Lynch Syndrome, also known as hereditary non-polyposis colorectal cancer (HNPCC), is the most common form of inherited colorectal cancer, however, its identification still presents a challenge for health care providers. Clinically-based guidelines have been used as the basis for Lynch Syndrome screening in colorectal cancer patient populations. More recently, it has been argued that universal molecular testing strategies should be implemented to increase the selection of patients who should get germline testing for Lynch Syndrome. In this issue of AJG, Julie et al compare the performance of clinical guidelines with a molecular strategy based on universal microsatellite instability (MSI) testing for identifying patients with Lynch Syndrome from among 214 unselected, newly diagnosed CRC patients. The study highlights the need for a systematic approach to identify patients with Lynch Syndrome so that they and their relatives can be targeted for appropriate clinical management.
Individuals with Lynch syndrome, sometimes referred to as hereditary non-polyposis colorectal cancer (HNPCC), have an increased risk of developing colorectal cancer (CRC) as well as other cancers. The increased risk is due to inherited mutations in mismatch repair (MMR) genes, which reduce the ability of cells to repair DNA damage. Screening for Lynch syndrome in individuals newly diagnosed with colorectal cancer has been proposed as part of a strategy that combines tests and interventions to reduce the risk of colorectal cancer in the relatives of the colorectal cancer patients with Lynch Syndrome.
Lynch syndrome is the most common cause of inherited colorectal and endometrial cancers yet it is under-recognized in clinical practice. The relative merits of screening for Lynch syndrome among healthy adults without cancer versus among adults with colorectal or endometrial cancer are discussed in this Perspectives article. Newly diagnosed colorectal cancer patients are a much easier target population for screening and leads to more informative genetic test results, at a lower cost in most cases.
Lynch syndrome; population screening; genetic testing; mismatch repair genes
Germline mutations in the DNA mismatch repair genes predispose to Lynch syndrome, thus conferring a high relative risk of colorectal and endometrial cancer. The MLH1, MSH2 and MSH6 mutational spectrum reported so far involves minor alterations scattered throughout their coding regions as well as large genomic rearrangements. Therefore, a combination of complete sequencing and a specialized technique for the detection of genomic rearrangements should be conducted during a proper DNA-testing procedure. Our main goal was to successfully identify Lynch syndrome families and determine the spectrum of MLH1, MSH2 and MSH6 mutations in Greek Lynch families in order to develop an efficient screening protocol for the Greek colorectal cancer patients' cohort.
Forty-two samples from twenty-four families, out of which twenty two of Greek, one of Cypriot and one of Serbian origin, were screened for the presence of germline mutations in the major mismatch repair genes through direct sequencing and MLPA. Families were selected upon Amsterdam criteria or revised Bethesda guidelines.
Ten deleterious alterations were detected in twelve out of the twenty-four families subjected to genetic testing, thus our detection rate is 50%. Four of the pathogenic point mutations, namely two nonsense, one missense and one splice site change, are novel, whereas the detected genomic deletion encompassing exon 6 of the MLH1 gene has been described repeatedly in the LOVD database. The average age of onset for the development of both colorectal and endometrial cancer among mutation positive families is 43.2 years.
The mutational spectrum of the MMR genes investigated as it has been shaped by our analysis is quite heterogeneous without any strong indication for the presence of a founder effect.
Lynch syndrome (LS), or hereditary nonpolyposis colorectal cancer, is the most common hereditary colorectal cancer (CRC) syndrome, accounting for approximately 2–5% of all newly diagnosed cases of CRC. Patients with LS have an increased lifetime risk of colorectal (52.2% in women and 68.7% in men) and endometrial cancer (15–70%), as well as certain extra-colonic cancers. Germline mutations in one of several DNA mismatch repair genes underlie LS. Molecular testing has emerged as an indispensable strategy for the diagnosis of LS. The diagnostic work-up of at-risk individuals includes a careful family history evaluation, microsatellite instability, immunohistochemistry and germline DNA analysis. A positive test result can guide clinicians in formulating the appropriate screening, surveillance and management strategies. However, because of the absence of an overt phenotype, such as a diffuse polyposis, it is not always straightforward to recognize LS clinically.
genetic testing; immunohistochemistry; Lynch syndrome; microsatellite instability; mismatch repair genes
Summary of Recommendations
The Evaluation of Genomic Applications in Practice and Prevention (EGAPP) Working Group found sufficient evidence to recommend offering genetic testing for Lynch syndrome to individuals with newly diagnosed colorectal cancer to reduce morbidity and mortality in relatives. We found insufficient evidence to recommend a specific genetic testing strategy among the several examined.
