Germline testing in community oncology patients with somatic BRCA1/2 mutations.

Abstract

1523 Background: The primary purpose of tumor mutation profiling (TMP) is to molecularly characterize tumors to identify targeted treatments and improve outcomes, but it may also uncover germline mutations with implications for patients and families. In September 2016, the National Comprehensive Cancer Network (NCCN) added “BRCA1/2 mutation detected by TMP” as a criterion for germline BRCA1/2 testing. This study aims to assess rates of germline testing, with and without genetic consultations, for individuals with a somatic BRCA1/2 finding in community oncology centers. Methods: Retrospective data was abstracted from an internal database of results from four TMP laboratories. Individuals with a somatic BRCA1/2 pathogenic/likely pathogenic (P/LP) variant reported from January 1, 2017 to December 31, 2019 were included. Clinical data was obtained from electronic medical records. The project was approved by the Texas Oncology Privacy Board. Results: 221 patients had a P/LP somatic BRCA1/2 result on TMP, 138 of which were BRCA1/2 spectrum tumors (breast, ovary, pancreas, prostate). 144/221 patients (65.2%) had BRCA1/2 germline testing. 133/221 (60.2%) met NCCN guidelines for germline BRCA1/2 testing independent of their somatic results; they were statistically more likely to undergo germline testing than patients who did not otherwise meet germline BRCA1/2 testing criteria (p=2.3e-16) (Table). 70/144 (48.6%) had a germline P/LP BRCA1/2 mutation identified. At locations with genetic providers versus those without, there was a significant difference in rates of genetic consultation (p=0.02) but not in the rate of germline testing (p=0.3). This indicates patients were more likely to receive pre- and post-test counseling at clinics offering in-house genetic consultations. Conclusions: Most individuals who had a P/LP somatic BRCA1/2 mutation identified on TMP underwent germline genetic testing. As 60.2% of our cohort qualified independently for germline testing, somatic BRCA1/2results may not have been the driving force behind germline testing. However, individuals who had a non- BRCA1/2-spectrum tumor were significantly less likely to have the recommended confirmatory germline testing. Quality improvement initiatives can focus on improving rates of counseling and germline testing for patients with somatic BRCA1/2 mutations, regardless of tumor type.[Table: see text]