Huntsman Cancer Institute at the University of Utah, Salt Lake City, UT
Samantha Greenberg , Brock O'Neil , Kathleen A. Cooney , Lisa M. Pappas , Jonathan David Tward
Background: Growing evidence suggests up to 12% of men with metastatic prostate cancer (PC) harbor a pathogenic variant (PV) in genes associated with hereditary cancer risk. Updated NCCN PC guidelines include consideration for germline testing (GT) in men with high risk, very high risk, regional, or metastatic PC. As a result, we expanded our criteria for GT in men with PC to include these groups and men with a strong family history for PC beginning in January 2018. This study reports the clinical characteristics and germline findings before and after this expansion. Methods: Men with PC underwent multi-gene genetic testing (GT) for PVs from June 2016-June 2018 with genetic counselors. Clinical information and germline GT results were analyzed. Results: Of 285 eligible men who met with a genetic counselor, there were 201 evaluable GT results. One PV was excluded for suspicion of clonal hematopoiesis of indeterminate potential. Twenty-seven PVs were identified in 24 men (12.4%). Three men had two PVs identified (1.5%), at least one PV of which was in ATM or BRCA2. The most common PVs were ATM (n = 6, 3.0%), BRCA2 (n = 7, 3.5%), MYH (n = 4, 2.0%), and HOXB13 (n = 4, 2.0%). Rate of PVs were not statistically different across the two timeframes of GT, (2016-17, 14%; 2018, 11.2%; p = 0.60). PVs were not statistically associated with a higher ISUP group (1-3: 10.1%, 4-5: 13.6%; p = 0.49) and were distributed across multiple NCCN risk groups. Almost all men tested reported a family history of cancer, with the most frequent cancers reported including PC (n = 79, 39.3%), breast (n = 55, 27.4%), and colon cancer (n = 23, 11.4%). Family history of PC was not statistically associated with genetic test results (PV: 54%, no PV: 37%; p = 0.11). Conclusions: Expanding germline GT criteria will substantially increase patient volume without significant changes to the PV rate. Higher PC risk defined by ISUP or NCCN was not associated with the rate of PVs. Given this finding, further broadening the criteria for GT in PC may be warranted.
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