CIGARETTE SMOKING AND BREAST CANCER1

Abstract
To investigate the relationship of smoking to breast cancer ilek, the authors conducted a case-control study involvIng 1,547 patients and 1,930 controls identified between 1973 and 1980 through a nationwide screening program. There was no evidence that smoking affected risk (relative risk (RR) = 1.2), nor were there any apparent relationships with more detailed exposure measures. No substantial variations in risk were noted by menopausal status; in particular, there was no support for the notion that smoking Is associated with a reduced risk among naturalty menopausal women (RR = 1.1). In addition, the data provided no general evidence that smokers experience an earlier menopause than nonsmokers, even when heavy smoking was considered. Evaluation of a number of sources of confounding and effect modification failed to after the conclusion that smoking status does not appear to alter breast cancer risk among this population.