ABSTRACT
This was a retrospective study of 639 women with a family history of breast cancer who underwent bilateral prophylactic mastectomy at the Mayo Clinic between the years of 1960 and 1993. The women were divided into high-risk (n 214) and moderate-risk (n 425) on the basis of their family history. A non-surgical control group of sisters of those in the high-risk group and the Gail model were used to estimate the expected number of breast cancer cases in these two groups in the absence of prophylactic surgery. Following prophylactic surgery, there was an 89.5% (p 0.001) reduction in risk of breast cancer in the moderate-risk group and a 90% reduction in risk in the high-risk group. These data suggest prophylactic mastectomy is extremely effective at reducing breast cancer risk, even in high-risk women.