Genetic testing to detect Lynch syndrome in individuals with newly diagnosed colorectal cancer (CRC) is proposed as a strategy to reduce CRC morbidity and mortality in their relatives (see Clinical Considerations section for definition of Lynch syndrome). The EGAPP Working Group (EWG) constructed a chain of evidence that linked genetic testing for Lynch syndrome in patients with newly diagnosed CRC with improved health outcomes in their relatives. We found that assessing patients who have newly diagnosed CRC with a series of genetic tests could lead to the identification of Lynch syndrome. Relatives of patients with Lynch syndrome could then be offered genetic testing, and, where indicated, colorectal, and possibly endometrial, cancer surveillance, with the expectation of improved health outcome. The EWG concluded that there is moderate certainty that such a testing strategy would provide moderate population benefit.
The EWG found adequate evidence to conclude that the analytic sensitivity and specificity for preliminary and diagnostic tests were high.
After accounting for the specific technologies and numbers of markers used, the EWG found at least adequate evidence to describe the clinical sensitivity and specificity for three preliminary tests, and for four selected testing strategies. These measures of clinical validity varied with each test and each strategy (see Clinical Considerations section).
The EWG found adequate evidence for testing uptake rates, adherence to recommended surveillance activities, number of relatives approachable, harms associated with additional follow-up, and effectiveness of routine colonoscopy. This chain of evidence supported the use of genetic testing strategies to reduce morbidity/mortality in relatives with Lynch syndrome. Several genetic testing strategies were potentially effective, but none was clearly superior. The evidence for or against effectiveness of identifying mismatch repair (MMR) gene mutations in reducing endometrial cancer morbidity or mortality was inadequate.
CRC is a common disease responsible for an estimated 52,000 deaths in the United States in 2007. In about 3% of newly diagnosed CRC, the underlying cause is a mutation in a MMR gene (Lynch syndrome) that can be reliably identified with existing laboratory tests. Relatives inheriting the mutation have a high (about 45% by age 70) risk of developing CRC. Evidence suggests these relatives will often accept testing and increased surveillance.
colorectal cancer; Lynch syndrome; HNPCC
Lynch syndrome is a heritable, cancer susceptibility syndrome. This study aims to review current and emerging trends in the identification of Lynch syndrome in the endometrial cancer patient population.
We performed a comprehensive review of past and present screening algorithms for Lynch syndrome, including a review of the utility of both the Amsterdam criteria and Bethesda guidelines. Because non-colon cancers have historically not been the focus of Lynch syndrome research, current literature is ripe with questions regarding screening among this patient population. Low BMI, age less than 50, positive family history and pathologic features have all been identified as risk factors in endometrial cancer patients who might benefit from Lynch screening. Additionally, based on experience at our own institution we offer a feasible screening algorithm for these patients.
A comprehensive review of the data demonstrated that immunohistochemistry is becoming an efficient, inexpensive way to screen tumors at risk for mismatch repair deficiency. The sensitivity and specificity of immunohistochemistry for predicting Lynch syndrome approaches 100%. Ideally, prospective screening of all endometrial cancer patients with IHC is a feasible, cost-efficient way to detect Lynch in this patient population given the limitations of using personal/family history of malignancy as well as pathologic risk factors.
It is imperative that clinicians be mindful of the risk of Lynch syndrome in women with endometrial cancer. Given the opportunity for colon cancer screening and prevention strategies to be initiated, the identification of probands with endometrial cancer as a result of Lynch syndrome will lead to a reduction in morbidity and mortality for these patients and their families.
