The number of patients in Sweden treated with radical prostatectomy for localized prostate cancer has increased exponentially. The extent to which this increase reflects treatment of non-lethal disease detected through PSA screening is unknown.
We undertook a nationwide study of all 18,837 prostate cancer patients treated with radical prostatectomy in Sweden from 1988 to 2008 with complete follow-up through 2009. We compared cumulative incidence curves, fit Cox regression and cure models and performed a simulation study to determine changes in treatment of non-lethal cancer, in cancer-specific survival over time, and effect of lead-time due to PSA screening.
The annual number of radical prostatectomies increased 25-fold during the study period. The five-year cancer-specific mortality decreased from 3.9% (95% CI 2.5 to 5.3) among patients diagnosed between 1988 and 1992 to 0.7% (95% CI 0.4–1.1) among those diagnosed between 1998 and 2002 (p for trend < 0.001). According to the cure model, the risk of not being cured declined by 13% (95% CI 12–14%) with each calendar year. The simulation study indicated that only about half of the improvement in disease-specific survival could be accounted for by lead-time.
Patients overdiagnosed with non-lethal prostate cancer appear to account for a substantial and growing part of the dramatic increase in radical prostatectomies in Sweden but increasing survival rates are likely also due to true reductions in the risk of disease-specific death over time. Because the magnitude of harm and costs due to overtreatment can be considerable, identification of men who likely benefit from radical prostatectomy is urgently needed.
Overdiagnosis; prostate cancer; PSA screening; radical prostatectomy
A growing proportion of men diagnosed with localized prostate cancer detected through prostate-specific antigen testing are dying from causes other than prostate cancer. Temporal trends in specific causes of death among prostate cancer patients have not been well described.
We analyzed causes of death among all incident prostate cancer cases recorded in the nationwide Swedish Cancer Registry (1961–2008; n = 210 112) and in the US Surveillance, Epidemiology, and End Results Program (1973–2008; n = 490 341). We calculated the cumulative incidence of death due to seven selected causes that accounted for more than 80% of the reported deaths (including ischemic heart disease and non–prostate cancer) and analyzed mortality trends by calendar year and age at diagnosis and length of follow-up.
During follow-up through 2008, prostate cancer accounted for 52% of all reported deaths in Sweden and 30% of reported deaths in the United States among men with prostate cancer; however, only 35% of Swedish men and 16% of US men diagnosed with prostate cancer died from this disease. In both populations, the cumulative incidence of prostate cancer–specific death declined during follow-up, while the cumulative incidences of death from ischemic heart disease and non–prostate cancer remained constant. The 5-year cumulative incidence of death from prostate cancer among all men was 29% in Sweden and 11% in the United States.
In Sweden and the United States, men diagnosed with prostate cancer are less likely to die from prostate cancer than from another cause. Because many of these other causes of death are preventable through changes in lifestyle, interventions that target lifestyle factors should be integrated into prostate cancer management.
Whether the genomic rearrangement TMPRSS2:ERG has prognostic value in prostate cancer is unclear.
Among men with prostate cancer in the prospective Physicians’ Health and Health Professionals Follow-Up Studies, we identified rearrangement status by immunohistochemical assessment of ERG protein expression. We used Cox models to examine associations of ERG overexpression with biochemical recurrence and lethal disease (distant metastases or cancer-specific mortality). In a meta-analysis including 47 additional studies, we used random effects models to estimate associations between rearrangement status and outcomes.
The cohort consisted of 1,180 men treated with radical prostatectomy between 1983 and 2005. During a median follow-up of 12.6 years, 266 men experienced recurrence, and 85 men developed lethal disease. We found no significant association between ERG overexpression and biochemical recurrence (HR: 0.99; 95% CI: 0.78-1.26) or lethal disease (HR: 0.93; 95% CI: 0.61-1.43). The meta-analysis of prostatectomy series included 5,074 men followed for biochemical recurrence (1,623 events), and 2,049 men followed for lethal disease (131 events). TMPRSS2:ERG was associated with stage at diagnosis (RR≥T3 vs. T2: 1.23; 95% CI: 1.16-1.30) but not with biochemical recurrence (RR: 1.00; 95% CI: 0.86-1.17) or lethal disease (RR: 0.99; 95% CI: 0.47-2.09).
These results suggest that TMPRSS2:ERG, or ERG overexpression, is associated with tumor stage but does not strongly predict recurrence or mortality among men treated with radical prostatectomy.
This is the largest prospective cohort study to examine associations of ERG overexpression and lethal prostate cancer among men treated with radical prostatectomy.
