Breast cancer epidemiology: An overview

One woman in 8 can be expected to develop breast cancer, the most commonly diagnosed cancer in women as well as the second most common cause of cancer deaths among women. It is estimated that in 1998 180,000 new cases of brea st cancer occurred and that 44,000 women died of the disease. According to the National Cancer Institute (NCI), 84% of women are alive 5 years after b eing diagnosed with breast cancer. Whereas age is the key risk factor for b reast cancer, other factors include age at menarche, family history, nullip arity or having a first full-term birth after the age of 30, and a history of a previous breast biopsy. In addition, a genetic risk factor, the BRCA1 mutation, is associated with only 5% to 10% of breast cancers. Results of t he Breast Cancer Prevention Trial, a chemoprevention trial using tamoxifen and placebo involving 13,000 high-risk participants, demonstrated a 45% dec rease in the incidence of breast cancer. Because of the success of that tri al, a Study of Tamoxifen and Raloxifene (STAR) is scheduled to begin this y ear. The STAR trial will compare tamoxifen with raloxifene to evaluate its ability to reduce the incidence of breast cancer in high-risk postmenopausa l women.