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IT is known that women who smoke have an earlier menopause than those who do not.1 , 2 Noting recent data suggesting that breast cancer might be somewhat less frequent in smokers than in non-smokers,3 4 5 we thought it would be worthwhile to compare the estrogen profiles of smokers and nonsmokers. A difference might shed light on the mechanisms whereby smoking is associated with early menopause and with a reduction in the risk of breast cancer. Smoking histories were obtained from women for whom urinary estrogen concentrations had been determined previously. As compared with nonsmokers and exsmokers, smokers had substantially and significantly lower . . .
MacMahon et al. (Thu,) studied this question.