Prophylactic mastectomy: pathologic findings in high-risk patients.

[BACKGROUND] According to recently published data, prophylactic mastectomy (PM) appears to prevent about 90% of the expected malignant neoplasms in women with a family history of breast cancer.

[OBJECTIVES] To identify the frequency of high-risk lesions in PM specimens and to determine occurrence of any new primary breast cancer following PM.

[DESIGN] We performed a retrospective study of women undergoing unilateral or bilateral PM. Medical charts and pathologic findings of 35 patients who underwent bilateral mastectomies at University Hospital, Syracuse, NY, from 1989 to 1996 were reviewed. Patients with biopsy-proven bilateral breast cancer were excluded. Patients were divided into 3 groups: (A) positive family history and no known breast cancer (n = 9), (B) positive family history and contralateral neoplasia (n = 13), and (C) negative family history and contralateral neoplasia (n = 13). These findings were compared with those found in reduction mammoplasty specimens from 10 women at standard risk of breast cancer.

[RESULTS] The mean age of the control group of women undergoing reduction mammoplasty was 38 years. The pathologic specimens demonstrated no significant pathologic findings in 9 and fibrocystic change in 1. In group A, the mean number of affected relatives was 3.1, and the mean age was 38 years. Two of these 9 women had atypical duct hyperplasia and 1 had atypical lobular hyperplasia in their breasts (ie, 33% with high-risk pathologic findings). Of the 13 group B women (mean age, 46.6 years; mean of 2.5 affected relatives and unilateral breast cancer), the contralateral PM specimen contained duct carcinoma in situ in one and invasive ductal cancer in a second (15% with occult malignant neoplasms). In 13 group C patients (mean age, 47.1 years), 3 (23.1%) of the contralateral PM specimens displayed atypical duct hyperplasia or atypical lobular hyperplasia. At a mean follow-up of 4.8 years, there have been no new breast malignant neoplasms in these 45 women.

[CONCLUSIONS] The occurrence of unilateral cancer in patients with family history of breast cancer is associated with a 15.4% probability of simultaneous occult malignant neoplasms in the contralateral breast. Patients with a strong family history but no evidence of breast cancer have a substantially similar rate of proliferative disease in their PM specimens as those women who have unilateral cancer but no significant family history.