Mainstream Germline Genetic Testing with Expanded Eligibility for Early Breast Cancer Patients in a Large Integrated Health System

Background: This study evaluated a new mainstream genetic testing pathway for hereditary cancer, with expanded eligibility for early-stage breast cancer patients.

Methods: The study compared multigene panel (62 genes) germline testing uptake and results for breast cancer patients at 4 pilot sites (n = 502 patients) and 10 non-pilot sites (n = 1792 patients) within Kaiser Permanente Northern California from December 2020, to June 2021. At the pilot sites, breast care coordinators (BCCs) offered and consented patients for testing, with eligibility expanded to include all patients age 65 years or younger. At the non-pilot sites, eligible patients were referred to genetics for pre-test counseling, ordering, and follow-up evaluation with the standard guideline that included all patients age 45 years or younger.

Results: Demographic and disease characteristics were similar at the pilot and non-pilot sites. At the pilot verses non-pilot sites, a higher percentage of patients was tested overall (61.6% vs 31.7%) and across all age groups. The median time from breast biopsy to test result also was reduced (22 vs 33 days, respectively). A higher percentage of patients at the pilot sites was identified as having a pathogenic/likely pathogenic variant (PV/LPV) in a breast cancer-related gene (3.6% vs 1.6%). Although the percentage of total patients tested was nearly twofold higher at the pilot sites than at the non-pilot sites, the percentage of total patients seen by genetics was estimated to be similar (33.7% vs 31.7%).

Conclusion: Mainstream genetic testing of breast cancer patients facilitated by BCCs makes it feasible for a large health care system to expand germline genetic testing to early breast cancer patients age 65 years or younger.