BRCA1/2 Variants Identified Through Tumor Genomic Profiling: Assessing Genetic Counseling Outcomes.

Abstract

As tumor genomic profiling (TGP) is increasingly used to help guide cancer treatment, BRCA variants, which may or may not be reflective of the germline genome, are being identified. As TGP use increases, it is becoming an important tool for referral to genetic counseling and identifying patients with hereditary cancer syndromes such as hereditary breast and ovarian cancer. This study explores genetic counseling referral patterns and germline implications of patients found to have pathogenic BRCA1/2 variants identified through TGP. Participants include patients at Huntsman Cancer Institute undergoing TGP through a single commercial laboratory between March 2014 and July 2018. A retrospective chart review was conducted for 62 patients found to have pathogenic variants (PVs) in BRCA1/2 on TGP. Data on genetic counseling referrals and uptake, germline test results, family history, and patient demographics were collected. In the study time frame, 1,899 patients underwent TGP. Testing identified 67 PVs in BRCA1 (23 variants) or BRCA2 (44 variants) in 62 patients. Thirty-five patients first received a referral to a genetic counselor following TGP with 33 patients completing genetic counseling. Of the 30 patients who pursued germline genetic testing following TGP, 11 were discovered to have a previously unknown germline BRCA PV. Nine of these patients were the first in their family diagnosed with hereditary breast and ovarian cancer. This study represents one institution's experience with genetic counseling referrals, uptake, and germline results following TGP. For some patients, TGP will be the first indicator of an underlying hereditary condition. Identifying patients with PVs (which may be germline) through TGP is an important new genetic counseling referral tool that can have important implications for the patient and their family.