer recurrence so that they could be offered intensive surveillance and adjuvant therapy; those women at a lower risk could have gentler treatments. To achieve this type of “stratification,” the genetic changes that underlie breast cancer in young women need to be identified. In this study, the researchers discover a gene that is genetically altered (by mutations or deletion) in early-onset breast cancer and then investigate whether its expression can predict outcomes in women with this disease.
What Did the Researchers Do and Find?
The researchers used “suppression subtractive hybridization” to identify a new gene in a region of human Chromosome 1 where loss of heterozygosity (LOH; a genetic alteration associated with cancer development) frequently occurs. They called the gene DEAR1 (ductal epithelium-associated RING Chromosome 1) to indicate that it is expressed in ductal and glandular epithelial cells and encodes a “RING finger” protein (specifically, a subtype called a TRIM protein; RING finger proteins such as BRCA1 and BRCA2 have been implicated in early cancer development and in a large fraction of inherited breast cancers). DEAR1 expression was reduced or lost in several ductal carcinomas in situ (a local abnormality that can develop into breast cancer) and advanced breast cancers, the researchers report. Furthermore, many breast tumors carried DEAR1 missense mutations (genetic changes that interfere with the normal function of the DEAR1 protein) or had lost both copies of DEAR1 (the human genome contains two copies of most genes). To determine the function of DEAR1, the researchers replaced a normal copy of DEAR1 into a breast cancer cell that had a mutation in DEAR1. They then examined the growth of these genetically manipulated cells in special three-dimensional cultures. The breast cancer cells without DEAR1 grew rapidly without an organized structure while the breast cancer cells containing the introduced copy of DEAR1 formed structures that resembled normal breast acini (sac-like structures that secrete milk). In normal human mammary epithelial cells, the researchers silenced DEAR1 expression and also showed that without DEAR1, the normal mammary cells lost their ability to form proper acini. Finally, the researchers report that DEAR1 expression (detected “immunohistochemically”) was frequently lost in women who had had early-onset breast cancer and that the loss of DEAR1 expression correlated with reduced local recurrence-free survival, a strong family history of breast cancer and with a breast cancer subtype that has a poor outcome.
What Do These Findings Mean?
These findings indicate that genetic alteration and loss of expression of DEAR1 are common in breast cancer. Although laboratory experiments may not necessarily reflect what happens in people, the results from the three-dimensional culture of breast epithelial cells suggest that DEAR1 may regulate the normal acinar structure of the breast. Consequently, loss of DEAR1 expression could be an early event in breast cancer development. Most importantly, the correlation between DEAR1 expression and both local recurrence in early-onset breast cancer and a breast cancer subtype with a poor outcome suggests that it might be possible to use DEAR1 expression to identify women with early-onset breast cancer who have an increased risk of local recurrence so that they get the most appropriate treatment for their cancer.
Additional Information
Please access these Web sites via the online version of this summary at
This study is further discussed in a PLoS Medicine Perspective by Senthil Muthuswamy
The US National Cancer Institute provides detailed information for patients and health professionals on all aspects of breast cancer, including information on genetic alterations in breast cancer (in English and Spanish)
The MedlinePlus Encyclopedia provides information for patients about breast cancer; MedlinePlus also provides links to many other breast cancer resources (in English and Spanish)
The UK charities Cancerbackup (now merged with MacMillan Cancer Support) and Cancer Research UK also provide detailed information about breast cancer
PMCID: PMC2673042  PMID: 19536326
10.  Association between mammographic density and basal-like and luminal A breast cancer subtypes 
Mammographic density is a strong risk factor for breast cancer overall, but few studies have examined the association between mammographic density and specific subtypes of breast cancer, especially aggressive basal-like breast cancers. Because basal-like breast cancers are less frequently screen-detected, it is important to understand how mammographic density relates to risk of basal-like breast cancer.
We estimated associations between mammographic density and breast cancer risk according to breast cancer subtype. Cases and controls were participants in the Carolina Breast Cancer Study (CBCS) who also had mammograms recorded in the Carolina Mammography Registry (CMR). A total of 491 cases had mammograms within five years prior to and one year after diagnosis and 528 controls had screening or diagnostic mammograms close to the dates of selection into CBCS. Mammographic density was reported to the CMR using Breast Imaging Reporting and Data System categories. The expression of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 1 and 2 (HER1 and HER2), and cytokeratin 5/6 (CK5/6) were assessed by immunohistochemistry and dichotomized as positive or negative, with ER+ and/or PR+, and HER2- tumors classified as luminal A and ER-, PR-, HER2-, HER1+ and/or CK5/6+ tumors classified as basal-like breast cancer. Triple negative tumors were defined as negative for ER, PR and HER2. Of the 491 cases 175 were missing information on subtypes; the remaining cases included 181 luminal A, 17 luminal B, 48 basal-like, 29 ER-/PR-/HER2+, and 41 unclassified subtypes. Odds ratios comparing each subtype to all controls and case-case odds ratios comparing mammographic density distributions in basal-like to luminal A breast cancers were estimated using logistic regression.