TMPRSS2:ERG; prostate cancer; gene fusion; biomarker; prognosis
Effective clinical management of prostate cancer (PCA) has been challenged by significant intratumoural heterogeneity on the genomic and pathological levels and limited understanding of the genetic elements governing disease progression1. Here,we exploited the experimental merits of the mouse to test the hypothesis that pathways constraining progression might be activated in indolent Pten-null mouse prostate tumours and that inactivation of such progression barriers in mice would engender a metastasis-prone condition. Comparative transcriptomic and canonical pathway analyses, followed by biochemical confirmation, of normal prostate epithelium versus poorly progressive Pten-null prostate cancers revealed robust activation of the TGFβ/BMP–SMAD4 signalling axis. The functional relevance of SMAD4 was further supported by emergence of invasive, metastatic and lethal prostate cancers with 100% penetrance upon genetic deletion of Smad4 in the Pten-null mouse prostate. Pathological and molecular analysis as well as transcriptomic knowledge-based pathway profiling of emerging tumours identified cell proliferation and invasion as two cardinal tumour biological features in the metastatic Smad4/Pten-null PCA model. Follow-on pathological and functional assessment con-firmed cyclin D1 and SPP1 as key mediators of these biological processes, which together with PTEN and SMAD4, form a four-gene signature that is prognostic of prostate-specific antigen (PSA) biochemical recurrence and lethal metastasis in human PCA. This model-informed progression analysis, together with genetic, functional and translational studies, establishes SMAD4 as a key regulator of PCA progression in mice and humans.
Although dietary fat has been associated with prostate cancer risk, the association between specific fatty acids and prostate cancer survival remains unclear. Dietary intake of 14 fatty acids was analyzed in a population-based cohort of 525 Swedish men with prostate cancer in Örebro County (1989–1994). Multivariable hazard ratios and 95% confidence intervals for time to prostate cancer death by quartile and per standard deviation increase in intake were estimated by Cox proportional hazards regression. Additional models examined the association by stage at diagnosis (localized: T0-T2/M0; advanced: T0-T4/M1, T3-T4/M0). Among all men, those with the highest omega-3 docosahexaenoic acid and total marine fatty acid intakes were 40% less likely to die from prostate cancer (Ptrend = 0.05 and 0.04, respectively). Among men with localized prostate cancer, hazard ratios of 2.07 (95% confidence interval: 0.93, 4.59; Ptrend = 0.03) for elevated total fat, 2.39 (95% confidence interval: 1.06, 5.38) for saturated myristic acid, and 2.88 (95% confidence interval: 1.24, 6.67) for shorter chain (C4-C10) fatty acid intakes demonstrated increased risk for disease-specific mortality for the highest quartile compared with the lowest quartile. This study suggests that high intake of total fat and certain saturated fatty acids may worsen prostate cancer survival, particularly among men with localized disease. In contrast, high marine omega-3 fatty acid intake may improve disease-specific survival for all men.
fatty acids; prostatic neoplasms; survival analysis
Recent studies suggest variation in genes along the vitamin D pathway, as well as vitamin D receptor (VDR) protein levels, may be associated with prostate cancer. As serum vitamin D levels vary by season, we sought to determine whether expression of genes on the vitamin D pathway, assessed in prostate tumor tissue, do the same.
Our study incorporates mRNA expression data from 362 men in the Swedish Watchful Waiting cohort, diagnosed between 1977 and 1999, and 106 men enrolled in the US Physicians’ Health Study (PHS) diagnosed between 1983 and 2004. We also assayed for VDR protein expression among 832 men in the PHS and Health Professionals Follow-up Study cohorts. Season was characterized by date of initial tissue specimen collection categorically and by average monthly ultraviolet radiation levels. One-way analysis of variance was used to examine variation in expression levels of six genes on the vitamin D pathway – VDR, GC, CYP27A1, CYP27B1, RXRα, CYP24A1 – and VDR protein by season, adjusted for age at diagnosis and Gleason grade. Variation was also examined separately among lethal and nonlethal cases.
Tumor expression levels of the six genes did not significantly vary by season of tissue collection. No consistent patterns emerged from subgroup analyses by lethal versus nonlethal cases.
Unlike circulating levels of 25-OH vitamin D, expression levels of genes on the vitamin D pathway and VDR protein did not vary overall by season of tissue collection. Epidemiological analyses of vitamin D gene expression may not be biased by seasonality.