Lynch syndrome; Endometrial cancer; Screening
Identifying families at high risk for the Lynch syndrome (ie, hereditary non-polyposis colorectal cancer) is critical for both genetic counseling and cancer prevention. Current clinical guidelines are effective but limited by applicability and cost.
To develop and validate a genetic counseling and risk prediction tool that estimates the probability of carrying a deleterious mutation in mismatch repair genes MLH1, MSH2, or MSH6 and the probability of developing colorectal or endometrial cancer.
Design, Setting, and Patients
External validation of the MMRpro model was conducted on 279 individuals from 226 clinic-based families in the United States, Canada, and Australia (referred between 1993–2005) by comparing model predictions with results of highly sensitive germline mutation detection techniques. MMRpro models the autosomal dominant inheritance of mismatch repair mutations, with parameters based on meta-analyses of the penetrance and prevalence of mutations and of the predictive values of tumor characteristics. The model’s prediction is tailored to each individual’s detailed family history information on colorectal and endometrial cancer and to tumor characteristics including microsatellite instability.
Main Outcome Measure
Ability of MMRpro to correctly predict mutation carrier status, as measured by operating characteristics, calibration, and overall accuracy.
In the independent validation, MMRpro provided a concordance index of 0.83 (95% confidence interval, 0.78–0.88) and a ratio of observed to predicted cases of 0.94 (95% confidence interval, 0.84–1.05). This results in higher accuracy than existing alternatives and current clinical guidelines.
MMRpro is a broadly applicable, accurate prediction model that can contribute to current screening and genetic counseling practices in a high-risk population. It is more sensitive and more specific than existing clinical guidelines for identifying individuals who may benefit from MMR germline testing. It is applicable to individuals for whom tumor samples are not available and to individuals in whom germline testing finds no mutation.
Lynch syndrome is the most common familial colorectal cancer syndrome. It is linked to germline mutations in one of four DNA mismatch repair (MMR) genes. A comprehensive family history is one important way to identify at-risk individuals. The elucidation of the molecular genetics of this syndrome has made it possible to screen for the disorder with molecular tests. Microsatellite instability and/or immunohistochemistry followed by germline testing for mutations in MMR genes is now a standard approach for clinically suspected cases. Correctly recognizing Lynch syndrome is essential for the application of appropriate screening and surveillance measures. Close surveillance and risk-reducing operations can decrease cancer-related mortality. In addition, counseling is an important component of the management of any family with Lynch syndrome.
Lynch syndrome; Mismatch repair gene; Microsatellite instability; Immunohistochemistry; Hereditary nonpolyposis colon cancer; Colon cancer
Young-onset colorectal cancer is clinicopathologically different from older-onset colorectal cancer and tends to occur in patients with hereditary germline conditions such as Lynch syndrome and familial adenomatous polyposis.
We describe the case of a 44-year-old man with a paternal history of colon polyps, a personal 2-year history of hematochezia, and a diagnosis of rectal cancer. Further clinical evaluation of the patient at our institution determined the cancer to be stage IIIA. The patient underwent genetic counseling and testing, which indicated he was negative for the most common familial cancer syndromes. After treatment with neoadjuvant chemoradiotherapy, surgery, and adjuvant chemotherapy, the patient has done well. We review the hereditary cancer syndromes and genetic tests to consider for patients with early-onset colorectal cancer.
This case underscores the importance of following cancer-screening guidelines.
adenomatous polyposis coli; attenuated familial adenomatous polyposis; colorectal cancer; familial adenomatous polyposis; microsatellite instability; MYH-associated polyposis
High levels of microsatellite instability (MSI-high) are a cardinal feature of colorectal tumors from patients with Lynch Syndrome. Other key characteristics of Lynch Syndrome are that these patients experience fewer metastases and have enhanced survival when compared to patients diagnosed with microsatellite stable (MSS) colorectal cancer. Many of the characteristics associated with Lynch Syndrome including enhanced survival are also observed in patients with sporadic MSI-high colorectal cancer. In this review we will present the current state of knowledge regarding the mechanisms that are utilized by the host to control colorectal cancer in Lynch Syndrome and why these same mechanisms fail in MSS colorectal cancers.