Mammographic density was associated with increased risk of both luminal A and basal-like breast cancers, although estimates were imprecise. The magnitude of the odds ratio associated with mammographic density was not substantially different between basal-like and luminal A cancers in case–control analyses and case-case analyses (case-case OR = 1.08 (95% confidence interval: 0.30, 3.84)).
These results suggest that risk estimates associated with mammographic density are not distinct for separate breast cancer subtypes (basal-like/triple negative vs. luminal A breast cancers). Studies with a larger number of basal-like breast cancers are needed to confirm our findings.
PMCID: PMC3978452  PMID: 24008056
Mammographic density; Breast cancer; Subtypes; Basal-like; Epidemiology
11.  PAM50 Breast Cancer Subtyping by RT-qPCR and Concordance with Standard Clinical Molecular Markers 
BMC Medical Genomics  2012;5:44.
Many methodologies have been used in research to identify the “intrinsic” subtypes of breast cancer commonly known as Luminal A, Luminal B, HER2-Enriched (HER2-E) and Basal-like. The PAM50 gene set is often used for gene expression-based subtyping; however, surrogate subtyping using panels of immunohistochemical (IHC) markers are still widely used clinically. Discrepancies between these methods may lead to different treatment decisions.
We used the PAM50 RT-qPCR assay to expression profile 814 tumors from the GEICAM/9906 phase III clinical trial that enrolled women with locally advanced primary invasive breast cancer. All samples were scored at a single site by IHC for estrogen receptor (ER), progesterone receptor (PR), and Her2/neu (HER2) protein expression. Equivocal HER2 cases were confirmed by chromogenic in situ hybridization (CISH). Single gene scores by IHC/CISH were compared with RT-qPCR continuous gene expression values and “intrinsic” subtype assignment by the PAM50. High, medium, and low expression for ESR1, PGR, ERBB2, and proliferation were selected using quartile cut-points from the continuous RT-qPCR data across the PAM50 subtype assignments.
ESR1, PGR, and ERBB2 gene expression had high agreement with established binary IHC cut-points (area under the curve (AUC) ≥ 0.9). Estrogen receptor positivity by IHC was strongly associated with Luminal (A and B) subtypes (92%), but only 75% of ER negative tumors were classified into the HER2-E and Basal-like subtypes. Luminal A tumors more frequently expressed PR than Luminal B (94% vs 74%) and Luminal A tumors were less likely to have high proliferation (11% vs 77%). Seventy-seven percent (30/39) of ER-/HER2+ tumors by IHC were classified as the HER2-E subtype. Triple negative tumors were mainly comprised of Basal-like (57%) and HER2-E (30%) subtypes. Single gene scoring for ESR1, PGR, and ERBB2 was more prognostic than the corresponding IHC markers as shown in a multivariate analysis.
The standard immunohistochemical panel for breast cancer (ER, PR, and HER2) does not adequately identify the PAM50 gene expression subtypes. Although there is high agreement between biomarker scoring by protein immunohistochemistry and gene expression, the gene expression determinations for ESR1 and ERBB2 status was more prognostic.
PMCID: PMC3487945  PMID: 23035882
12.  GATA3 expression in breast carcinoma: utility in triple-negative, sarcomatoid, and metastatic carcinomas☆, ☆☆ 
Human pathology  2013;44(7):1341-1349.
GATA3 plays an integral role in breast luminal cell differentiation and is implicated in breast cancer progression. GATA3 immunohistochemistry is a useful marker of breast cancer; however, its use in specific subtypes is unclear. Here, we evaluate GATA3 expression in 86 invasive ductal carcinomas including triple-negative, Her-2, and luminal subtypes, in addition to 13 metaplastic carcinomas and in 34 fibroepithelial neoplasms. In addition, we report GATA3 expression in matched primary and metastatic breast carcinomas in 30 patients with known estrogen receptor (ER), progesterone receptor (PR), and Her-2 status, including 5 with ER and/or PR loss from primary to metastasis. Tissue microarrays containing 5 to 10 cores per tumor were stained for GATA3, scored as follows: 0 (0–5%), 1+ (6%–25%), 2+ (26%–50%), 3+ (51%–75%), and 4+ (>75%). GATA3 labeling was seen in 67% (66/99) of primary ductal carcinomas including 43% of triple-negative and 54% of metaplastic carcinomas. In contrast, stromal GATA3 labeling was seen in only 1 fibroepithelial neoplasm. GATA3 labeling was seen in 90% (27/30) of primary breast carcinomas in the paired cohort, including 67% of triple-negative carcinomas. GATA3 labeling was overwhelmingly maintained in paired metastases. Notably, GATA3 was maintained in all “luminal loss” metastases, which showed ER and/or PR loss. In conclusion, GATA3 expression is maintained between matched primary and metastatic carcinomas including ER-negative cases. GATA3 can be particularly useful as a marker for metastatic breast carcinoma, especially triple-negative and metaplastic carcinomas, which lack specific markers of mammary origin. Finally, GATA3 labeling may help distinguish metaplastic carcinoma from malignant phyllodes tumors.
