A COHORT STUDY OF ALCOHOL-CONSUMPTION AND RISK OF BREAST-CANCER

The association between alcohol consumption and breast cancer risk was examined in 519 newly incident, histologically confirmed cases of bre ast cancer diagnosed between 1982 and 1987 within a cohort of 56,837 w omen enrolled in the Canadian National Breast Screening Study. These w omen had completed a self-administered food frequency questionnaire in cluding alcohol consumption at enrollment into the study prior to thei r breast cancer diagnosis. For the total cohort, only a weak associati on between total alcohol consumption and breast cancer risk is observe d, the adjusted relative risk for those drinking 30 or more g/day bein g 1.22 (95% confidence interval (Cl) 0.78-1.90) compared with nondrink ers. There is some evidence for a positive association in women who we re premenopausal at the time of enrollment for whom there was a monoto nic increase in risk with increasing alcohol intake. Compared with non drinkers, the adjusted relative risk for alcohol consumption of betwee n 0 and <10 g of alcohol daily was 1.11 (95% Cl C.71-1.71), between 10 and <20 g was 1.37 (95% Cl 0.79-2.36), between 20 and <30 g was 1.51 (95% Cl 0.80-2.86), and greater-than-or-equal-to 30 g was 1.86 (95% Cl 0.96-3.66; p (trend) = 0.07). These findings contrasted with the resu lts for postmenopausal women where there appeared to be no evidence of any relation. The association in premenopausal women is generally rea sonably consistent with that of other studies that have found positive associations with alcohol intake.