Vitamin D; Vitamin D receptor; prostate cancer; gene expression; seasonality; biomarkers
Acrylamide has been designated by IARC as a “probable human carcinogen.” High levels are formed during cooking of many commonly consumed foods including French fries, potato chips, breakfast cereal, and coffee. Two prospective cohort studies and two case-control studies in Europe found no association between acrylamide intake and prostate cancer. We examined this association in a large prospective cohort of 47,896 U.S. men in the Health Professionals’ Follow-up Study, using updated dietary acrylamide intake from food frequency questionnaires in 1986, 1990, 1994, 1998, and 2002. From 1986 through 2006, we documented 5025 cases of prostate cancer, and 642 lethal cancers. We used Cox proportional hazards models to assess the association between acrylamide intake from diet and prostate cancer risk overall as well as risk of advanced or lethal cancer.
Acrylamide intake ranged from a mean of 10.5 mcg/day in the lowest quintile to 40.1 mcg/day in the highest quintile; coffee and potato products were largest contributors to intake. The multivariate-adjusted relative risk of prostate cancer was 1.02 (95% confidence interval: 0.92–1.13) for the highest versus lowest quintile of acrylamide intake (p-value for trend=0.90). Results were similar when restricted to never smokers and to men who had PSA tests. There was no significant association for dietary acrylamide and risk of lethal, advanced, or high-grade disease, or for different latency periods ranging from 0–4 years to 12–16 years. We found no evidence that acrylamide intake, within the range of U.S. diets, is associated with increased risk of prostate cancer.
Acrylamide; diet; prostate cancer
Adiponectin, an insulin-sensitizing adipokine, is inversely associated with adiposity and prostate cancer risk and progression. However, the role of genetic variation in the adiponectin (ADIPOQ) and receptor genes (ADIPOR1/R2) in prostate cancer is largely unknown.
In a nested case-control study of 1286 cases and 1267 controls within the Physicians' Health Study, we evaluated 29 common single nucleotide polymorphisms (SNPs) in ADIPOQ (n=13), ADIPOR1(n=5) and ADIPOR2(n=11) in relation to the risk of prostate cancer. In subgroups, we also evaluated the association of genotype and circulating adiponectin levels (n=951) and prostate tumor expression of insulin receptor (IR) and insulin-like growth factor 1 (IGF-1R) receptor (n=181).
Among the 12 tagging polymorphisms in ADIPOQ, four (rs266729, rs182052, rs822391, rs2082940) were significantly associated (p<0.05) with overall prostate cancer risk, with no significant difference by tumor grade or clinical stage. Two of the risk SNPs (rs266729, rs182052) plus four other SNPs (rs16861209, rs17366568, rs3774261, rs7639352) were also associated with plasma adiponectin levels and three of these (rs1686109, rs17366568, rs3774261) were also significantly associated with IR expression in prostate tumor tissue. One additional SNP was associated with IGF1-R tumor tissue expression (rs16861205). None of the 16 variants in ADIPOR1/R2 were related to cancer risk or circulating adiponectin levels.
Common variants in the adiponectin gene were associated with prostate cancer risk, plasma adiponectin levels, and IR or IGF-1R expression in the prostate tumor.
These genotype-phenotype associations support the biological relevance of adiponectin for prostate carcinogenesis, particularly in earlier stages of development.
A challenge in prostate cancer (PCa) management is identifying potentially lethal disease at diagnosis. Inflammation, focal prostatic atrophy and prostatic intraepithelial neoplasia (PIN) are common in prostate tumor specimens, but it is not clear whether these lesions have prognostic significance.
We conducted a case-control study nested in a cohort of men diagnosed with stage T1a-b PCa through transurethral resection of the prostate in Sweden. Cases are men who died of PCa (n=228). Controls are men who survived more than 10 years after PCa diagnosis without metastases (n=387). Slides were assessed for Gleason grade, inflammation, PIN, and four subtypes of focal prostatic atrophy: simple atrophy (SA), post-atrophic hyperplasia (PAH), simple atrophy with cyst formation, and partial atrophy. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) for odds of lethal PCa with multivariable logistic regression.
Chronic inflammation and PIN were more frequently observed in tumors with PAH, but not SA. No specific type of atrophy or inflammation was significantly associated with lethal PCa overall, but there was a suggestion of a positive association for chronic inflammation. Independent of age, Gleason score, year of diagnosis, inflammation, and atrophy type, men with PIN were 89% more likely to die of PCa (95% CI:1.04-3.42).
Our data demonstrate that PIN, and perhaps presence of moderate or severe chronic inflammation, may have prognostic significance for PCa.
Lesions in tumor adjacent tissue, and not just the tumor itself, may aid in identification of clinically relevant disease.