PMCID: PMC3991123  PMID: 23375642
GATA3; Breast carcinoma; Metastatic breast carcinoma; Metaplastic carcinoma
13.  Survival Analysis Based on Clinicopathological Data from a Single Institution: Chemotherapy Intensity Would Be Enhanced in Patients with Positive Hormone Receptors and Positive HER2 in China Who Cannot Afford the Target Therapy 
ISRN Oncology  2013;2013:606398.
Background. Immunohistochemical markers were often used to classify breast cancer into subtypes. The aim of this study was to estimate death and tumor progression for patients with the major subtypes of breast cancer as classified using immunohistochemical assay and to investigate the patterns of benefit from the therapies over the past years. Methods. The study population included primary, operable 199 invasive ductal breast cancer patients, with the median age of 51.1 years old. All patients underwent local and/or systemic treatments. The clinicopathological characteristics and clinical outcomes were retrospectively reviewed. The expression of estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2, and Ki67 was analyzed by immunohistochemistry. All patients were classified into the following categories: luminal A, luminal B, HER2 overexpression, and triple-negative subtypes. Result. The median follow-up time was 33 months. Luminal A tumors had the lowest rate of tumor progression (0%, P = 0.006), while luminal B, HER2 over-expression, and triple-negative subtypes were associated with an increased risk of tumor progression (15.4, 19.2, 15.4%). Clinicopathological subtypes retained independent prognostic significance (P = 0.008). There were significant differences by Cox model analyzed in age, menopause, lymph node metastasis, and HER2 for the event of death and tumor progression (P < 0.05), and there were significant differences only in chemotherapy for the event, respectively (P < 0.05). Conclusion. Clinicopathological subtypes of breast cancer could robustly identify the risk of death and tumor progression and were significant in making therapeutic decision. HER2 was the important poor indicator. The chemotherapy intensity would be enhanced for patients with luminal B, especially for HER2 over-expression subgroup.
PMCID: PMC3747482  PMID: 23984097
14.  Expression of matrix metalloproteinases and their inhibitors in different immunohistochemical-based molecular subtypes of breast cancer 
BMC Cancer  2014;14:959.
Metalloproteinases (MMPs) and their tissue inhibitors of metalloproteinases (TIMPs) are involved in several key pathways of tumor growth, invasion and metastasis, but little is known about their expression according to different molecular subtypes of breast cancer. The aims of this study were to assess the prevalence and clinical significance of MMP and TIMP expression in invasive breast cancer and to determine its association with immunohistochemical-based molecular classification.
Tissue microarray sections were immunostained for estrogen receptor-α (ER-α), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), cytokeratin (CK) 5/6, epidermal growth factor receptor (EGFR) and with specific antibodies against MMP-1, 2, 7, 9, 11, 13, and 14 and TIMP-1, 2, and 3. Based on the immunostaining data from five of the markers used (ER-α, PR, HER2, EGFR and CK5/6), three major subtypes (123 luminal A, 31 basal-like, and 17 HER2-overexpressing) were selected.
Statistically significant differences in the expression of MMPs and TIMPs among the three subtypes were found in tumoral MMP7 (P = 0.005), tumoral MMP-9 (P = 0.000), tumoral MMP-13 (P = 0.016) and stromal MMP-13 (P = 0.016). The incidence of tumoral MMP-9 expression in the HER2-overexpressing subtype was significantly higher than in the luminal A subtype (P = 0.021). Tumoral MMP-9 and stromal MMP-13 expression were significantly higher in the HER2-overexpressing subtype than in the basal-like subtype (P = 0.000 and P = 0.016, respectively). Tumoral MMP-7 expression was significantly higher in the basal-like subtype compared to luminal A (P = 0.007) and HER2-overexpressing subtype (P = 0.004). Tumoral MMP-13 showed a higher expression in the basal-like subtype than in the HER2-overexpressing subtype (P = 0.010). In multivariate analysis, stage and stromal MMP-1 expression were significantly related to overall survival. Stage was of independent prognostic significance for disease-free survival.
We found some variations in MMP and TIMP expression among the immunohistochemical-based molecular subtypes of breast carcinomas, suggesting differences in their tumor pathophysiology. Additional studies are needed to determine the mechanisms underlying the differences of MMP and TIMP expression in the molecular subtypes for the development of specific therapeutic targets for breast cancer subtypes.
PMCID: PMC4301952  PMID: 25510449
Breast cancer; Molecular subtype; Immunohistochemistry; Matrix metalloproteinase; Tissue inhibitor of metalloproteinase
15.  Phenotypic and molecular characterization of the claudin-low intrinsic subtype of breast cancer 
In breast cancer, gene expression analyses have defined five tumor subtypes (luminal A, luminal B, HER2-enriched, basal-like and claudin-low), each of which has unique biologic and prognostic features. Here, we comprehensively characterize the recently identified claudin-low tumor subtype.
The clinical, pathological and biological features of claudin-low tumors were compared to the other tumor subtypes using an updated human tumor database and multiple independent data sets. These main features of claudin-low tumors were also evaluated in a panel of breast cancer cell lines and genetically engineered mouse models.
