One-carbon metabolism biomarkers and risk of colon and rectal cancers

Abstract

Background: Folate intake has been associated with reduced colorectal cancer risk; however, few studies have prospectively examined circulating folate or other related one-carbon biomarkers. Methods: We conducted a nested case-control study within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort of 50-to 69-year-old Finnish men to investigate associations between serum folate, vitamin B6, vitamin B12, riboflavin, and homocysteine and risk of colon and rectal cancers. Controls were alive and cancer-free at the time of case diagnosis and matched 1:1 on age and date of baseline fasting serum collection with cases (152 colon and 126 rectal cancers). Multivariate-adjusted odds ratios and 95% confidence intervals were calculated using conditional logistic regression. Results: Serum vitamin B6 was inversely associated with colon cancer [odds ratio, 0.30 (95% confidence interval, 0.11-0.82) in the highest versus lowest quintile]. An increased risk of colon cancer was suggested for men in the middle quintile of serum folate, but without indication of a dose-response relationship. None of the other serum biomarkers were associated with colon or rectal cancer, and we observed no interactions with alcohol consumption or methionine or protein intake. A priori combinations of the five one-carbon serum biomarkers provided no clear evidence to support a collective influence on colorectal cancer risk. Conclusions: Our results support the hypothesis that higher vitamin B6 status may play a role in inhibiting colon cancer carcinogenesis; however, folate and other one-carbon related biomarkers were not associated with colon or rectal cancer. Copyright © 2008 American Association for Cancer Research.