Combined colon and endometrial cancer screening is a patient-centered approach that is feasible and acceptable and may improve adherence to Lynch syndrome screening recommendations.
Endometrial and colorectal cancers are the most common cancers in Lynch syndrome. Consensus guidelines recommend annual endometrial biopsy (EMB) and regular colonoscopies. We assessed the feasibility of concurrently performing EMB and colonoscopy and evaluated women's perception of pain, satisfaction, and acceptability.
From July 2002 to December 2009, women who had a gene mutation for Lynch syndrome, met the Amsterdam II criteria, or had a high-risk situation that required screening were prospectively enrolled. After conscious sedation, the procedures were sequentially performed. Patients completed pre- and postprocedure questionnaires assessing pain, level of satisfaction, and acceptability. The Wilcoxon rank test and Mann-Whitney test were used to compare pain scores.
Forty-two women completed the study. Median age was 37 years (range, 25 to 73). Nineteen had previously had an EMB in the office setting. Women reported significantly lower median levels of pain in the combined procedure compared with previous office setting biopsies (P < .001). Regardless of parity, women reported significantly less pain for an EMB as part of the combined screen compared with an office EMB (parous, P = .003; nulliparous, P = .026). Women also reported a high level of satisfaction and more convenience in the combined procedure. All participants preferred combined to separately scheduled procedures and would recommend the combined procedure to their relatives.
Combined colon and endometrial cancer screening is a patient-centered approach that is feasible, acceptable, and may improve adherence to Lynch syndrome screening recommendations.
Physicians’ cancer-related family history assessment for Lynch syndrome is often inadequate. Furthermore, the extent to which clinicians recognize non-family history-related clues for Lynch syndrome is unclear. We reviewed an integrated electronic health record (EHR) to determine diagnostic evaluation for Lynch syndrome in patients diagnosed with colorectal cancer (CRC).
We conducted a retrospective cohort study of consecutive patients with CRC, newly diagnosed at a tertiary care VA facility, between 1999 and 2007. A detailed review of the EHR was conducted to evaluate the presence of family-history and non-family history-related criteria of the Bethesda guidelines. Patient outcomes (identification in clinical practice and referral for genetic testing) were also determined.
We identified a total of 499 patients (mean age=65.4 years, 98.6% male, 51.1% non-Hispanic white). At least 1 of the Bethesda criterion was met for 57 patients (11.4%); none were met for 198 (39.7%); and there was uncertainty for 244 (48.9%) because of inadequate family history documentation and/or the patient was unsure about their family history. Forty-nine patients met criteria unrelated to family history. Only 4 of 57 patients (7%) that met the Bethesda guidelines had documentation of counseling. Among 244 patients with uncertainty, a suspicion for Lynch syndrome was documented in the EHR of 6 patients (2.5%); 3 received counseling.
Lynch syndrome is under-recognized, even when patients have clear criteria unrelated to family history. Multifaceted strategies focused on reducing providers’ cognitive errors and harnessing EHR capabilities to improve recognition of Lynch syndrome are needed.
Lynch syndrome; health outcomes; familial colorectal cancer; practice patterns; missed diagnosis; guideline non-adherence; genetic evaluation; delayed cancer diagnosis
The risk of endometrial cancer (EC) subsequent to a diagnosis of colorectal cancer in women with a germline mutation in a mismatch repair gene (Lynch syndrome or HNPCC) is unknown. We estimated the risk of EC following a diagnosis of CRC for women with Lynch syndrome.
A retrospective cohort study was performed on women diagnosed with CRC with a germline mutation in a mismatch repair gene (Lynch Syndrome cases), and women with microsatellite stable CRC who were not known to carry a germline mutation (non-Lynch cases), identified from the Colon Cancer Family Registry. The incidence of EC following CRC was estimated and compared for women with and without Lynch syndrome, using adjusted hazards ratios calculated for time at risk among each group.
