Several studies suggest that low dietary intake of folate may be a risk for breast cancer, particularly in women who consume alcohol. Genetic background is also a contributing factor to carcinogenesis. Two polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene, C677T and A1298C, involved in folate metabolism have been inconsistently associated with breast cancer risk. We conducted a nested case-control study (261 cases and 261 controls) within the Washington County, MD Clue II Cohort, to examine the association between dietary folate intake, alcohol intake, polymorphisms in MTHFR and incident breast cancer. The preliminary results of this investigation suggest that dietary folate intake alone is not significantly associated with breast cancer risk. No statistically significant excess risk was observed among women who consumed less than 257 μg folate/day (the median folate intake among controls) and at least one drink/day (OR1.4; 95% CI (0.71-2.69)). Neither polymorphism examined was associated with breast cancer and in preliminary analyses, there was no evidence of interaction between the polymorphisms in MTHFR and the risk of breast cancer. No association was observed between dietary folate intake and breast cancer risk. Observed results did not vary by MTHFR genotype.

[Proc Amer Assoc Cancer Res, Volume 46, 2005]