Timing and uptake of germline testing in patients with somatic BRCA1/2 pathogenic or likely pathogenic variants in solid tumors: A real-world study from community oncology practices.

576 Background: Inherited or germline BRCA mutations are found in about 1 in 400 people around the world and carry significant implications for cancer risk, therapeutic and preventive strategies. When somatic BRCA1/2 pathogenic or likely pathogenic variants are detected, guidelines recommend confirmatory germline testing due to implications for targeted treatment, family counseling, and cancer risk management. Nonetheless, evidence suggests that germline testing is underutilized in practice, even among patients meeting testing guidelines. Methods: This retrospective observational cohort study used electronic health record data from 11 practices in The US Oncology Network participating in the Genetic Risk Evaluation and Testing program to examine patterns of germline testing. Patients with somatic pathogenic or likely pathogenic variants in BRCA1 or BRCA2 genes in solid tumors identified between 1 November 2021 and 1 November 2023 were included in the study. Patients were followed through 1 April 2024. The timing of germline testing (date of test order) relative to the date of somatic testing result was determined. Results: Among 526 patients identified with somatic BRCA1/2 mutations across 15 solid tumor cancer types, 289 (55%) also had germline testing. For most cancers, germline testing preceded somatic testing. These were generally cancers associated with hereditary BRCA mutation, including breast, ovarian, other gynecological cancers, and prostate cancer. Cancers for which germline testing was observed to be done after the somatic test results included non-small cell lung cancer, bladder, and esophageal cancers. Conclusions: Germline testing for BRCA1/2 is not performed consistently, particularly in cancers not traditionally linked to hereditary syndromes. Overall, almost half of patients with a known somatic BRCA mutation did not receive germline testing. This testing gap represents a missed opportunity for personalized therapy and familial risk assessment. Enhancing awareness and adherence to genetic testing guidelines in community oncology can improve cancer prevention, treatment decision-making, and care equity. Germline testing patterns for select solid tumor types in patients with pathogenic or likely pathogenic variants BRCA1 or BRCA2 mutation on somatic profiling. Overall (N=526) Breast Cancer (n=102) Ovarian Cancer (n=71) Non Small Cell Lung Cancer (n=71) Colon Cancer (n=51) Prostate Cancer (n=35) Bladder Cancer (n=19) Esophageal Cancer (n=18) Patients with a germline test, n (%) 289 (54.94%) 72 (70.59%) 61 (85.92%) 14 (19.72%) 21 (41.18%) 24 (68.57%) 8 (42.11%) 4(22.22%) Median days between germline test order and documented somatic test result* -74 -585 -221 16 -27 -14 19 10