Dietary folate and folate vitamers and the risk of prostate cancer in The Netherlands Cohort Study.
ABSTRACT PURPOSE: The aim of the present study was to examine the association between intake of folate, and specific folate vitamers, and the risk of advanced and total prostate cancer. METHODS: The association between dietary folate and prostate cancer risk was evaluated in The Netherlands Cohort Study (NLCS) on diet and cancer, conducted among 58,279 men ages 55-69 years at baseline. Information on diet was collected at baseline by means of food frequency questionnaires. Incident cases were identified by record linkage with regional cancer registries and the Dutch National Database of Pathology Reports. After 17.3 years of follow-up, 3,669 incident prostate cancer cases, of which 1,290 advanced cases, and 2,336 male subcohort members were available for case-cohort analyses. RESULTS: Dietary folate was not associated with prostate cancer risk, nor with the risk of advanced prostate cancer, among men in the NLCS cohort (HR = 1.05, 95 % CI: 0.87-1.26 and HR = 1.09, 95 % CI: 0.88-1.35, respectively, for the highest quintile of folate intake vs. the lowest quintile). Specific folate vitamers were neither associated with the risk of prostate cancer or risk of advanced prostate cancer. CONCLUSIONS: Our results do not support an association of dietary folate or specific folate vitamers on the risk of prostate cancer, or advanced prostate cancer.
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ABSTRACT: There is conflicting evidence regarding the role of folate on the risk of developing prostate cancer. We performed a systematic review and quantitative meta-analysis of folate blood levels and folate intake, and the risk of prostate cancer. Four electronic databases (Medline, PubMed, Embase and Current Contents Connect) were searched to 11 October 2013, with no language restrictions for observational studies that measured folate intake or blood levels and the risk of prostate cancer. Pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using a random effects model. The dietary folate meta-analysis comprising 11 studies with 15 336 cases and a total sample size of 146 782 found no statistically significant association with prostate cancer, with an OR of 0.97 (95% CI 0.89-1.06). The total folate meta-analysis comprising of 5 studies with 7114 cases and a total sample size of 93 781 also found no statistically significant association with prostate cancer, with an OR of 0.99 (95% CI 0.82-1.19). The blood folate meta-analysis comprising of seven studies with 6122 cases and a total sample size of 10 232 found an increased risk of prostate cancer with high blood folate levels, with an OR of 1.43 (95% CI 1.06-1.93). There was significant heterogeneity (I(2)=79.5%, P<0.01). Removal of an outlier study removed the heterogeneity (I(2)=0.0%, P=0.54) and the association remained significant with an OR of 1.14 (95% CI 1.02-1.28). Dietary and total folate intake do not appear to be significantly associated with the risk of prostate cancer. High blood folate levels are associated with an increased risk of prostate cancer. These conclusions are limited by the predominance of included studies originating from developed countries with mostly Caucasian populations. Further research in populations with a high prevalence of non-Caucasian backgrounds is needed.Prostate Cancer and Prostatic Disease advance online publication, 13 May 2014; doi:10.1038/pcan.2014.16.Prostate cancer and prostatic diseases 05/2014; · 2.10 Impact Factor
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ABSTRACT: PURPOSE: Increased evidence suggests that folate may play a significant role in cancer development. This study investigates the association between levels of serum folate and prostate-specific antigen (PSA), a biomarker for prostate cancer detection. METHODS: Using data from the 2007 to 2010 National Health and Nutrition Examination Survey, a total of 3,293 men aged 40 years and older with serum PSA and folate measures were studied. Total PSA level (tPSA) and percent free/total PSA ratio (%fPSA) were major outcomes. The alternative cutpoints were used to categorize these measures as higher risks of prostate cancer (tPSA: ≥10, ≥4, and ≥2.5 ng/ml; %fPSA: ≤15 and ≤5 %). Serum folate level was analyzed as continuous and as quintiles. Association between serum folate and PSA levels were evaluated by multivariate linear and logistic regressions. RESULTS: Higher serum folate levels were associated with decreased log10-transformed tPSA (β = -001, p = 0.061) and increased %fPSA (β = 0.064, p = 0.012). Adjusting for age, race/ethnicity, socioeconomic status, use of non-steroidal anti-inflammatory drugs, body mass index, and smoking status, higher serum folate (fifth quintile) was associated with lower odds of having higher tPSA (≥10 ng/ml) and lower %fPSA (≤25 %): (tPSA: odds ratio, OR associated with fifth to first quintile of folate level = 0.42; 95 % confidence interval, CI = 0.21, 0.83; p for trend = 0.022 and %fPSA: OR = 0.71; 95 % CI = 0.52, 0.95; p for trend = 0.044). CONCLUSIONS: Results of this study suggest that higher folate status may be protective against elevated PSA levels among men without diagnosed prostate cancer. Additional epidemiologic studies are necessary to confirm our findings and to investigate potential mechanisms.Cancer Causes and Control 05/2013; · 3.20 Impact Factor
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ABSTRACT: PURPOSE: Micronutrients may protect against prostate cancer. However, few studies have had high-quality assessment of both dietary and supplemental consumption of micronutrients, rendering possible different source-specific effects difficult to discern. This study evaluates associations between intake of vitamin C, E, folate, and beta-carotene and prostate cancer risk, focusing on possible different effects of dietary, supplemental, or total intake and on potential effect modification by alcohol intake and BMI. METHODS: Danish prospective cohort study of 26,856 men aged 50-64 years with questionnaire-based information on diet, supplements, and lifestyle. Hazard ratios (HRs) for prostate cancer associated with micronutrient intake were calculated using Cox proportional hazard analyses. RESULTS: During follow-up (1993-2010), 1,571 prostate cancer cases were identified. Supplemental folic acid was inversely associated with prostate cancer risk, notably on a continuous scale [HR 0.88 (95 % CI 0.79-0.98) per 100 μg increase/day]. The risk reduction was largely confined to non-aggressive tumors [HR 0.71 (0.55-0.93) per 100 μg increase/day]. No influence on prostate cancer risk was observed for dietary folate or for the other studied micronutrients, regardless of source. We found no significant effect modification by alcohol intake and BMI in relation to any micronutrient. CONCLUSION: Our study may indicate an inverse association between folic acid and prostate cancer; however, the inverse association was confined to supplemental folic acid and non-aggressive prostate cancer and may thus be a chance finding. Further studies are warranted to evaluate our findings.Cancer Causes and Control 03/2013; · 3.20 Impact Factor