Claudin-low tumors are characterized by the low to absent expression of luminal differentiation markers, high enrichment for epithelial-to-mesenchymal transition markers, immune response genes and cancer stem cell-like features. Clinically, the majority of claudin-low tumors are poor prognosis estrogen receptor (ER)-negative, progesterone receptor (PR)-negative, and epidermal growth factor receptor 2 (HER2)-negative (triple negative) invasive ductal carcinomas with a high frequency of metaplastic and medullary differentiation. They also have a response rate to standard preoperative chemotherapy that is intermediate between that of basal-like and luminal tumors. Interestingly, we show that a group of highly utilized breast cancer cell lines, and several genetically engineered mouse models, express the claudin-low phenotype. Finally, we confirm that a prognostically relevant differentiation hierarchy exists across all breast cancers in which the claudin-low subtype most closely resembles the mammary epithelial stem cell.
These results should help to improve our understanding of the biologic heterogeneity of breast cancer and provide tools for the further evaluation of the unique biology of claudin-low tumors and cell lines.
PMCID: PMC3096954  PMID: 20813035
16.  Geographic differences in the distribution of molecular subtypes of breast cancer in Brazil 
BMC Women's Health  2014;14:102.
To compare the distribution of the intrinsic molecular subtypes of breast cancer based on immunohistochemical profile in the five major geographic regions of Brazil, a country of continental dimension, with a wide racial variation of people.
The study was retrospective observational. We classified 5,687 invasive breast cancers by molecular subtype based on immunohistochemical expression of estrogen-receptor (ER), progesterone-receptor (PR), human epidermal growth factor receptor 2 (HER2), and Ki-67 proliferation index. Cases were classified as luminal A (ER and/or PR positive and HER2 negative, Ki-67 < 14%), luminal B (ER and/or PR positive, HER2 negative, and Ki-67 > 14%), triple-positive (ER and/or PR positive and HER2 positive), HER2-enriched (ER and PR negative, and HER2- positive), and triple-negative (TN) (ER negative, PR negative, and HER2- negative). Comparisons of the ages of patients and molecular subtypes between different geographic regions were performed.
South and Southeast regions with a higher percentage of European ancestry and higher socioeconomic status presented with the highest proportion of luminal tumors. The North region presented with more aggressive subtypes (HER2-enriched and triple-negative), while the Central-West region predominated triple-positive carcinomas. The Northeast—a region with a high African influence—presented intermediate frequency of the different molecular subtypes. The differences persisted in subgroups of patients under and over 50 years.
The geographic regions differ according to the distribution of molecular subtypes of breast cancer. However, other differences, beside those related to African ancestry, such as socioeconomic, climatic, nutritional, and geographic, have to be considered to explain our results. The knowledge of the differences in breast cancer characteristics among the geographic regions may help to organize healthcare programs in large countries like Brazil with diverse economic and race composition among different geographic regions.
PMCID: PMC4153008  PMID: 25174527
Breast cancer; Epidemiology; Brazilian races; Intrinsic molecular subtypes
17.  Triple-negative vimentin-positive heterogeneous feline mammary carcinomas as a potential comparative model for breast cancer 
BMC Veterinary Research  2014;10:185.
Human breast cancer is a heterogeneous disease classified by molecular subtyping into luminal A, luminal B, HER2-overexpressing, basal-like, claudin-low and normal-breast like. The routinely applied and standardized immunohistochemical-based surrogates of this classification group together the last three entities as triple-negative breast cancer (TNBCs) that show the most diverse and complex heterogeneity and represent a therapeutic challenge.
In the present work 156 feline mammary lesions consisting of feline mammary carcinomas (FMCs), benign neoplasms, and hyperplastic/dysplastic tissues were evaluated histologically and by immunohistochemistry for expression of basal and luminal cytokeratins (CK), vimentin, alpha-smooth muscle actin, calponin, estrogen receptor (ER) alpha (a), and progesterone receptor (PR). Thirty-seven FMCs with 27 matched non-neoplastic controls were also investigated for gene expression of ERa, ER beta, PR, and HER2.
A large group of hormone receptors (HRs)-negative aggressive carcinomas - that did not overexpress HER2 - could be distinguished from the less aggressive (10.8%) and benign (8%) HRs + tumors, that showed bilineage (luminal and myoepithelial) differentiation. Immunohistochemical evaluations of cytoplasmic filaments indicated that HRs- FMCs are vimentin+, CK14+, and CK5_6+ carcinomas that may resemble the TNBCs (basal like/claudin low) described in women. The identification of luminal and myoepithelial progenitors within the mammary ductal system suggested potential cells/sites of origin of these tumors. A diffuse and never previously described CKs/vimentin luminal cell co-expression was detected in the non-neoplastic ducts, indicating a potential bilineage progenitor.
These results indicate and potentially explain the high incidence of triple-negative, vimentin + aggressive tumors in cats that may used to elucidate some of the challenging features of TNBCs in women.
PMCID: PMC4180584  PMID: 25249140
Mammary tumor; Feline; Human breast cancer; Vimentin; Markers; Triple-negative
18.  Distinct choline metabolic profiles are associated with differences in gene expression for basal-like and luminal-like breast cancer xenograft models 
BMC Cancer  2010;10:433.
Increased concentrations of choline-containing compounds are frequently observed in breast carcinomas, and may serve as biomarkers for both diagnostic and treatment monitoring purposes. However, underlying mechanisms for the abnormal choline metabolism are poorly understood.