One hundred and twelve women with Lynch syndrome and a previous diagnosis of CRC were compared with 908 women without Lynch and with a microsatellite stable CRC diagnosis. The estimated ten year cumulative risk of EC subsequent to CRC was 23.4% (95% CI: 15–36%) for Lynch syndrome women compared to 1.6% (95% CI: 0.7–3.8%) for non-Lynch women. After adjusting for ascertainment, age at diagnosis and diagnosis of other cancers, risk of subsequent diagnosis with EC was elevated 6-fold in women with Lynch syndrome compared to non-Lynch women (HR 6.2; 95% CI 2.2–17.3; p=0.001).
Approximately one quarter of women diagnosed with Lynch syndrome-associated CRC developed EC within 10 years. This supports the sentinel cancer concept and suggests that active and early management is important for these women.
A growing number of individuals are diagnosed with hereditary cancer. Though increased levels of anxiety and depression have been demonstrated around the time of genetic counselling, most individuals handle life at increased risk well. Data have, however, been collected on individual basis, which led us to focus on family perspectives of hereditary cancer.
Lynch syndrome represents a major type of hereditary colorectal and gynaecological cancer. We preformed open-ended interviews with 27 informants from 9 Lynch syndrome families. Inductive content analysis revealed three major themes: transition to a risk family, patterns of communication and influence on family relations and individual roles.
Family members described how learning about Lynch syndrome shifted focus from daily issues to concerns about cancer. Changes in communication related to difficulties in talking to children about heredity and informing new family members and distant relatives about an increased risk of cancer. Influence on relations was exemplified by family members taking on different roles, e.g. females often being responsible for coordinating information about heredity and providing support. Families in which members had experienced cancer at young age typically informed children soon after learning about heredity and at young age, whereas families with experience of cancer at higher age postponed information and thereby also genetic counselling.
Three major family perspectives are described in Lynch syndrome families; becoming a risk family, patterns of communication and influence on family relations. Since these issues are central, our findings suggests that such family perspectives should be considered during genetic counselling in order to contribute to information spread, help family members cope with the increased risk, and motivate family members at risk to undergo surveillance.
Family; Relations; Communication; Lynch syndrome; Qualitative analysis
To determine the prevalence of Lynch syndrome mutations in a Canadian hereditary cancer clinic population, and to determine the effectiveness of the program’s referral criteria and testing algorithm.
A retrospective chart review of all patients who were referred for and received genetic counselling at the BC Cancer Agency’s Hereditary Cancer Program for a family history of colon cancer from August 1, 2004, to September 1, 2006, was performed. Charts were reviewed for referral criteria met, cancer history, whether testing was offered and the outcome of testing.
Lynch syndrome was confirmed or highly suspected in 14.3% of index test patients (eight of 56) by the identification of a deleterious mutation or variant likely to be deleterious in either of the hMLH1 or hMSH2 mismatch repair genes. In the program, the two most effective criteria were a personal diagnosis of two or more primary Lynch syndrome-related cancers (one diagnosed at younger than 50 years of age) or two first-degree relatives with a Lynch syndrome-related cancer (both diagnosed at younger than 50 years of age). The respective positive predictive values of these two criteria were calculated to be 66.7% (95% CI 40% to 93%) and 58.3% (95% CI 30.4% to 86.2%).
The Hereditary Cancer Program developed and successfully implemented an approach that selected individuals at risk for Lynch syndrome with a significant pretest probability of mutation of 14.3%. Improved ascertainment of families with Lynch syndrome will require greater physician awareness of referral criteria, program advances in the testing algorithm and a population-based approach to screening incident colon cancers.
