Multi-gene hereditary cancer testing among men with breast cancer.

Abstract

1532 Background: All men with a personal diagnosis of breast cancer (BC) are candidates for BRCA1/2 genetic testing, as pathogenic variants (PVs) in these genes have a known association with BC risk in both men and women. As additional genes with known BC risk in women are now routinely included in multi-gene panel testing, we evaluated the outcomes of multi-gene panel testing in a large cohort of men with BC. Methods: This analysis includes the results of commercial genetic testing for 1,358 men with BC usinga multi-gene pan-cancer panel between September 2013 and January 2017. Clinical information was obtained from provider-completed test request forms. Age at diagnosis, personal, and family history were compared for men with PVs in BRCA1/2 versus non- BRCA1/2 genes. Results: Overall, 207 (15.2%) men with BC were found to carry a PV, where 147 (10.8%) men had a PV in BRCA1/2 ( BRCA1, 0.7%; BRCA2, 10.2%) and 60 (4.4%) men had a PV in a non- BRCA1/2 gene ( CHEK2, 2.0%; ATM, 1.0%; PALB2, 1.0%; BARD1, 0.2%; NBN, 0.2%; MSH6, 0.1%; BRIP1, 0.1%; CDH1, 0.1%; CDKN2A, 0.1%; MLH1, 0.1%, TP53, 0.1%). There were no substantial differences in the median age-at-diagnosis for men without a PV (65) compared to those with a BRCA1/2 PV (66) or a non- BRCA1/2 PV (63). Prostate cancer was the most common additional malignancy among all men with BC (9.0%), with a similar incidence among men with a BRCA1/2 PV (9.2%) and a non- BRCA1/2 PV (8.3%). In addition, 1.4% of men with a BRCA1/2 PV and 3.3% of men with a non- BRCA1/2 PV had a second BC. A family history of breast and/or ovarian cancer was present in 44.4% of the testing cohort, 66.7% of men with a BRCA1/2 PV, and 48.3% of men with a non- BRCA1/2 PV. This is consistent with the relative penetrance of BRCA1/2 and other genes included here. There were no other substantial differences in family history among BRCA1/2 PV carriers versus non- BRCA1/2 PV carriers. Conclusions: Close to a third of all PVs identified here in men with BC were in a gene other than BRCA1/2. There were no obvious differences in the clinical presentation of men with a BRCA1/2 PV compared to men with a PV in another gene or no PV at all. Collectively, this suggests that multi-gene panel testing is appropriate for all men with BC, regardless of other personal or family history.