Comprehensive germline panel testing across cancer types: Diagnostic yield and clinical utility in 100,000 patient dataset.

Abstract

e13013 Background: Over 608,000 patients with ovarian, breast, pancreatic, prostate and colorectal cancer are diagnosed each year. NCCN guidelines recommend offering germline genetic testing to all patients with ovarian and pancreatic cancer, and patients with prostate and breast cancer who meet specific criteria. We present data from ~113,000 patients who were tested on a comprehensive multigene panel and compare the diagnostic yield and clinical actionability with that of a limited gene panel strategy. Methods: We analyzed de-identified sequence data for 83 cancer-risk genes in patients with breast, ovarian, prostate and pancreatic cancer referred for germline genetic testing. Positive rates for a minimal gene panel for the respective indication were computed and compared to the positive rates when the comprehensive 83 gene panel was analyzed. Results: Four percent of 103,428 patients with breast, ovarian, pancreatic and prostate cancer harbored a BRCA1 or BRCA2 germline mutation including: breast 3.7%, ovarian 8.2%, prostate 5.2% and pancreatic 4.2%. When the comprehensive panel is applied, the overall diagnostic yield for all 113,107 patients increased to 16%. Excluding mono-allelic P/LP variants in recessive cancer-risk genes (e.g. MUTYH) reduces the diagnostic yield to 13%. Stratified by cancer type, and removing mono-allelic recessives, positive yield was: breast 11.8%, ovarian 18%, prostate 15%, and pancreatic 16%. Conclusions: These data show that comprehensive panel testing in patients with a broad range of cancers more than doubles the diagnostic yield, providing actionable results for an additional 9,737 per 113,107 patients tested. Potential germline-based clinical actionability for these patients includes: 1) pan-cancer eligibility for PARP inhibitor clinical trials, 2) FDA approved PD1 blockade for advanced cancer of ANY type and a molecular diagnosis of Lynch syndrome, 3) cascade family variant testing.This study suggests that genetic testing guidelines should be expanded to include recommendations supporting multigene panel testing in patients with cancer to improve the care of patients and their family members.