CIGARETTE-SMOKING AND THE RISK OF BREAST-CANCER

The relation between cigarette smoking and breast cancer risk was inve stigated in a multicentric case-control study conducted in Italy on 2, 569 women with incident, histologically confirmed breast cancer and 2, 588 control women admitted to hospital for acute, non-neoplastic, non- hormonal, non-gynaecological or smoking-related conditions, Compared w ith women who had never smoked, current smokers had a multivariate odd s ratio (OR) of 0.84 [95% confidence interval (CI) 0.7-1.0] and former smokers an OR of 1.14 (5% CT 0.9-1.4), while the OR for ever vs never smokers was 0.93 (95% CI 0.8-1.1). The ORs were 1.02 for < 5 cigarett es per day, 0.99 for 5-14 cigarettes per day, 0.78 for 15-24 cigarette s per day and 1.18 for greater than or equal to 25 cigarettes per day, No consistent pattern of risk was observed according to duration of s moking, age at starting and time since starting smoking, Compared with never smokers, former smokers had ORs of 1.45 for < 3 years since sto pping smoking, 1.79 for 3-6 years, 1.16 for 7-15 years and 0.74 for gr eater than or equal to 16 years, No heterogeneity emerged across strat a of selected covariates, Thus, this study, one of the largest conduct ed in Europe to date, does not support the presence of any association of practical importance between cigarette smoking and breast cancer r isk.