Estrogen-DNA Adducts and Breast Cancer Risk in Premenopausal Asian Women.

The incidence of breast cancer among premenopausal women has been increasing rapidly in recent decades in East Asia. This case-control study investigated whether estrogen-DNA adducts were associated with breast cancer risk in Taiwan. The control group (n = 146) comprised healthy female volunteers and women with non-proliferative breast disease. The case group (n = 221) comprised women either with proliferative benign breast disease or breast cancer. The ratios of estrogen-DNA adducts to their respective metabolites and conjugates in plasma were analyzed using ultraperformance liquid chromatography and tandem mass spectrometry. The single nucleotide polymorphisms (SNPs) of CYP1A1, CYP1B1, and COMT were genotyped. Logistic regression model was used to compare the estrogen-DNA adduct ratios between the two groups. The estrogen-DNA adduct ratio in the case group was significantly higher than that in the control group (median ratio: 58.52 vs. 29.36, P = 0.004). A multiple logistic regression model demonstrated that a unit increase in the natural log of the estrogen-DNA adduct ratio in premenopausal women was a significant predictor of breast cancer risk, with an estimated hazard ratio of 1.718 (1.444 - 2.046, P < 0.001). However, the CYP1A1, CYP1B1, and COMT SNPs were not associated with the estrogen-DNA adduct ratios. In conclusion, plasma estrogen-DNA adduct ratio was associated with the presence of breast cancer or proliferating benign breast disease in premenopausal women in Taiwan.