Colon cancer; Genetic testing; Hereditary; HNPCC; Lynch syndrome
Some cases of endometrial cancer are associated with a familial tumor and are referred to as hereditary nonpolyposis colorectal cancer (HNPCC or Lynch syndrome). Such tumors are thought to be induced by germline mutation of the DNA mismatch repair (MMR) gene, but many aspects of the pathology of familial endometrial cancer are unclear and no effective screening method has been established. However, the pathology of endometrial cancer with familial tumor has been progressively clarified in recent studies. At present, about 0.5% of all cases of endometrial cancers meet the clinical diagnostic criteria for HNPCC. A recent analysis of the three MMR genes (hMLH1, hMSH2 and hMSH6) revealed germline mutations in 18 of 120 cases (15.0%) of endometrial cancer with familial accumulation of cancer or double cancer, with a frameshift mutation of the hMSH6 gene being the most common. Many cases with mutation did not meet the current clinical diagnostic criteria for HNPCC, indicating that familial endometrial cancer is often not diagnosed as HNPCC. The results suggest that the hMSH6 gene mutation may be important in carcinogenesis in endometrial cancer and germline mutations of the MMR gene may be more prevalent in cases associated with familial accumulation of cancer. An international large-scale muticenter study is required to obtain further information about the pathology of endometrial cancer as a familial tumor.
HNPCC; Endometrial cancer; DNA mismatch repair gene; hMLH1; hMSH6.
Colorectal, endometrial and upper urinary tract tumours are characteristic for Lynch syndrome (hereditary non-polyposis colon carcinoma, HNPCC). The aim of the present study was to establish whether carriers of mutations in mismatch repair genes MLH1, MSH2 or MSH6 are at increased risk of urinary bladder cancer.
Carriers and first degree relatives of 95 families with a germline mutation in the MLH1 (n=26), MSH2 (n=43), or MSH6 (n=26) gene were systematically questioned about the occurrence of carcinoma. The cumulative risk of cancer occurring before the age of 70 years (CR70) was compared to the CR70 of the general Dutch population. Microsatellite instability (MSI) testing and/or immunohistochemistry (IHC) for mismatch repair proteins was performed on bladder tumour tissue.
Bladder cancer was diagnosed in 21 patients (90% men) from 19 Lynch syndrome families (2 MLH1, 15 MSH2, and 4 MSH6). CR70 for bladder cancer was 7.5% (95% CI 3.1% to 11.9%) for men and 1.0% (95% CI 0% to 2.4%) for women, resulting in relative risks for mutation carriers and first degree relatives of 4.2 (95% CI 2.2 to 7.2) for men and 2.2 (95% CI 0.3 to 8.0) for women. Men carrying an MSH2 mutation and their first degree relatives were at highest risks: CR70 for bladder and upper urinary tract cancer being 12.3% (95% CI 4.3% to 20.3%) and 5.9% (95% CI 0.7% to 11.1%). Bladder cancer tissue was MSI positive in 6/7 tumours and loss of IHC staining was found in 14/17 tumours, indicating Lynch syndrome aetiology.
Patients with Lynch syndrome carrying an MSH2 mutation are at increased risk of urinary tract cancer including bladder cancer. In these cases surveillance should be considered.
Lynch syndrome; HNPCC; urothelial cancer; bladder cancer; MSI; gastroenterology; clinical genetics; genetic screening/counselling; cancer: urological
Background and Aims
Although the clinical phenotype of Lynch syndrome (also known as Hereditary Nonpolyposis Colorectal Cancer) has been well described, little is known about disease in PMS2 mutation carriers. Now that mutation detection methods can discern mutations in PMS2 from mutations in its pseudogenes, more mutation carriers have been identified. Information about the clinical significance of PMS2 mutations is crucial for appropriate counseling. Here, we report the clinical characteristics of a large series of PMS2 mutation carriers.
We performed PMS2 mutation analysis using long range PCR and MLPA for 99 probands diagnosed with Lynch syndrome-associated tumors showing isolated loss of PMS2 by immunohistochemistry. Penetrance was calculated using a modified segregation analysis adjusting for ascertainment.
