Meat mutagens and breast cancer in postmenopausal women--a cohort analysis.

BACKGROUND Mutagenic compounds produced when meats are cooked at high temperatures have been hypothesized to increase risk of breast cancer. METHODS We examined the association between intakes of the heterocyclic amines (HCA) MeIQx (2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline), PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine), DiMeIQx (2-amino-3,4,8-trimethylimidazo[4,5-f]), and meat-derived mutagenic (MDM) activity and risk of breast cancer using a cooking method questionnaire administered in 1996 in the Nurses' Health Study. Between 1996 and 2006, 2,317 breast cancer cases were diagnosed during 533,618 person-years. RESULTS Higher intake of HCAs or MDM was not associated with elevated risk of breast cancer [multivariate relative risk and 95% confidence interval for the highest versus lowest quintile: MeIQx: 0.90 (0.79-1.03); PhIP: 0.92 (0.80-1.05); DiMeIQx: 0.92 (0.80-1.05); and MDM: 0.98 (0.85-1.12)]. HCA or MDM was not associated with estrogen receptor-positive/progesterone receptor-positive breast cancer risk either. There was some suggestion of a decreased risk of estrogen receptor-negative/progesterone receptor-negative breast cancer with higher intakes of MeIQx, DiMeIQx, and PhIP, but none of the associations were statistically significant. There was little evidence for an interaction between intake of cruciferous vegetables and HCA or MDM intake and risk of breast cancer. CONCLUSION Higher consumption of mutagens from meats cooked at higher temperature and longer duration was not associated with increased risk of postmenopausal breast cancer. IMPACT Overall prospective data including results from our study do not provide support for a substantial increase in risk of breast cancer with higher intake of HCAs.