Urgent cancer genetic counseling and testing for young, premenopausal women with breast cancer (BC): Impact on surgical decision-making for contralateral risk-reducing mastectomy.

Abstract

1533 Background: In women newly diagnosed with unilateral breast cancer (BC), contralateral risk-reducing mastectomy (CRRM) to decrease risk for additional primary BC is an appropriate option for some individuals, such as those with significantly increased risk due to a pathogenic variant (PV) in a breast cancer predisposition gene. Genetic testing at the time of BC diagnosis for young women has become more available and could aid in the decision-making process. We evaluated the trends for CRRM in a cohort of women diagnosed with BC at age ≤45 years who were seen in a multidisciplinary clinic where genetic counseling and testing is offered to each patient. Methods: A single institution, prospectively maintained database of patients seen in a BC multidisciplinary clinic between November 2014 and June 2019 was reviewed. Patients were included if they had non-metastatic, unilateral BC diagnosed ≤45 years of age, and underwent genetic testing at the time of BC diagnosis. Associations between surgical treatment (lumpectomy, mastectomy, or mastectomy with CRRM) and age at diagnosis, BC stage, family history, and genetic testing results were evaluated. Results: 184 patients were included in the analysis. The prevalence of a PV in a breast cancer predisposition gene was 15.8% (29/184; 1 in ATM, 12 in BRCA1, 8 in BRCA2, 5 in CH EK2, 2 in NBN, and 1 in NF1). 69% of the PV were in BRCA1 and BRCA2. 126 (68.4%) tested negative, and 29 (15.8%) had a variant of uncertain significance (VUS) in various genes. Overall, 63 patients (34.2%) elected to have CRRM. Of the 29 patients with a PV, 24 (82.8%) had CRRM. Women who chose CRRM were younger, more likely to test positive for a PV in a breast cancer predisposition gene, and more likely to have a significant family history of breast and/or ovarian cancer. Among the 155 patients who tested negative or had a VUS, there was no statistically significant association between CRRM and age (p = 0.58), test result (negative vs. VUS. p = 0.12), or family history (p = 0.32). Conclusions: For young women with BC seen in a multidisciplinary clinic, a younger age, significant family history, and positive genetic testing result were found to be associated with the decision to undergo CRRM. Among those without a genetic predisposition, having a VUS result was not associated with choosing CRRM. Incorporation of genetic services in the initial evaluation of young patients newly diagnosed with BC could add relevant information in surgical decision making and promote risk-appropriate management.