Germline PMS2 mutations were detected in 62% of probands (n = 55 monoallelic; 6 biallelic). Among families with monoallelic PMS2 mutations, 65.5% met revised Bethesda guidelines. Compared with the general population, in mutation carriers, the incidence of colorectal cancer was 5.2 fold higher and the incidence of endometrial cancer was 7.5 fold higher. In North America, this translates to a cumulative cancer risk to age 70 of 15–20% for colorectal cancer, 15% for endometrial cancer, and 25–32% for any Lynch syndrome-associated cancer. No elevated risk for non-Lynch syndrome-associated cancers was observed.
PMS2 mutations contribute significantly to Lynch syndrome but the penetrance for monoallelic mutation carriers appears to be lower than that for the other mismatch repair genes. Modified counseling and cancer surveillance guidelines for PMS2 mutation carriers are proposed.
PMS2; Lynch syndrome; HNPCC; penetrance
Background and Aims
Clinical genetic testing can help direct cancer screening for members of Lynch Syndrome families; however there is limited information about family communication of genetic test results.
174 probands who had genetic testing for Lynch Syndrome were enrolled through 4 U.S. cancer genetics clinics. Subjects were asked whether they had disclosed their genetic test results to first, second and third-degree relatives. Univariate and multivariate analyses were used to identify clinical and demographic factors associated with informing immediate and extended family of genetic test results.
171/174 probands (98% [95%CI: 95%-100%]) reported they had disclosed their genetic test result to a first-degree relative. Communication of test results to other relatives occurred significantly less often, with only 109 of 162 (67% [95%CI: 59%-74%]) subjects with second or third-degree relatives sharing their results. Individuals with a pathogenic mutation were significantly more likely to inform distant relatives than were subjects with a negative or indeterminate test result (OR 2.49 [95% CI: 1.14-5.40]). Probands' age, gender, and cancer status did not influence communication of genetic test results. Lack of closeness and concerns that relatives would worry or not understand the implications of test results were the primary reasons for not sharing genetic test results.
Most individuals who undergo genetic testing for Lynch syndrome share their test results with first-degree family members; however these results reach more distant relatives significantly less often. Interventions to improve communication of genetic test results to members of the extended family are necessary to provide the optimal cancer prevention care to at-risk families.
Background and aims
Early recognition of patients at risk for Lynch syndrome is critical but often difficult. Recently, a predictive algorithm -the PREMM1,2 model- has been developed to quantify the risk of carrying a germline mutation in the mismatch repair (MMR) genes, MLH1 and MSH2. However, its performance in an unselected, population-based colorectal cancer population as well as its performance in combination with tumor MMR testing are unknown.
We included all colorectal cancer cases from the EPICOLON study, a prospective, multicenter, population-based cohort (n=1,222). All patients underwent tumor microsatellite instability analysis and immunostaining for MLH1 and MSH2, and those with MMR deficiency (n=91) underwent tumor BRAF V600E mutation analysis and MLH1/MSH2 germline testing.
The PREMM1,2 model with a ≥5% cut-off had a sensitivity, specificity and positive predictive value (PPV) of 100%, 68% and 2%, respectively. The use of a higher PREMM1,2 cut-off provided a higher specificity and PPV, at expense of a lower sensitivity. The combination of a ≥5% cut-off with tumor MMR testing maintained 100% sensitivity with an increased specificity (97%) and PPV (21%). The PPV of a PREMM1,2 score ≥20% alone (16%) approached the PPV obtained with PREMM1,2 score ≥5% combined with tumor MMR testing. In addition, a PREMM1,2 score of <5% was associated with a high likelihood of a BRAF V600E mutation.
The PREMM1,2 model is useful to identify MLH1/MSH2 mutation carriers among unselected colorectal cancer patients. Quantitative assessment of the genetic risk might be useful to decide on subsequent tumor MMR and germline testing.
Single-gene germline mutations conferring a high lifetime risk of CRC account for up to 6% of all CRC cases. The most widely studied monogenic colorectal cancer syndromes include Familial Adenomatous Polyposis (FAP) and Lynch syndrome. However, additional syndromes continue to be defined and new predisposition genes are continuing to be identified.