The concentrations of choline-derived metabolites were determined in xenografted primary human breast carcinomas, representing basal-like and luminal-like subtypes. Quantification of metabolites in fresh frozen tissue was performed using high-resolution magic angle spinning magnetic resonance spectroscopy (HR MAS MRS).
The expression of genes involved in phosphatidylcholine (PtdCho) metabolism was retrieved from whole genome expression microarray analyses.
The metabolite profiles from xenografts were compared with profiles from human breast cancer, sampled from patients with estrogen/progesterone receptor positive (ER+/PgR+) or triple negative (ER-/PgR-/HER2-) breast cancer.
In basal-like xenografts, glycerophosphocholine (GPC) concentrations were higher than phosphocholine (PCho) concentrations, whereas this pattern was reversed in luminal-like xenografts. These differences may be explained by lower choline kinase (CHKA, CHKB) expression as well as higher PtdCho degradation mediated by higher expression of phospholipase A2 group 4A (PLA2G4A) and phospholipase B1 (PLB1) in the basal-like model. The glycine concentration was higher in the basal-like model. Although glycine could be derived from energy metabolism pathways, the gene expression data suggested a metabolic shift from PtdCho synthesis to glycine formation in basal-like xenografts. In agreement with results from the xenograft models, tissue samples from triple negative breast carcinomas had higher GPC/PCho ratio than samples from ER+/PgR+ carcinomas, suggesting that the choline metabolism in the experimental models is representative for luminal-like and basal-like human breast cancer.
The differences in choline metabolite concentrations corresponded well with differences in gene expression, demonstrating distinct metabolic profiles in the xenograft models representing basal-like and luminal-like breast cancer. The same characteristics of choline metabolite profiles were also observed in patient material from ER+/PgR+ and triple-negative breast cancer, suggesting that the xenografts are relevant model systems for studies of choline metabolism in luminal-like and basal-like breast cancer.
PMCID: PMC2931488  PMID: 20716336
19.  Use of Four Biomarkers to Evaluate the Risk of Breast Cancer Subtypes in the Women’s Contraceptive and Reproductive Experiences Study 
Cancer research  2010;70(2):575-587.
Epidemiological studies have suggested that some hormone-related breast cancer risk factors differentially influence risk of breast cancer subtypes defined by estrogen receptor (ER) and progesterone receptor (PR) expression status in tumor tissue. However, it remains unclear whether human epidermal growth factor receptor-2 (HER2) and p53 protein (p53) expression status in tumor tissue further differentiate these exposure-risk-group associations. We evaluated the associations of oral contraceptive (OC) use and reproductive factors with incident invasive breast cancer subtypes among 1197 population-based cases and 2015 controls from the Los Angeles County or Detroit components of the Women’s Contraceptive and Reproductive Experiences Study. We used multivariable polychotomous unconditional logistic regression methods to conduct case-control comparisons by ER/PR/HER2/p53 status. We found that OC use was not associated with any breast cancer subtype defined by ER/PR/HER2/p53, except for a 2.9-fold increased risk for triple negative (ER−/PR−/HER2−) tumors among older women (ages 45–64 years) who started OC use before age 18. Parity was associated with decreased risk of luminal A (ER+ or PR+, HER2−), luminal B (ER+ or PR+, HER2+), and ER−/PR−/HER2+ tumors. Age at first full-term pregnancy was positively associated with luminal A tumors among older women. Neither of these reproductive factors was associated with triple negative tumors. Long duration of breastfeeding lowered risk of triple negative and luminal A tumors. No further differential risk patterns were noted when p53 was also considered. These results provide evidence supporting a difference in some hormone-related risk factor profiles between triple negative and other breast cancer subtypes defined by ER/PR/HER2.
PMCID: PMC2807992  PMID: 20068186
ER/PR/HER2/p53; breast cancer; hormone-related factors; oral contraceptive; reproductive factors
20.  Carcinosarcoma of the breast: two case reports and review of the literature 
Cases Journal  2009;2:15.
Carcinosarcoma of the breast, often referred to as metaplastic carcinoma of the breast, is a rare malignancy with two distinct cell lines described as a breast carcinoma of ductal type with a sarcoma-like component. Clinically, carcinosarcoma of the breast is an aggressive breast cancer. The prognosis for carcinosarcoma of the breast is less favorable compared to more common types of breast cancer such as infiltrating ductal or lobular carcinoma. Currently, the evaluation of breast carcinoma includes hormone receptor analysis of the tumor tissue, with those positive for estrogen or progesterone responding better to both hormonal and chemotherapy.
Trastuzumab (Herceptin®) is available as an adjunct treatment for tumors which over-express the HER2/neu gene. Typically, metaplastic carcinomas of the breast do not express the estrogen or progesterone receptors and do not over-express the HER2/neu oncogene. As a result of this "triple negative" phenotype, such tumors tend to be more aggressive and are unlikely to respond to targeted therapy with Herceptin. The epidermal growth factor receptor HER-1/EGFR protein is expressed in the majority of metaplastic carcinomas and thus may serve as a potential therapeutic target for EGFR inhibitors such as gefitinib and cetuximab. The two cases we describe exemplify the aggressive nature of carcinosarcoma of the breast and support the findings that this tumor type does not express the common receptors found in other breast carcinomas. These case reports also emphasize the need for investigating the role for blockade of the HER-1/EGFR receptor with targeted therapies when found to be over-expressed in the primary tumor.