Prostate adenocarcinoma; Chronic inflammation; Post-atrophic hyperplasia; Lethal prostate cancer
The association of vitamin D status with prostate cancer is controversial; no association has been observed for overall incidence, but there is a potential link with lethal disease.
We assessed prediagnostic 25-hydroxyvitamin D [25(OH)D] levels in plasma, variation in vitamin D–related genes, and risk of lethal prostate cancer using a prospective case–control study nested within the Health Professionals Follow-up Study. We included 1260 men who were diagnosed with prostate cancer after providing a blood sample in 1993–1995 and 1331 control subjects. Men with prostate cancer were followed through March 2011 for lethal outcomes (n = 114). We selected 97 single-nucleotide polymorphisms (SNPs) in genomic regions with high linkage disequilibrium (tagSNPs) to represent common genetic variation among seven vitamin D–related genes (CYP27A1, CYP2R1, CYP27B1, GC, CYP24A1, RXRA, and VDR). We used a logistic kernel machine test to assess whether multimarker SNP sets in seven vitamin D pathway–related genes were collectively associated with prostate cancer. Tests for statistical significance were two-sided.
Higher 25(OH)D levels were associated with a 57% reduction in the risk of lethal prostate cancer (highest vs lowest quartile: odds ratio = 0.43, 95% confidence interval = 0.24 to 0.76). This finding did not vary by time from blood collection to diagnosis. We found no statistically significant association of plasma 25(OH)D levels with overall prostate cancer. Pathway analyses found that the set of SNPs that included all seven genes (P = .008) as well as sets of SNPs that included VDR (P = .01) and CYP27A1 (P = .02) were associated with risk of lethal prostate cancer.
In this prospective study, plasma 25(OH)D levels and common variation among several vitamin D–related genes were associated with lethal prostate cancer risk, suggesting that vitamin D is relevant for lethal prostate cancer.
The safety of antioxidant supplements during radiation therapy (RT) for cancer is controversial. Antioxidants could potentially counteract the pro-oxidant effects of RT and compromise therapeutic efficacy. We performed a prospective study nested within the Physicians' Health Study (PHS) randomized trial to determine if supplemental antioxidant use during RT for prostate cancer is associated with an increased risk of prostate cancer death or metastases.
Methods and Materials
383 PHS participants received RT for prostate cancer while randomized to beta-carotene (50 mg on alternate days), or placebo. The primary endpoint was time from RT to lethal prostate cancer, defined as prostate cancer death or bone metastases. The Kaplan-Meier method was used to estimate survival probabilities, and the log-rank test to compare groups. Cox proportional hazards regression was used to estimate the effect of beta-carotene compared with placebo during RT.
With a median follow-up of 10.5 years, there was no significant difference in risk of lethal prostate cancer with use of beta-carotene during RT compared with placebo (HR=0.72; 95% CI, 0.42 to 1.24; P=0.24). After adjusting for age at RT, PSA, Gleason score, and clinical stage, the difference remained non-significant. The 10-year freedom from lethal prostate cancer was 92% (95% CI, 87-95%) in the beta-carotene group and 89% (95% CI, 84-93%) in the placebo group.
Use of the supplemental antioxidant, beta-carotene, during RT was not associated with an increased risk of prostate cancer death or metastases. This study suggests a lack of harm from supplemental beta-carotene during radiation therapy for prostate cancer.
Antioxidants; prostate cancer; vitamins; beta-carotene; outcomes
To examine whether fish and fish oil consumption across the lifespan is associated with a lower risk of prostate cancer.
The study was nested among 2268 men aged 67–96 years in the AGES-Reykjavik cohort study. In 2002 to 2006, dietary habits were assessed, for early life, midlife and later life using a validated food frequency questionnaire. Participants were followed for prostate cancer diagnosis and mortality through 2009 via linkage to nationwide cancer- and mortality registers. Adjusting for potential confounders, we used regression models to estimate odds ratios (ORs) and hazard ratios (HRs) for prostate cancer according to fish and fish oil consumption.
Among the 2268 men, we ascertained 214 prevalent and 133 incident prostate cancer cases, of which 63 had advanced disease. High fish consumption in early- and midlife was not associated with overall or advanced prostate cancer. High intake of salted or smoked fish was associated with a 2-fold increased risk of advanced prostate cancer both in early life (95% CI: 1.08, 3.62) and in later life (95% CI: 1.04, 5.00). Men consuming fish oil in later life had a lower risk of advanced prostate cancer [HR (95%CI): 0.43 (0.19, 0.95)], no association was found for early life or midlife consumption.
