Exercise once again tops the list of what women can do to help reduce their risk of breast cancer. The higher the activity, the better, with five hours a week of moderate physical activity such as brisk walking cutting breast cancer risk for postmenopausal women, according to the ongoing Nurses Health Study. The research was based on surveys of 95,396 postmenopausal women who were interviewed every two to four years since 1986. The results were the same regardless of receptor status (hormone-positive or hormone-negative), body mass index (BMI) and hormone replacement therapy (HRT). The study was published in the October 25, 2010 issue of the Archives of Internal Medicine.