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Objective: Epidemiologic evidence suggests a positive association between body mass, adult height, and postmenopausal breast cancer. However, most studies have not been large enough to examine the association across a very wide range of body mass or height, and few studies have assessed the relationship between body mass or height and postmenopausal breast cancer mortality., Methods: The relation between body mass index (BMI) and height and postmenopausal breast cancer mortality was examined in the American Cancer Society's Cancer Prevention Study II (CPS-II), a large prospective mortality study of US adults enrolled in 1982. After 14 years of follow-up, 2852 breast cancer deaths were observed among 424,168 postmenopausal women who were cancer-free at interview. Cox proportional hazards modeling was used to estimate relative risks and to control for potential confounding., Results: Breast cancer mortality rates increased continually and substantially with increasing BMI (rate ratio (RR) = 3.08, 95% confidence interval (CI) = 2.09-4.51 for BMI > 40.0 compared to BMI 18.5-20.49). If causal, the multivariate-adjusted RR estimates in this study correspond to approximately 30-50% of breast cancer deaths among postmenopausal women in the US population being attributable to overweight. Breast cancer mortality also increased with increasing height up to 66 inches with RR= 1.64, (95% CI = 1.23-2.18) in women 66 inches tall compared to those <60 inches., Conclusions: Postmenopausal obesity is an important and potentially avoidable predictor of fatal breast cancer in this study. These results underscore the importance of maintaining moderate weight throughout adult life.

Objective: To investigate the hypothesis that tubal sterilization is associated with a reduced risk of breast cancer., Methods: We examined this hypothesis in a large prospective study of US adults. After 14 years of mortality follow-up, 3837 deaths from breast cancer were observed in a cohort of 619,199 women who were cancer-free at study entry in 1982., Results: Cox proportional hazards models (adjusted for multiple breast cancer risk factors) showed a significant inverse association between tubal sterilization and breast cancer mortality (adjusted rate ratio (RR) = 0.82, 95% confidence interval (CI) 0.70-0.96). Women who were sterilized before age 35 had a lower risk (adjusted RR = 0.69, 95% CI 0.53-0.88) than women who were sterilized at 35 years of age or older (adjusted RR = 0.92, 95% CI 0.75-1.13). Also, sterilizations performed before 1975 resulted in a lower risk (RR = 0.75, 95% CI 0.62-0.91) than those performed during or after 1975 (RR = 0.98, 95% CI 0.74-1.29), possibly reflecting the likelihood of greater tissue damage with earlier procedures., Conclusions: These results suggest that tubal sterilization may lower subsequent risk of breast cancer, especially among women who are sterilized at a relatively young age. Additional studies are needed to confirm or refute these findings.