Salted or smoked fish may increase risk of advanced prostate cancer, whereas fish oil consumption may be protective against progression of prostate cancer in elderly men. In a setting with very high fish consumption, no association was found between overall fish consumption in early or midlife and prostate cancer risk.
Whether milk and dairy intake after a prostate cancer diagnosis is associated with a poorer prognosis is unknown. We investigated post-diagnostic milk and dairy intake in relation to risk of lethal prostate cancer (metastases and prostate cancer death) among participants in the Health Professionals Follow-Up Study.
The cohort consisted of 3,918 men diagnosed with apparently localized prostate cancer between 1986 and 2006, and followed to 2008. Data on milk and dairy intake were available from repeated questionnaires. We used Cox proportional hazards models to calculate hazard ratios (HR) and 95% confidence intervals (CI) of the association between post-diagnostic milk and dairy intake and prostate cancer outcomes.
We ascertained 229 prostate cancer deaths and an additional 69 metastases during follow-up. In multivariate analysis, total milk and dairy intakes after diagnosis were not associated with a greater risk of lethal prostate cancer. Men with the highest versus lowest intake of whole milk were at an increased risk of progression (HR 2.15; 95% CI: 1.28-3.60; P trend<0.01). Men in the highest versus lowest quintile of low-fat dairy intake were at a decreased risk of progression (HR 0.62; 95% CI: 0.40-0.95; P trend=0.07).
With the exception of whole milk, our results suggest that milk and dairy intake after a prostate cancer diagnosis is not associated with an increased risk of lethal prostate cancer.
This is the first larger prospective study investigating the relation between post-diagnostic milk and dairy intake and risk of lethal prostate cancer.
Fusion of the androgen receptor-regulated (AR-regulated) TMPRSS2 gene with ERG in prostate cancer (PCa) causes androgen-stimulated overexpression of ERG, an ETS transcription factor, but critical downstream effectors of ERG-mediating PCa development remain to be established. Expression of the SOX9 transcription factor correlated with TMPRSS2:ERG fusion in 3 independent PCa cohorts, and ERG-dependent expression of SOX9 was confirmed by RNAi in the fusion-positive VCaP cell line. SOX9 has been shown to mediate ductal morphogenesis in fetal prostate and maintain stem/progenitor cell pools in multiple adult tissues, and has also been linked to PCa and other cancers. SOX9 overexpression resulted in neoplasia in murine prostate and stimulated tumor invasion, similarly to ERG. Moreover, SOX9 depletion in VCaP cells markedly impaired invasion and growth in vitro and in vivo, establishing SOX9 as a critical downstream effector of ERG. Finally, we found that ERG regulated SOX9 indirectly by opening a cryptic AR-regulated enhancer in the SOX9 gene. Together, these results demonstrate that ERG redirects AR to a set of genes including SOX9 that are not normally androgen stimulated, and identify SOX9 as a critical downstream effector of ERG in TMPRSS2:ERG fusion–positive PCa.
To determine whether consumption of whole-grain; rye bread, oatmeal, and whole-wheat bread, during different periods of life, is associated with risk of prostate cancer (PCa).
In 2002 to 2006, 2,268 men, aged 67-96 years, reported their dietary habits in the AGES-Reykjavik cohort study. Dietary habits were assessed for early-, mid- , and current life using a validated food frequency questionnaire (FFQ). Through linkage to cancer- and mortality registers, we retrieved information on PCa diagnosis and mortality through 2009. We used regression models to estimate odds ratios (ORs) and hazard ratios (HRs) for PCa according to whole grain consumption, adjusted for possible confounding factors including fish-, fish liver oil-, meat-, and milk intake.
Of the 2,268 men, 347 had or were diagnosed with PCa during follow-up, 63 with advanced disease (stage 3+ or died of PCa). Daily rye bread consumption in adolescence (vs. less than daily) was associated with a decreased risk of PCa diagnosis (OR = 0.76, 95% Confidence interval (CI): 0.59-0.98), and of advanced PCa (OR = 0.47, 95% CI: 0.27-0.84). High intake of oatmeal in adolescence (≥5 vs. ≤4 times/ week) was not significantly associated with risk of PCa diagnosis (OR = 0.99, 95% CI: 0.77-1.27) nor advanced PCa (OR = 0.67, 95% CI: 0.37-1.20). Mid-, and late life consumption of rye bread, oatmeal, or whole-wheat bread was not associated with PCa risk.
