One-carbon metabolism--related nutrients and prostate cancer survival

Background: Folate and other one-carbon metabolism nutrients may influence prostate cancer pathogenesis. Prior studies of these nutrients in relation to prostate cancer incidence have been inconclusive, and none have explored prostate cancer survival. Objective: The objective was to assess whether dietary intakes of folate, riboflavin, vitamin B-6, vitamin B-12, and methionine measured around the time of prostate cancer diagnosis are associated with prostate cancer survival. Design: This population-based prospective study comprised 525 men from Orebro, Sweden, who received a diagnosis of incident prostate cancer between 1989 and 1994 and completed a self-administered food-frequency questionnaire. Record linkages to the Swedish Death Registry enabled all cases to be followed for up to 20 y after diagnosis, and the cause of death was assigned via medical record review. Cox proportional hazards regression was used to calculate multivariable hazard ratios (HRs) and 95% Cls. During a median of 6.4 y of follow-up, 218 men (42%) died of prostate cancer and 257 (49%) of other causes. Results: A comparison of the highest with the lowest quartile showed that vitamin B-6 intake was inversely associated with prostate cancer--specific death (HR: 0.71; 95% CI: 0.46, 1.10; P for trend = 0.08), especially in men with a diagnosis of localized-stage disease (HR; 0.05; 95% CI: 0.01, 0.26; P for trend = 0.0003). However, vitamin B-6 intake was not associated with improved prostate cancer survival among advanced-stage cases (HR: 1.04; 95% CI: 0.64, 1.72; P for trend = 0.87). Folate, riboflavin, vitamin B-12, and methionine intakes were not associated with prostate cancer survival. Conclusion: A high vitamin B-6 intake may improve prostate cancer survival among men with a diagnosis of localized-stage disease.