PMCID: PMC2627815  PMID: 19126225
21.  Expression of Immunohistochemical Markers before and after Neoadjuvant Chemotherapy in Breast Carcinoma, and Their Use as Predictors of Response 
Journal of Breast Cancer  2013;16(4):395-403.
For patients with breast carcinoma, immunohistochemical markers are important factors in determining the breast cancer subtype and for establishing a therapeutic plan, including the use of neoadjuvant chemotherapy (NACT). However, it is not clear whether the expression of certain markers changes after NACT.
We assessed estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), Ki-67, p53, and Bcl-2 expression in specimens from 345 breast cancer cases before and after NACT. We analyzed the association between response to NACT and the expression of the markers in pre-NACT specimens. We also compared the expression between pre- and post-NACT specimens.
ER and PR expression was negatively associated with pathological complete response (pCR). HER2 was associated with pCR in all cases, but the association was lost when the cases were subdivided according to hormone receptor status. The pre-NACT tumor size of cases with pCR after NACT was smaller than that of cases with residual disease. HER2-enriched and triple-negative breast cancers were more likely to achieve pCR than luminal A type cancers. PR expression and the Ki-67 index decreased after NACT. A decrease in the Ki-67 index was also demonstrated in hormone receptor positive and HER2-enriched subtypes, but no similar tendency was observed in the triple-negative subtype.
A patient with breast cancer scheduled for NACT should be assessed for the breast cancer subtype, as this will influence the treatment plans for the patient. The expression of PR and Ki-67 after NACT should be interpreted carefully because NACT tends to reduce the expression of these molecules.
PMCID: PMC3893341  PMID: 24454461
Breast neoplasms; Drug therapy; Immunohistochemistry; Ki-67 antigen; Progesterone receptors
22.  Androgen receptor (AR) expression in 400 breast carcinomas: is routine AR assessment justified? 
Background: Triple negative breast carcinomas (TNBC) do not benefit from hormonal or Herceptin therapies. In search of novel therapeutic targets for TNBC, interest is escalating in a subset of these tumors that are androgen receptor (AR) positive with potential benefit from anti-androgen therapy. Against this background, the frequency of AR expression alone and in combination with other markers and morphologic features was assessed to identify TNBC subtypes for targeted therapy. Methods: 400 consecutive invasive mammary carcinomas with known estrogen receptor (ER), progesterone receptor (PR), androgen receptor (AR) and HER2 status were selected for study. The frequency of AR positivity alone or in combination with other markers was recorded with specific attention to the morphology of AR+ TNBCs. Ki67 was evaluated in selected group of cases. ASCO/CAP guidelines were used for interpretation of the various biomarkers. Results: Of the 400 tumors, 32 (8%) carcinomas were quadruple negative (ER-, PR-, AR-, Her2-), while 50 tumors (12.5%) were triple negative (ER-, PR-, Her2-); 18 (36%) of the triple negative tumors were AR positive and 10 (55%) of these were classic apocrine carcinomas. Fourteen cases, all apocrine carcinomas, were AR and Her2 positive. All 32 QN carcinomas were poorly differentiated and they had the highest Ki67 labeling index. Conclusion: The relatively high proportion of AR+ tumors (36%) among the 50 triple negative carcinomas is an important finding in support of routine assessment of AR in at least all TNBCs and apocrine carcinomas as a potential target for therapy.
PMCID: PMC4106653  PMID: 25057438
Androgen receptor (AR); estrogen receptor (ER); progesterone receptor (PR); HER2; breast cancer
23.  Breast Cancer Subtype as a Predictor of Lymph Node Metastasis according to the SEER Registry 
Journal of Breast Cancer  2015;18(2):143-148.
Breast cancer subtype correlates with response to systemic therapy and overall survival (OS), but its impact on lymphatic spread is incompletely understood. In this study, we used the Surveillance, Epidemiology, and End Results registry to assess whether the subtype can predict the presence of nodal metastasis or advanced nodal stage in breast cancer.
A total of 7,274 eligible patients diagnosed with T1-3 infiltrating ductal carcinoma with known estrogen or progesterone hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) status, who underwent surgical excision of the primary tumor and pathologic lymph node evaluation, were included in this analysis. Patients were categorized into four breast cancer subtypes: HR+/HER2-; HR+/HER2+; HR-/HER2+; and HR-/HER2-. Binary logistic regression analysis was used to determine whether breast cancer subtype, tumor size, tumor grade, patient race, and patient age at diagnosis are independently predictive of lymph node positivity or advanced nodal stage. The Pearson chi-square test was used to determine whether progesterone receptor (PR) status had an impact on the incidence of lymph node positivity in estrogen receptor (ER) positive patients.