Our results suggest that rye bread consumption in adolescence may be associated with reduced risk of PCa, particularly advanced disease.
adolescent; diet; epidemiology; rye bread; prostatic neoplasms; whole-grain; AGES Reykjavik study
Common genetic variants in the Toll-like receptor 4 (TLR4), which is involved in inflammation and immune response pathways, may be important for prostate cancer.
In a large nested case-control study of prostate cancer in the Physicians’ Health Study (1982–2004), 10 single nucleotide polymorphisms (SNPs) were selected and genotyped to capture common variation within the TLR4 gene as well as 5 kilobases up and downstream. Unconditional logistic regression was used to assess associations of these SNPs with total prostate cancer incidence, and with prostate cancers defined as advanced stage/lethal (T3/T4, M1/N1(T1-T4), lethal) or high Gleason grade (7 (4+3) or greater). Cox-proportional hazards regression was used to assess progression to metastases and death among prostate cancer cases.
The study included 1267 controls and 1286 incident prostate cancer cases, including 248 advanced stage/lethal and 306 high grade cases. During a median follow-up of 10.6 years, 183 men died of prostate cancer or developed distant metastases. No statistically significant associations between the TLR4 SNPs were found for total prostate cancer incidence, including SNPs for which an association was reported in other published studies. Additionally, there were no significant associations with TLR4 SNPS and the incidence of advanced stage/lethal, or high grade cancers; nor was there evidence among prostate cancer cases for associations of TLR4 SNPs with progression to prostate cancer specific mortality or bony metastases.
Results from this prospective nested case-control study suggest that genetic variation across TLR4 alone is not strongly associated with prostate cancer risk or mortality.
TLR4; prostate cancer; inflammation; molecular epidemiology
α-Methylacyl-CoA racemase (AMACR) is an enzyme that serves as a diagnostic biomarker of prostate cancer in clinical practice. Recent studies suggest that low AMACR expression is associated with biochemical recurrence and the development of fatal disease.
We conducted a prospective cohort study among 920 men aged 47–84 years, who were diagnosed with prostate cancer in the Physicians’ Health Study and the Health Professionals Follow-up Study cohorts, and whose resected tissue specimens were available for immunohistochemical analysis. We used Cox proportional hazards regression to evaluate the association of AMACR expression with lethal prostate cancer over a 20-year follow-up period.
In total, 68 men died from prostate cancer, and an additional 18 developed bony metastases during follow-up. We found that lower AMACR intensity was associated with higher prostate-specific antigen levels (p=0.003) and more advanced clinical stage (p=0.06) at diagnosis, and a non-significant trend for higher risk of lethal outcomes. The hazard ratio comparing the lowest to the highest quartile of AMACR expression intensity was 1.53 ((95% CI: 0.86, 2.73), p-for-trend across quartiles=0.07); this trend was further attenuated after adjustment for age, Gleason score, stage and cohort with a hazard ratio of 1.24 (95% CI 0.69, 2.22), p-for-trend=0.23.
Low AMACR expression in primary tumor specimens was not independently associated with the development of metastatic and lethal prostate cancer after treatment over a 20-year follow-up period, after adjustment for important clinical covariates at diagnosis.
A common treatment of advanced prostate cancer involves the deprivation of androgens. Despite the initial response to hormonal therapy, eventually all the patients relapse. In the present study, we sought to determine whether dietary polyunsaturated fatty acid (PUFA) affects the development of castration-resistant prostate cancer. Cell culture, patient tissue microarray, allograft, xenograft, prostate-specific Pten knockout and omega-3 desaturase transgenic mouse models in conjunction with dietary manipulation, gene knockdown and knockout approaches were used to determine the effect of dietary PUFA on castration-resistant Pten-null prostate cancer. We found that deletion of Pten increased androgen receptor (AR) expression and Pten-null prostate cells were castration resistant. Omega-3 PUFA slowed down the growth of castration-resistant tumors as compared with omega-6 PUFA. Omega-3 PUFA decreased AR protein to a similar extent in tumor cell cytosolic and nuclear fractions but had no effect on AR messenger RNA level. Omega-3 PUFA treatment appeared to accelerate AR protein degradation, which could be blocked by proteasome inhibitor MG132. Knockdown of AR significantly slowed down prostate cancer cell proliferation in the absence of androgens. Our data suggest that omega-3 PUFA inhibits castration-resistant prostate cancer in part by accelerating proteasome-dependent degradation of the AR protein. Dietary omega-3 PUFA supplementation in conjunction with androgen ablation may significantly delay the development of castration-resistant prostate cancer in patients compared with androgen ablation alone.
