Tubal ligation and risk of breast cancer

Although it has been demonstrated in previous studies that tubal ligation c an have widespread effects on ovarian function, including a decrease in the risk of subsequent ovarian cancer, few studies have evaluated effects on b reast cancer risk. In a population-based case-control study of breast cance r among women 20-54 years of age conducted in three geographic areas, previ ous tubal ligations were reported by 25.3% of the 2173 cases and 25.8% of t he 1990 controls. Initially it appeared that tubal ligations might impart a slight reduction in risk, particularly among women undergoing the procedur e at young ages (< 25 years). However, women were more likely to have had t he procedure if they were black, less educated, young when they bore their first child, or multiparous. After accounting for these factors, tubal liga tions were unrelated to breast cancer risk (relative risk (RR) = 1.09, 95% confidence interval (CI) 0.9-1.3), with no variation in risk by age at, int erval since. or calendar year of the procedure. The relationship of tubal l igations to risk did not vary according to the presence of a number of othe r risk factors, including menopausal status or screening history. Furthermo re, effects of tubal ligation were similar for all stages at breast cancer diagnosis. Further studies would be worthwhile given the biologic plausibil ity of an association. However, future investigations should include inform ation on type of procedure performed (since this may relate to biologic eff ects) as well as other breast cancer risk factors. (C) 2000 Cancer Research Campaign.