BACKGROUND: Alcohol intake may influence breast cancer risk in women through hormonal changes, but the evidence to date is inconclusive. We investigated cross-sectional associations between habitual alcohol intake and serum concentrations of testosterone, SHBG (sex hormone binding globulin), IGF-1 (insulin-like growth factor-1) and oestradiol (pre-menopausal women only) in UK Biobank. METHODS: We included 30,557 pre-menopausal and 134,029 post-menopausal women aged between 40-69 years when recruited between 2006 and 2010. At their initial assessment visit, habitual alcohol intake was assessed using a touchscreen questionnaire, and serum hormone concentrations were assayed. Multivariable linear regression analysis was performed. RESULTS: Per 10 g/day increment in alcohol intake, testosterone concentration was 3.9% (95% CI: 3.3%, 4.5%) higher in pre-menopausal women and 2.3% (1.8%, 2.7%) higher in post-menopausal women (pheterogeneity<0.0001); SHBG concentration was 0.7% (0.2%, 1.1%) higher in pre-menopausal women and 2.4% (2.2%, 2.6%) lower in post-menopausal women (pheterogeneity<0.0001); and IGF-1 concentration was 1.9% (1.7%, 2.1%) lower in pre-menopausal women and 0.8% (0.6%, 0.9%) lower in post-menopausal women (pheterogeneity<0.0001). In pre-menopausal women, there was no significant overall association of alcohol with oestradiol but a positive association was observed in the early and mid-luteal phases: 1.9% (95% CI: 0.2%, 3.6%) and 2.4% (95% CI: 0.7%, 4.2%) higher respectively. CONCLUSIONS: This study confirms significant but modest associations between alcohol intake and hormones, with evidence of heterogeneity by menopausal status. IMPACT: The findings facilitate better understanding of whether alcohol intake influences hormone concentrations, but further work is necessary to fully understand the mechanisms linking alcohol with cancer risk.
Cancer Epidemiol Biomarkers Prev