An increasing number of women who have been diagnosed with early-stage cancer in 1 breast decide to have both that breast and the other, healthy one removed. Removal of the healthy breast is called contralateral prophylactic mastectomy (CPM). The procedure reduces the chance of developing cancer in the unaffected breast, but most women have a low risk for contralateral breast cancer—for example, the risk in women without a cancer-predisposing genetic mutation is 0.5% to 0.75% per year. Also, CPM does not necessarily improve survival or decrease the risk for cancer spread, and it can affect quality of life. Few studies have examined women's decisions about CPM, including how well-informed they were about the procedure when they decided to have it.