Independent predictors of nodal positivity included breast cancer subtype (p=0.040), tumor size (p<0.001), tumor grade (p<0.001), and patient age (p<0.001), whereas only tumor size (p<0.001), grade (p=0.001), and patient age (p=0.005) predicted advanced nodal stage. Triple-negative cancers had a significantly lower risk of nodal positivity than the HR+/HER2- subtype (odds ratio, 0.686; p=0.004), but no other significant differences between subtypes were observed. There was also no difference in lymph node positivity between PR+ and PR- tumors amongst ER+/HER2- (p=0.228) or ER+/HER2+ tumors (p=0.713).
The HR+/HER2-breast cancer subtype has a higher rate of lymph node involvement at diagnosis than the triple-negative subtype. These findings may play a role in guiding regional management considerations if confirmed in further studies.
PMCID: PMC4490263  PMID: 26155290
Biological tumor markers; Breast neoplasms; Estrogen receptors
24.  Altered expression of estrogen receptor-α variant messenger RNAs between adjacent normal breast and breast tumor tissues 
Breast Cancer Research  1999;2(1):64-72.
Using semiquantitative reverse transcription-polymerase chain reaction assays, we investigated the expression of variant messenger RNAs relative to wild-type estrogen receptor (ER)-α messenger RNA in normal breast tissues and their adjacent matched breast tumor tissues. Higher ER variant truncated after sequences encoding exon 2 of the wild-type ER-α (ERC4) messenger RNA and a lower exon 3 deleted ER-α variant (ERD3) messenger RNA relative expression in the tumor compartment were observed in the ER-positive/PR-positive and the ER-positive subsets, respectively. A significantly higher relative expression of exon 5 deleted ER-α varient (ERD5) messenger RNA was observed in tumor components overall. These data demonstrate that changes in the relative expression of ER-α variant messenger RNAs occur between adjacent normal and neoplastic breast tissues. We suggest that these changes might be involved in the mechanisms that underlie breast tumorigenesis.
Estrogen receptor (ER)-α and ER-β are believed to mediate the action of estradiol in target tissues. Several ER-α and ER-β variant messenger RNAs have been identified in both normal and neoplastic human tissues. Most of these variants contain a deletion of one or more exons of the wild-type (WT) ER messenger RNAs. The putative proteins that are encoded by these variant messenger RNAs would therefore be missing some functional domains of the WT receptors, and might interfere with WT-ER signaling pathways. The detection of ER-α variants in both normal and neoplastic human breast tissues raised the question of their possible role in breast tumorigenesis.
We have previously reported an increased relative expression of exon 5 deleted ER-α variant (ERD5) messenger RNA and of another ER-α variant truncated of all sequences following the exon 2 of the WT ER-α (ERC4) messenger RNA in breast tumor samples versus independent normal breast tissues. In contrast, a decreased relative expression of exon 3 deleted ER-α variant (ERD3) messenger RNA in tumor tissues and cancer cell lines versus independent normal reduction mammoplasty samples has recently been reported. These data were obtained in tissues from different individuals and possible interindividual differences cannot be excluded.
The goal of this study was to investigate the expressions of ERC4, ERD5 and ERD3 variant messenger RNAs in normal breast tissues and their matched adjacent primary breast tumor tissues.
Materials and methods:
Eighteen cases were selected from the Manitoba Breast Tumor Bank, which had well separated and histopathologically characterized normal and adjacent neoplastic components. All tumors were classified as primary invasive ductal carcinomas. Six tumors were ER-negative/progesterone receptor (PR)-negative, nine were ER-positive/PR-positive, two were ER-positive/PR-negative, and one was ER-negative/PR-positive, as measured by ligand-binding assay. For each specimen, total RNA was extracted from frozen normal and tumor tissue sections and was reverse transcribed. The expressions of ERC4, ERD3 and ERD5 messenger RNAs relative to WT ER-α messenger RNA were investigated by previously validated semiquantitative reverse transcription polymerase chain reaction (PCR) assays performed using three different sets of primers.
As shown Figure 1a, two PCR products were obtained that corresponded to WT ER and ERC4 messenger RNAs. For each case, the mean of the ratios obtained in at least three independent PCR experiments is shown for both normal and tumor compartments (Fig 1b). A statistically higher ERC4 messenger RNA relative expression was found in the neoplastic components of ER-positive/PR-positive tumors, as compared with matched adjacent normal tissues (n = 9; P = 0.019, Wilcoxon signed-rank test).
Two PCR products were obtained that corresponded to WT ER and ERD3 messenger RNAs (Fig 2a). A significantly higher expression of ERD3 messenger RNA was observed in the normal compared with the adjacent neoplastic components of ER-positive subset (n =8; P =0.023, Wilcoxon signed-rank test; Fig 2b).
Two PCR products were obtained that corresponded to WT ER and ERD5 complementary DNAs (Fig 3a). As shown in Figure 3b, a statistically significant higher relative expression of ERD5 messenger RNA was observed in tumor components when this expression was measurable in both normal and adjacent tumor tissues (n =15; P =0.035, Wilcoxon signed-rank test).
