Background: Epidemiological evidence has suggested that cigarette smoking has an effect on estrogen
and androgen levels in women, but the possible mechanisms are not yet fully understood.
The aim of the present study was to investigate the effect of past and current smoking
on the serum levels of total estrone, estradiol, androstenedione, testosterone, sex
hormone binding globulin (SHBG), and prolactin in postmenopausal women differentiated
by current use of hormone replacement therapy (HRT). Methods: Sex hormone concentrations were measured in 2,388 subjects (1,378 current HRT users,
1,010 HRT non-users) recruited as controls in a population-based case-control study
of breast cancer (MARIE). Associations between log transformed hormone levels and
smoking status were assessed separately in users of HRT and in non-users. Geometric
mean concentrations were compared across levels of smoking using multiple linear regression
to account for potential confounders, such as age, parity, BMI, alcohol intake, and
type of menopause. Results: Current smokers had significantly higher adjusted geometric means for total estrone
(51.7, 50.9, 47.7 pg/ml in current, former, never smokers), estradiol (19.9, 19.5,
18.1 pg/ml), androstenedione (1.2, 1.03, 1.1 pg/ml) and SHBG (44.7, 37.5, 37.6 nmol/l)
concentrations and lower prolactin (4.4 5.1, 5.3ng/ml) concentrations compared to
never smokers, in both HRT users and non-users (p<0.05). Total estrone and estradiol
concentrations were also significantly higher among past smokers compared to never
smokers. Testosterone concentrations (0.41, 0.37, 0.39ng/ml) were not associated with
smoking status. Conclusion: These results confirm previous reports that current cigarette smoking increases total
estrone, estradiol, androstenedione, and SHBG levels in postmenopausal women regardless
of current HRT use. The lower prolactin levels could be explained by the inhibition
of prolactin secretion by high levels of dopamine among smokers.
