Germline analysis of DNA-damage repair genes in men with advanced prostate cancer in comparison to women with breast cancer.

Abstract

e13147 Background: Women with breast cancer have traditionally been the population for genetic counseling. The association of hereditary cancer syndromes and the development of advanced prostate cancer have been established only since recent years. There has been increased utilization of germline analysis in men with prostate cancer since NCCN updated its guideline on genetic testing for DNA damage repair (DDR) genes in the homologous recombination (HR) pathway in this population. In this study, we analyzed the prevalence of genetic alterations in DDR genes in men with advanced prostate cancer in relevance to women with breast cancer in our institution. Methods: Patients who were referred to genetic counseling in 2018 and met NCCN criteria underwent genetic testing following pretest genetic counseling. Samples obtained from buccal mucosa or peripheral blood were analyzed for germline variants using commercially available multi-gene panels which included DDR genes in the HR pathway. Results: In 2018, 54 men with prostate cancer with relapsed disease following local therapy, or de novo metastasis, and 305 women with breast cancer were included. At least one pathogenic or likely pathogenic variant was identified in 9 men (16.7%), most frequently in BRCA2, ATM, and CHEK2, as compared to those in 30 women (9.8%), p = 0.137. 17 men (31.5%) had at least one variant of uncertain clinical significance (VUS) detected in a DDR gene as compared to those in 74 (24.3%) women with breast cancer, p = 0.261. Conclusions: Men with advanced prostate cancer have a statistically comparable but numerically trending higher frequency of pathogenic variants and VUS in DDR genes detected on germline testing in comparison to women with breast cancer. The high prevalence of VUS in prostate cancer is an intriguing finding. VUS represent a genetic alteration with undefined clinical outcome. With increasing genetic testing in prostate cancer, further correlation between VUS of DDR genes and clinical risk features from a larger population is warranted.