A statistically significant higher ERC4 messenger RNA expression was found in ER-positive/PR-positive tumors as compared with matched normal breast tissues. ERC4 variant messenger RNA has previously been demonstrated to be more highly expressed in ER-positive tumors that showed poor as opposed to tumors that showed good prognostic characteristics. Interestingly, we also have reported similar levels of expression of ERC4 messenger RNA in primary breast tumors and their concurrent axillary lymph node metastases. Taken together, these data suggest that the putative role of the ERC4 variant might be important at different phases of breast tumorigenesis and tumor progression; alteration of ERC4 messenger RNA expression and resulting modifications in ER signaling pathway probably occur before breast cancer cells acquire the ability to metastasize. Transient expression assays revealed that the protein encoded by ERC4 messenger RNA was unable to activate the transcription of an estrogen-responsive element-reporter gene or to modulate the wild-type ER protein activity. The biologic significance of the changes observed in ERC4 messenger RNA expression during breast tumorigenesis remains to be determined.
A higher relative expression of ERD3 messenger RNA in the normal breast tissue components compared with adjacent neoplastic tissue was found in the ER-positive subgroup. These data are in agreement with the recently published report of Erenburg et al, who showed a decreased relative expression of ERD3 messenger RNA in neoplastic breast tissues compared with independent reduction mammoplasty and breast tumor. Transfection experiments showed that the activation of the transcription of the pS2 gene by estrogen was drastically reduced in the presence of increased ERD3 expression. The authors hypothesized that the reduction in ERD3 expression could be a prerequisite for breast carcinogenesis to proceed.
We observed a significantly higher relative expression of ERD5 messenger RNA in breast tumor components compared with matched adjacent normal breast tissue. These data confirm our previous observations performed on unmatched normal and neoplastic human breast tissues. Upregulated expression of this variant has already been reported in ER-negative/PR-positive tumors, as compared with ER-positive/PR-positive tumors, suggesting a possible correlation between ERD5 messenger RNA expression and breast tumor progression. Even though it has been suggested that ERD5 could be related to the acquisition of insensitivity to antiestrogen treatment (ie tamoxifen), accumulating data refute a general role for ERD5 in hormone-resistant tumors. Only ER-positive pS2-positive tamoxifen-resistant tumors have been shown to express significantly higher levels of ERD5 messenger RNA, as compared with control tumors. Taken together, these data suggest that the exact biologic significance of ERD5 variant expression during breast tumorigenesis and breast cancer progression, if any, remains unclear.
In conclusion, we have shown that the relative expressions of ERC4 and ERD5 variant messenger RNAs were increased in human breast tumor tissue, as compared with normal adjacent tissue, whereas the expression of ERD3 variant messenger RNA was decreased in breast tumor tissues. These results suggest that the expressions of several ER-α variant messenger RNAs are deregulated during human breast tumorigenesis. Further studies are needed to determine whether these changes are transposed at the protein level. Furthermore, the putative role of ER-α variants in the mechanisms that underlie breast tumorigenesis remains to be determined.
PMCID: PMC13912  PMID: 11400682
breast cancer; estrogen receptor; tumorigenesis; variant messenger RNA
25.  Gross cystic disease fluid protein 15 (GCDFP-15) expression in breast cancer subtypes 
BMC Cancer  2014;14:546.
Gross cystic disease fluid protein 15 (GCDFP-15), which is regulated by the androgen receptor (AR), is a diagnostic marker for mammary differentiation in histopathology. We determined the expression of GCDFP-15 in breast cancer subtypes, its potential prognostic and predictive value, as well as its relationship to AR expression.
602 pre-therapeutic breast cancer core biopsies from the phase III randomized neoadjuvant GeparTrio trial (NCT00544765) were investigated for GCDFP-15 expression by immunohistochemistry. Expression data were correlated with disease-free (DFS) and overall survival (OS) time as well as pathological complete response (pCR) to neoadjuvant chemotherapy.
239 tumors (39.7%) were GCDFP-15 positive. GCDFP-15 expression was positively linked to hormone receptor (HR) and HER2 positive tumor type, while most triple negative carcinomas were negative (p < 0.0001). GCDFP-15 was also strongly correlated to AR expression (p 0.001), and to the so-called molecular apocrine subtype (HR-/AR+, p < 0.0001). Higher rates of GCDFP-15 positivity were seen in tumors of lower grade (<0.0001) and negative nodal status (p = 0.008). GCDFP-15 positive tumors tended to have a more favourable prognosis than GCDFP-15 negative tumors (DFS (p = 0.052) and OS (p = 0.044)), which was not independent from other factors in multivariate analysis. GCDFP-15 expression was not linked to pCR. Histological apocrine differentiation was frequent in molecular apocrine carcinomas (60.7%), and was associated with GCDFP-15 within this group (p = 0.039).
GCDFP-15 expression is higher in tumors with favorable prognostic features. GCDFP-15 expression is further a frequent feature of AR positive tumors and the molecular apocrine subtype. It might have reduced sensitivity as a diagnostic marker for mammary differentiation in triple negative tumors as compared to HR or HER2 positive tumor types.
Electronic supplementary material
The online version of this article (doi:10.1186/1471-2407-14-546) contains supplementary material, which is available to authorized users.
PMCID: PMC4122770  PMID: 25070172
GCDFP-15; Breast cancer; Neoadjuvant chemotherapy; Apocrine; CUP

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