Aim: To survey the histopathological abnormalities in breasts of women who have undergone risk reducing mastectomy and to evaluate the effect of this measure on future breast cancer development.
Patients/methods: Between August 1995 and October 2006 100 consecutive women with a hereditary increased risk of breast cancer underwent prophylactic mastectomy (PM) at Malmö University Hospital. Fifty of the 100 women had no previous breast cancer. Fifty were BRCA1 or BRCA2 mutation carriers. All breast specimens have been examined histopathologically according to a prospective protocol. Follow-up data was collected from medical records and data in the Regional Cancer Registry.
Results: In the PM specimens abnormal lesions were found in 18 women (three with invasive cancers, eight in situ cancers and seven atypical hyperplasia). In previously healthy women lesions were more frequent after the age of 40 than among younger women (p=0.03). BRCA mutation carriers were more likely to present with ADH (atypical ductal hyperplasia)/ALH (atypical lobular hyperplasia) compared to the non-carriers/untested cases (p=0.01). After a median follow-up of 52 months (range 1-136 months) none of the women have developed breast cancer in the area of the prophylactically removed breast.
Conclusions: Prevalent atypical or malignant lesions are relatively a common finding in PM specimens in asymptomatic women with hereditary increased risk of breast cancer. Such findings were significantly more common above age 40 in women without previous breast cancer. The risk of newly formed breast cancer after PM is small. The clinical importance of detecting a premalignant or preinvasive lesion in the breast at PM is still unclear.