Risk for women is 1 in 8 throughout life. Obesity is a decreased risk for breast cancer premenopausally. Postmenopausally, this risk factor increases significantly.
Breast feeding for six months reduces a woman's risk for breast cancer.
Regular exercise, bilateral premenopausal oopherectomies all reduce breast cancer risk. Tamoxifen - evaluated in the breast cancer prevention trial. There was an increase in endometrial cancers, though, and there was a significant negative quality of life score. Avoid tamoxifen in individuals with risk for dvt, and also with a history of cva or other cardiovascular diseases. In 1955 the incidence was 45 out of 100,000.