Utility of Expedited Hereditary Cancer Testing in the Surgical Management of Patients with a New Breast Cancer Diagnosis.

BACKGROUND: Knowledge of a germline pathogenic/likely pathogenic variant (PV) may inform breast cancer management. BRCA1/2 PV often impact surgical decisions, but data for multi-gene panel testing are lacking. Expedited genetic testing reduces turn-around times based on request for treatment-related decision making. This report aims to describe the clinical utility of expedited multi-gene panel testing for patients with newly diagnosed breast cancer.

METHODS: Clinical and demographic information were reviewed for patients with newly diagnosed female breast cancer undergoing expedited panel testing between 2013 and 2017. The National Comprehensive Cancer Network guidelines (NCCN, version 1.2018) were evaluated in terms of published management recommendations for the genes in which PVs were identified.

RESULTS: The overall PV yield was 9.5% (678/7127) for women undergoing expedited panel testing, with 700 PVs identified among 678 women. PVs were identified in genes other than BRCA1/2 in 55.9% (391/700) of cases. The NCCN guidelines recommend management for the genes in which 96.6% (676/700) of PVs are identified. The NCCN guidelines also recommend risk-reducing mastectomy for 46.0% (322/700) of PVs identified. An additional 45.6% (319/700) of PVs were identified in genes for which NCCN recommends mastectomy based on family history. In addition, 49.9% (349/700) of PVs were in genes with NCCN guidelines recommending prophylactic surgery for tissues other than breast.

CONCLUSION: A majority of the patients with newly diagnosed breast cancer were candidates for surgical intervention according to the NCCN guidelines, and half of these patients would have been missed if only BRCA1/2 testing had been ordered. Expedited multi-gene hereditary cancer panel testing should be considered as a first-line approach to provide comprehensive information for breast cancer management.