Abstract P5-13-03: Factors associated with prophylactic mastectomy among BRCA-positive patients with no personal history of breast cancer

Abstract

Background: The rate of prophylactic mastectomy (PM) has recently increased1. A deleterious mutation in the BRCA1 or BRCA 2 genes is among the major reasons why patients pursue PM 2, 3. Women with BRCA1 or BRCA2 gene mutations have up to an 87% risk to develop an invasive breast cancer (BC), and up to 45% risk for ovarian cancer (OC)2, 3. Most studies evaluating predictors of PM in BRCA mutation carriers are performed among women with breast cancer; however, accurate predictors for PM among unaffected BRCA mutation carriers are less defined. In a single institution study we aimed to evaluate predictors of PM among BRCA carriers with no personal history of breast cancer. Method: One hundred seventy seven women with no personal history of BC, who tested positive for a BRCA1 or BRCA 2 germline mutation, were included in the study. Patients’ characteristics were obtained from a prospectively maintained research database under an IRB approved protocol at UT MD Anderson Cancer Center. Univariate analyses using chi-square and logistic regression analysis were used to determine predictive factors associated with PM. The patient characteristics examined included age, martial and educational status, bilateral salphingo-oophorectomy (BSO), family history of 1st and 2nd degree relatives with breast (BC) and ovarian cancer (OC), race, and BRCA genetic test result. Results: Out of the 177 BRCA1 and BRCA 2 positive patients, 51 (29%) elected for PM. The average age for the cohort was 44 years (range 23-91). The majority were Caucasian (81%), and married (72%) with a college degree (64%). One hundred sixty-four (92%) patients had 1st and 2nd degree relatives with BC, 93 (53%) had 1st and 2nd degree relatives with OC, and 85 (48%) had undergone BSO. A logistic regression model was run to identify factors associated with undergoing PM, including family history of OC, family history of BC, BSO and age. Patients with a family history of OC were 2.5 times more likely than those without to have had a PM (p = 0.0125), and patients who had a BSO were 0.137 times less likely to have had a PM (p <.0001). Only 12 patients did not have a family history of BC and none of those patients had a PM, so an Odds Ratio could not be calculated. However, it was determined through the Fisher's exact test that patients with a family history of BC were more likely to undergo a PM (p = 0.0198). Conclusion: The rate of PM in our cohort was slightly lower than expected. Factors associated with PM included a family history of BC and OC. Interestingly, having had a BSO was associated with lower likelihood of undergoing PM (menopausal status will be further evaluated); possibly due to the knowledge that BSO reduces breast cancer risk. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-13-03.