Abstract
BACKGROUND: Alcohol consumption is a consistent risk factor for breast cancer, and evidence suggests premenopausal plasma hormones are associated with breast cancer. METHODS: Plasma concentrations of estradiol, estrone, estrone sulfate, testosterone, androstenedione, progesterone, prolactin, dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), and sex hormone-binding globulin (SHBG) were measured in samples collected in 1996-99. Average alcohol intake was calculated from semiquantitative food frequency questionnaires collected in 1995 and 1999. We used generalized linear models to calculate geometric mean hormone concentrations across alcohol categories and the percentage difference for the highest versus lowest category. RESULTS: Comparing women who consumed >20 g/d with nondrinkers, levels were 25.7% higher for luteal estrone (geometric mean, 106 vs. 84.5 pg/mL; Ptrend = 0.001), 27.2% higher for luteal estradiol (182 vs. 143 pg/mL; Ptrend = 0.006), and 16.8% higher for SHBG (85.6 vs. 73.3 nmol/L; Ptrend = 0.03); concentrations of free testosterone were 17.9% lower (0.16 vs. 0.20 ng/dL; Ptrend = 0.002). Women consuming >10 g/d compared with nondrinkers had 26.5% higher concentrations of follicular estrone sulfate (950 vs. 751 pg/mL; Ptrend = 0.04). We did not observe significant associations between alcohol and the other sex hormones evaluated. Significant positive associations were observed with beer intake, but not other alcohol types, for DHEA (Pinteraction = 0.003) and androstenedione (Pinteraction = 0.006). CONCLUSION: Alcohol consumption was significantly positively associated with plasma luteal estrogen concentrations, but not with androgen levels, nor estrone or estradiol measured in the follicular phase. IMPACT: Differences in premenopausal estrogen levels may contribute to the association between alcohol and breast cancer.