Estrogen Metabolizing Polymorphisms and Breast Cancer Risk Among Older White Women
Objective. To investigate breast cancer risk according to metabolizing genes polymorphisms in older women. Methods. A subset (43.8%) of 4248 older, white women from the Study of Osteoporotic Fractures (SOF) were genotyped for the catechol-O-methyltransferase (COMT) Val108Met polymorphism and the CYP1A1*2C locus. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations between genotypes and breast cancer while controlling for potential confounders. Results. During a mean follow up of 12.4 years, 252 women (5.9%) developed breast cancer. The HR (95% CI) for breast cancer was 1.24 (0.87–1.75) for COMT Val/Met and 1.35 (0.93–1.97) for COMT Met/Met . No interactions with lifestyle and reproductive factors were found. The HR associated with the CYP1A1*2C Val allele was 0.80 (0.46, 1.39) with little evidence for interactions with lifestyle or reproductive factors.  Conclusions. Among older white women, neither the COMT Val108/158Met polymorphism nor the CYP1A*2C Val allele plays a major role in breast cancer risk either alone or in combination with lifestyle and reproductive factors.