Inherited pathologic mutations and family history in patients with prostate cancer.

Abstract

185 Background: In prostate cancer (PCa), germline pathogenic variants have previously been underestimated. PCa patients (pts) with DNA repair defects have a higher percentage of non-PCa family history (FH) with the most common cancers being derived from the breast, GI tract, ovary, pancreas, lymphoma/leukemia. The goal of this study was to evaluate and characterize pathogenic variants detected in PCa patients undergoing both enhanced FH screening and genetic testing. Methods: In this single-institution study, 535 PCa pts from Tulane Cancer Center over the last year underwent enhanced FH screening, and FH of PCa and other cancers were collected. 124 PCa pts including those with both localized and metastatic disease were identified to have a FH that met NCCN guidelines for genetic testing. Genetic testing was done using a commercially available panel (Invitae, San Francisco, CA) of 25-79 cancer-related genes for mutations and selected exonic deletions/duplications. Results: Of the 124 tested pts, 21 pts (16.9%) had ≥ 1 germline pathogenic variant (PV) and 47 pts (37.9%) had ≥ 1 germline variant of unknown significance (VUS). PVs included: BRCA2 (n = 4), BRCA1 (n = 3), CHEK2 (n = 3), MUTYH (n = 3), ATM (n = 2), TP53 (n = 2), MITF (n = 1), NBN (n = 1), PMS2 (n = 1), and (RAD51D (n = 1). Of the 124 tested pts, 68 pts (54.8%) had PCa FH, 68 (54.8%) had breast cancer FH, 22 (17.7%) had pancreatic cancer FH, 16 (12.9%) had ovarian cancer FH, and 37 (29.8%) had both breast and PCa FH. Between the pt groups (those with PVs, VUSs and negative results), there were no differences in FH rates of PCa, breast, pancreatic, or ovarian cancer. There was no significant difference in the age at diagnosis (dx) between the groups or between pts with PCa FH and those without. The median ages at dx were 65 for PV pts, 60 for VUS pts, and 59 for negative result pts. There were no statistically significant differences in initial Gleason score or metastatic disease status in these three groups (p = 0.35 and p = 0.66). Conclusions: In this dataset, FH cannot discriminate between those with and without inherited PV using a broad panel of genes that include those that alter DNA repair. The implications of these findings are broad. [Table: see text]