Chlebowski RT, et al. - In view of the observation that obesity is an established risk factor for postmenopausal breast cancer, researchers assessed whether weight change influence the breast cancer risk in postmenopausal women in the Women’s Health Initiative Observational Study. They measured body weight and height and calculated body mass index (BMI) at baseline and year 3 in postmenopausal women (n = 61,335) who had no prior breast cancer and had a normal mammogram. During a mean follow-up of 11.4 years with 3061 incident breast cancers, significantly lower risk of breast cancer was noted in women with weight loss (n = 8175) compared to those whose weight remained stable (n = 41,139) with no interaction by BMI. Findings thereby suggest that achieving weight loss in postmenopausal women may reduce their breast cancer risk.