Outcomes of retesting BRCA-negative patients using multigene panels.

Abstract

23 Background: New technologies for identifying hereditary predisposition to breast cancer have led to the discovery of novel genes associated with cancer risk. This has prompted re-evaluation of patients who previously tested negative for BRCA1/2 gene mutations, with a possibility of discovering new genes which may impact management. This study reports on the results of retesting patients who previously were negative for BRCA1/2. Methods: Patients who tested negative for BRCA1/2 mutations who had significant personal and family history were referred back to the Cancer Genetics Center between February 1, 2012 and May 30, 2105 for discussion of additional testing. A detailed personal and family history was reviewed, and patients were counseled about the genetics and clinical implications of panel testing for multiple breast cancer genes. Panel testing using next generation sequencing technologies was ordered. Patients were seen in follow up for discussion of results and management. Results: A total of 12 pathogenic mutations were identified during the study period. The genes and frequencies of these mutations were: CHEK2(3), PALB2(3), ATM(2), APC(1), BARD(1), CDH(1), MUTYH(1). There were 33 variants of undetermined significance(VUS) in 27 patients. 5 of these were seen in patients with a known pathogenic mutation; 3 others were later classified as benign. The frequencies of these VUSs were: ATM (9), PALB2(3), BARD1 (3), PTEN(3), PMS2(3), MSH6(2), CHEK2 (1), MYH(1), RAD51(1), BRIP1(2), NF1(1), BMPR1A(1). Of the 46 patients who had their initial BRCA testing and repeat panel testing between February 1, 2012 and May 30, 2015, 6 (13%) tested positive for a pathogenic mutation. Conclusions: This study demonstrates the feasibility and potential clinical benefit of retesting individuals who previously tested negative for BRCA1/2 mutation. This approach had a significant management impact on patients and their families, with a 13% detection rate of pathogenic mutations. The success of retesting is predicated upon an infrastructure of provider and patient education, pre and post genetic counseling and serves as a model for other centers.