The authors investigated whether early-life residency in certain areas of Iceland marked by distinct differences in milk intake was associated with risk of prostate cancer in a population-based cohort of 8,894 men born between 1907 and 1935. Through linkage to cancer and mortality registers, the men were followed for prostate cancer diagnosis and mortality from study entry (in waves from 1967 to 1987) through 2009. In 2002–2006, a subgroup of 2,268 participants reported their milk intake in early, mid-, and current life. During a mean follow-up period of 24.3 years, 1,123 men were diagnosed with prostate cancer, including 371 with advanced disease (stage 3 or higher or prostate cancer death). Compared with early-life residency in the capital area, rural residency in the first 20 years of life was marginally associated with increased risk of advanced prostate cancer (hazard ratio = 1.29, 95% confidence interval (CI): 0.97, 1.73), particularly among men born before 1920 (hazard ratio = 1.64, 95% CI: 1.06, 2.56). Daily milk consumption in adolescence (vs. less than daily), but not in midlife or currently, was associated with a 3.2-fold risk of advanced prostate cancer (95% CI: 1.25, 8.28). These data suggest that frequent milk intake in adolescence increases risk of advanced prostate cancer.
adolescent; diet; Iceland; milk; prostatic neoplasms; risk factors
Disruption of the circadian system has been hypothesized to increase cancer risk, either due to direct disruption of the molecular machinery generating circadian rhythms or due to disruption of parameters controlled by the clock such as melatonin levels or sleep duration. This hypothesis has been studied in hormone-dependent cancers among women, but data are sparse regarding potential effects of circadian disruption on the risk of prostate cancer. This review systematically examines available data evaluating the effects of light at night, sleep patterns, and night shift work on prostate cancer risk.
prostate cancer; circadian disruption; sleep disruption; shift work; melatonin; light at night
We examined patient-reported outcomes among prostate cancer patients managed by watchful waiting (WW) in a nationwide cohort.
Materials and Methods
We collected treatment information and patient-reported outcomes from 1230 prostate cancer patients diagnosed with T1-T2 prostate cancer in the Physicians’ Health Study; 125 were initially managed by WW. Cox proportional-hazards regression was used to identify predictors of treatment initiation among WW patients. Logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI) to assess disease-targeted quality of life by initial treatment or WW.
At 7.3 years’ mean follow-up, 41% of WW patients remained free of treatment while 34% underwent radiotherapy or brachytherapy, 16% underwent primary hormonal therapy, and 10% underwent prostatectomy. Younger age, higher clinical stage, higher Gleason score, and higher PSA at diagnosis predicted progression to treatment. Watchful waiting compared to immediate treatment was associated with less urinary incontinence (3.5% vs 10%) and impotence (68% vs 78%) but more common obstructive urinary symptoms (22% vs 13%) in univariate analyses (p< 0.05 for each), with incontinence and impotence differences remaining significant after adjustment for age, comorbidity, and time after cancer diagnosis. Quality of life outcomes among men who underwent delayed treatment after initially waiting were not worse than among men who underwent immediate treatment.
Our findings suggest quality of life benefits subsequent to WW among select patients with early-stage prostate cancer compared to men treated immediately following diagnosis. Younger age and greater cancer severity at diagnosis predicted progression to treatment.
watchful waiting; prostate cancer; prospective study; quality of life; outcomes
Clinical outcomes in prostate cancer are heterogeneous and given the high prevalence of the disease, there is a pressing need to identify clinically useful markers of prognosis. Many clinical, pathologic, molecular, and genetic factors have been investigated in this capacity though relatively few are routinely used. With a growing understanding of the molecular pathogenesis of prostate cancer, there is the potential that the next generation of makers will prove sufficiently robust to guide the optimal management of men with prostate cancer. Here, we review the various clinical and molecular prognostic determinants in prostate cancer.
prognosis; prostate; gene expression signatures; immunohistochemistry
Data suggest that circulating 25-hydroxyvitamin D [25(OH)D] interacts with the vitamin D receptor (VDR) to decrease proliferation and increase apoptosis for some malignancies, although evidence for prostate cancer is less clear. How VDR expression in tumor tissue may influence prostate cancer progression has not been evaluated in large studies.
Patients and Methods
We examined protein expression of VDR in tumor tissue among 841 patients with prostate cancer in relation to risk of lethal prostate cancer within two prospective cohorts, the Physicians' Health Study and Health Professionals Follow-Up Study. We also examined the association of VDR expression with prediagnostic circulating 25(OH)D and 1,25-dihydroxyvitamin D levels and with two VDR single nucleotide polymorphisms, FokI and BsmI.