Most recently, MYH associated polyposis (MAP) and an “Atypical Lynch syndrome” related to the presence of MSH6 mutations have been linked to an increased risk of CRC. In this review, we summarize basic information related to these newly recognized gene mutations, including the accumulating data on the prevalence and penetrance of deleterious mutations, as well as the management options for identified carriers and their families.
Recognizing these heritable syndromes is essential and predictive genetic testing will continue to transform the field of cancer risk assessment by offering the opportunity to focus on more precise risk management and cancer prevention.
Lynch syndrome confers increased risk for various malignancies, including colorectal cancer. Colonoscopic surveillance programs have led to reduced incidence of colorectal cancer and reduced mortality from colorectal cancer. Colonoscopy every 1–2 years beginning at age 20–25, or 10 years earlier than the first diagnosis of colorectal cancer in a family, with annual colonoscopy after age 40, is the recommended management for mutation carriers. Screening programs have reduced colon cancer mortality, but interval cancers may occur.
We describe a 48-year-old woman with Lynch syndrome who was found to have an adenoma with invasive colorectal cancer within one year after a normal colonoscopy.
Our patient illustrates two current concepts about Lynch syndrome: 1) adenomas are the cancer precursor and 2) such adenomas may be “aggressive,” in the sense that the adenoma progresses more readily and more rapidly to carcinoma in this setting compared to usual colorectal adenomas. Our patient’s resected tumor invaded only into submucosa and all lymph nodes were negative; in that sense, she represents a success for annual colonoscopic surveillance. Still, this case does raise the question of whether advanced imaging techniques are advisable for surveillance colonoscopy in these high-risk patients.
Lynch syndrome; Colorectal carcinoma, Surveillance
Patients with a positive family history have an increased risk of colorectal cancer (CRC) and, in many countries, more intensive screening regimens, sometimes involving the use of colonoscopy as opposed to sigmoidoscopy or fecal occult blood testing, are recommended. This review discusses current screening guidelines in the United States and other countries, data on the magnitude of CRC risk in the presence of a family history and the efficacy of recommended screening programs, as well as ancillary issues such as compliance, cost-effectiveness and accuracy of family history ascertainment. We focus on the relatively common “sporadic” family histories of CRC, which typically imparts a mild to moderate elevation in the risk for CRC development in the proband. Defined familial syndromes associated with extremely high risks of CRC, such as hereditary non-polyposis colorectal syndrome or familial adenomatous polyposis, require specialized management approaches and are beyond the scope of this article. We will also not discuss colonoscopic surveillance in patients with a personal history of adenomas or CRC.
Colon cancer screening; Family history; Colonoscopy; Colon polyp
Lynch syndrome is associated with inherited germline mutations in mismatch repair (MMR) genes. Genetic testing in high-risk individuals may yield indeterminate results if no mutation is found or if a mutation of unclear pathogenic significance is observed. There are limited data regarding how well patients with Lynch syndrome understand the clinical implications of genetic test results. This study examines colorectal cancer (CRC) risk perception in individuals tested for MMR mutations and identifies the factors associated with an appropriate interpretation of their cancer risk.
Patients and Methods
A total of 159 individuals who met the Revised Bethesda Guidelines and had previously undergone genetic testing completed a questionnaire eliciting demographic data, cancer history, genetic test results, and an estimate of their CRC risk. Associations between clinical factors, genetic test results, and CRC risk perception were explored using multivariable analyses.
Of the 100 individuals with a pathogenic mutation (true positive), 90 (90%) correctly estimated their CRC risk as “high” or “very high” compared with other individuals their age. However, only 23 (62%) of 37 individuals with an indeterminate genetic test result correctly estimated their risk. Individuals with a history of Lynch syndrome–associated cancer (odds ratio [OR], 0.1; 95% CI, 0.1 to 0.6) or indeterminate genetic test results (OR, 0.2; 95% CI, 0.1 to 0.6) were significantly less likely to estimate their CRC risk as increased.
Patients at risk for Lynch syndrome with an indeterminate genetic test result may be falsely reassured. It is important that health care providers continue to discuss the implications of uninformative results on lifetime cancer risk.