CIGARETTE-SMOKING AND URINARY ESTROGEN EXCRETION IN PREMENOPAUSAL ANDPOSTMENOPAUSAL WOMEN

Cigarette smoking is associated with a reduction in the risk for endom etrial cancer in postmenopausal women and it has been suggested that t his is because smoking has an anti-oestrogenic effect. To investigate this, concentrations of oestrone, oestradiol and oestriol were measure d in 24 h urine samples from 167 premenopausal women (53 smokers, 114 non-smokers) and 200 post-menopausal women (54 smokers, 146 non-smoker s). Among premenopausal women there were no significant differences in oestrogen excretion between smokers and non-smokers. Among post-menop ausal women, geometric mean excretion rates for oestrone and oestradio l did not differ significantly between groups, but oestriol excretion was 19% lower (95% confidence interval -34% to -1%) in smokers than in non-smokers. This may partly explain the reduced risk for endometrial cancer among post-menopausal smokers.