Men whose tumors had high VDR expression had significantly lower prostate-specific antigen (PSA) at diagnosis (P for trend < .001), lower Gleason score (P for trend < .001), and less advanced tumor stage (P for trend < .001) and were more likely to have tumors harboring the TMPRSS2:ERG fusion (P for trend = .009). Compared with the lowest quartile, men whose tumors had the highest VDR expression had significantly reduced risk of lethal prostate cancer (hazard ratio [HR], 0.17; 95% CI, 0.07 to 0.41). This association was only slightly attenuated after adjustment for Gleason score and PSA at diagnosis (HR, 0.33; 95% CI, 0.13 to 0.83) or, additionally, for tumor stage (HR, 0.37; 95% CI, 0.14 to 0.94). Neither prediagnostic plasma vitamin D levels nor VDR polymorphisms were associated with VDR expression.
High VDR expression in prostate tumors is associated with a reduced risk of lethal cancer, suggesting a role of the vitamin D pathway in prostate cancer progression.
Prostate-specific antigen screening has led to enormous overtreatment of prostate cancer because of the inability to distinguish potentially lethal disease at diagnosis. We reasoned that by identifying an mRNA signature of Gleason grade, the best predictor of prognosis, we could improve prediction of lethal disease among men with moderate Gleason 7 tumors, the most common grade, and the most indeterminate in terms of prognosis.
Patients and Methods
Using the complementary DNA–mediated annealing, selection, extension, and ligation assay, we measured the mRNA expression of 6,100 genes in prostate tumor tissue in the Swedish Watchful Waiting cohort (n = 358) and Physicians' Health Study (PHS; n = 109). We developed an mRNA signature of Gleason grade comparing individuals with Gleason ≤ 6 to those with Gleason ≥ 8 tumors and applied the model among patients with Gleason 7 to discriminate lethal cases.
We built a 157-gene signature using the Swedish data that predicted Gleason with low misclassification (area under the curve [AUC] = 0.91); when this signature was tested in the PHS, the discriminatory ability remained high (AUC = 0.94). In men with Gleason 7 tumors, who were excluded from the model building, the signature significantly improved the prediction of lethal disease beyond knowing whether the Gleason score was 4 + 3 or 3 + 4 (P = .006).
Our expression signature and the genes identified may improve our understanding of the de-differentiation process of prostate tumors. Additionally, the signature may have clinical applications among men with Gleason 7, by further estimating their risk of lethal prostate cancer and thereby guiding therapy decisions to improve outcomes and reduce overtreatment.
Coffee contains many biologically active compounds, including caffeine and phenolic acids, that have potent antioxidant activity and can affect glucose metabolism and sex hormone levels. Because of these biological activities, coffee may be associated with a reduced risk of prostate cancer.
We conducted a prospective analysis of 47 911 men in the Health Professionals Follow-up Study who reported intake of regular and decaffeinated coffee in 1986 and every 4 years thereafter. From 1986 to 2006, 5035 patients with prostate cancer were identified, including 642 patients with lethal prostate cancers, defined as fatal or metastatic. We used Cox proportional hazards models to assess the association between coffee and prostate cancer, adjusting for potential confounding by smoking, obesity, and other variables. All P values were from two-sided tests.
The average intake of coffee in 1986 was 1.9 cups per day. Men who consumed six or more cups per day had a lower adjusted relative risk for overall prostate cancer compared with nondrinkers (RR = 0.82, 95% confidence interval [CI] = 0.68 to 0.98, Ptrend = .10). The association was stronger for lethal prostate cancer (consumers of more than six cups of coffee per day: RR = 0.40, 95% CI = 0.22 to 0.75, Ptrend = .03). Coffee consumption was not associated with the risk of nonadvanced or low-grade cancers and was only weakly inversely associated with high-grade cancer. The inverse association with lethal cancer was similar for regular and decaffeinated coffee (each one cup per day increment: RR = 0.94, 95% CI = 0.88 to 1.01, P = .08 for regular coffee and RR = 0.91, 95% CI = 0.83 to 1.00, P = .05 for decaffeinated coffee). The age-adjusted incidence rates for men who had the highest (≥6 cups per day) and lowest (no coffee) coffee consumption were 425 and 519 total prostate cancers, respectively, per 100 000 person-years and 34 and 79 lethal prostate cancers, respectively, per 100 000 person-years.
We observed a strong inverse association between coffee consumption and risk of lethal prostate cancer. The association appears to be related to non-caffeine components of coffee.