Alcohol intake and endogenous hormones in pre- and post-menopausal women: findings from the UK Biobank.
Tin Tin S., Key TJ., Reeves GK.
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.