Folate has important roles in
DNA synthesis, repair, and methylation and is inversely associated with the risk of some
cancers. The authors examined this association among 65,836 men in the American Cancer Society
Cancer Prevention Study II Nutrition Cohort. During 9 years of follow-up, 5,158 men were diagnosed with
prostate cancer.
Folate intakes were estimated from the questionnaire administered at enrollment in 1992-1993, and Cox proportional hazards models were used to calculate hazard rate ratios adjusted for potential confounders. Neither dietary nor total
folate intake was associated with
prostate cancer overall. However, higher
folate levels were associated with a nonsignificant decreased risk of advanced
prostate cancer (multivariate rate ratio=0.78, 95% confidence interval: 0.53, 1.15 for the highest vs. lowest quintiles of dietary
folate and rate ratio=0.79, 95% confidence interval: 0.54, 1.17 for the highest vs. lowest quintile of total
folate). The association was similar for quintiles 2-5, suggesting that only a small increase in
folate intake was needed to alter the risk of advanced
prostate cancer. Because the statistical power of the analysis with advanced
prostate cancer was limited by the low number of cases, further study is needed to establish this association.