Background: Currently, genetic testing is recommended to those patients diagnosed with breast cancer at a young age, with triple negative disease, Ashkenazi ancestry and/or a significant family history of breast, ovarian, prostate or pancreatic cancer. This precludes the opportunity to apply precision medicine approaches to women who do not meet these criteria. Timing and uptake of testing in high-risk patients and frequency of mutation detection in low-risk patients was evaluated in a cohort of women with invasive breast cancer treated at the Murtha Cancer Center of the Walter Reed National Military Medical Center (MCC/WRNMMC), the largest hospital of the Department of Defense health-care system.

Methods: 1,231 women enrolled in the Clinical Breast Care Project of the MCC/WRNMMC 2001-2018 with invasive breast cancer. Genetic risk status was estimated using NCCN BRCA1/2 Testing Criteria. Panel testing was performed in the research laboratory for 1,043 women who had genomic (blood) DNA available. Genetic variants across 94 cancer predisposition genes were classified as pathogenic, variant of unknown significance (VUS) or benign using the ClinVar database.

Results: Using NCCN version 1.2018 criteria, 57.8% of patients were eligible for genetic testing. Uptake of testing within the high-risk group was 40.0%; those who pursued genetic testing were significantly (p<0.001) younger and more likely to be college educated. Time-to-testing ranged from 0 to 15.3 years post-diagnosis and 6.3% of women pursued clinical testing only after a second tumor event. 19.3% of the high-risk women with clinical testing, 7.5% of high-risk women who did not pursue clinical testing and 4.4% of low-risk women carried a pathogenic or likely pathogenic mutation.

Conclusions: More than 4% of breast cancer patients who chose not to pursue or were ineligible for genetic testing harbored pathogenic mutations in cancer predisposition genes. These data suggest that inclusion of panel testing at the time of diagnosis would allow for appropriate surveillance and treatment strategies to be employed to reduce the risk of secondary tumors and improve patient outcome. The contents of this publication are the sole responsibility of the author(s) and do not necessarily reflect the views, opinions or policies of Uniformed Services University of the Health Sciences (USUHS), The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., the Department of Defense (DoD), the Departments of the Army, Navy, or Air Force. Mention of trade names, commercial products, or organizations does not imply endorsement by the U.S. Government.

Citation Format: Seth Rummel, Leann Lovejoy, Clesson Turner, Craig Shriver, Rachel Ellsworth. Should genetic testing for cancer predisposition be standard-of-care for women with invasive breast cancer: The Murtha Cancer Center experience [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4624.