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.

Differences in cancer prevalence among CHEK2 carriers identified via multi-gene panel testing.

PURPOSE: Although CHEK2 is a well-established cancer gene, questions remain including whether risks vary substantially between different variants and whether biallelic carriers have higher risks than heterozygotes. We report on a cohort of individuals with CHEK2 pathogenic and likely pathogenic variants (collectively, PV) in order to better characterize this gene. METHODS: We retrospectively queried samples submitted for multi-gene hereditary cancer testing to identify individuals with CHEK2 PVs and assessed differences in phenotypes among various genotypes. RESULTS: CHEK2 PVs were identified in 2508 individuals, including 32 individuals with biallelic CHEK2 PVs. Breast (female, 59.9% and male, 11.8%), prostate (20.1%), and colorectal (3.5%), were among the most frequently reported cancers. Select missense PVs showed similar cancer prevalence to truncating PVs while some others showed lower prevalence. No significant differences were observed between biallelic carriers and heterozygotes. CONCLUSIONS: Our data support that some, but not all, CHEK2 missense PVs demonstrate lower cancer prevalence; further studies are needed to continue characterizing possible variant specific risks. In addition, biallelic CHEK2 PVs do not appear to be associated with a more severe phenotype than single CHEK2 PVs. Furthermore, co-occurrences with PVs in other cancer risk genes are common among CHEK2 heterozygotes and often warrant additional management.