Abstract P6-08-28: Comprehensive germline multigene panel testing changes clinical care for patients with breast cancer

Background: HBOC testing guidelines were established to identify patients with clinically actionable variants and limit economic burden. We report the impact of germline results on health outcome based on clinical decision making and treatment interventions, regardless of guidelines, in a multi-center registry. Methods: 20 community-based and academic sites participated in an IRB approved registry. Patients with breast cancer were tested with an 80-gene panel and clinical information was collected. Results: Data on 912 patients has been analyzed to date. 68% were recently diagnosed and the remaining were diagnosed in the past. 50.5% met NCCN criteria; 49.5% did not. Pathogenic/likely pathogenic (P/LP) germline mutations were found in 8.65% of patients. Of all patients with P/LP findings, 85% had variants in cancer-risk genes with established management recommendations and 80% had germline variants conferring eligibility for clinical trials and precision medicine-based cancer treatments, such as PARP inhibitors. When results were evaluated based on an 11 gene panel of genes most commonly associated with breast cancer, 4.9% (or X) were found to have variants and X percent of these had variants conferring eligibility for clinical trials and precision medicine. X Patients with variants outside of the 11 gene panel had eligibility for clinical trials and precision medicine. There was no significant association between BRCAPRO scores and patients having a P/LP finding, whether in BRCA1/2 alone (p=0.42) or for any cancer gene (p=0.57). For 62% of patients with P/LP germline mutations, clinicians reported results impacted patients’ health outcome; and for 69%, results impacted the health outcome of patients’ relatives. Physician reported impact on patient outcome associated significantly with the presence of P/LP germline findings (p Conclusions: Comprehensive panel testing of breast cancer patients impacts physician assessed patient outcomes and informs changes in surgical treatment strategy, medical therapies and proactive screening. The data suggest that BRCAPRO calculators are poor predictors of germline presence of P/LP findings. Physicians in this study demonstrate the ability to discern the clinically actionable value of P/LP mutations from non-actionable VUS. Multigene panels impact breast cancer patient care by identifying precision medicine treatment interventions and guiding long-term medical management and preventive surveillance for patients and family members. More patients are provided opportunities for precision medicine when a larger panel is used. Citation Format: Peter Beitsch, Pat Whitworth, Kevin Hughes, Ian Grady, Karen Barbosa, Rakesh Patel, Michael Kinney, Paul Baron, Barry Rosen, Gia Compagnoni, Linda ann Smith, Rache Simmons, Cynara Coomer, Dennis Holmes, Eric Brown, Linsey Gold, Lisa Curcio, Patricia Clark, Tony Ruiz, Heather MacDonald, Sadia Khan, Lee Riley, Sam Lyons, Shan Yang, Mary K Hardwick, Edward D Esplin, Robert L Nussbaum. Comprehensive germline multigene panel testing changes clinical care for patients with breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-08-28.