Cigarette Smoking and Endogenous Sex Hormones in Postmenopausal Women

Context: Sex hormones play a key role in women's health, but little is known about lifestyle factors that influence their levels. Objective: The objective of the study was to investigate the relationship between cigarette smoking habits and endogenous sex hormone levels in postmenopausal women. Design and Participants: This was a cross-sectional study among 2030 postmenopausal women aged 55-81 yr from the Norfolk population of the European Prospective Investigation into Cancer. All women were at least 1 yr postmenopausal and not currently using hormone replacement therapy. General linear models were used to examine the relationship between smoking habits and sex hormone levels. Results: Among current smokers, the daily number of cigarettes smoked was associated with increased levels of testosterone (19-37%), free testosterone (19-34%), 17-hydroxprogesterone (17-22%), androstenedione (2-23%), SHBG (6-10%), and estradiol (-2 to 15%). Stratified analysis for body mass index revealed an interaction such that the association with SHBG was restricted to lean women, whereas a smoking-related increase in free estradiol was found only in overweight women. No clear dose-response relationship was observed for estrone, although its levels were highest in heavy smokers. Current smoking habit was associated with a larger difference in sex hormone levels than lifetime cigarette exposure as measured by pack-years. Among former smokers, sex hormones were at levels of never smokers within 1-2 yr of smoking cessation. Conclusions: Cigarette smoking is associated with higher circulating levels of androgens, estrogens, 17-hydroxprogesterone, and SHBG in postmenopausal women. The almost immediate lower levels with smoking cessation may indicate that hormone related disease risks could potentially be modified by changing smoking habits. (J Clin Endocrinol Metab 96: 3184-3192, 2011)