Prevalence of germline pathogenic variants in 779 patients with metastatic prostate cancer.

To assess the prevalence of germline pathogenic variants (gPVs) in genes associated with female breast cancer in Dutch patients with metastatic prostate cancer (mPCa). In this prospective multicentre cohort study (n = 15 centres), germline genetic testing of the genes BRCA1, BRCA2, ATM, CHEK2 and PALB2 was offered to patients with mPCa. We assessed the prevalence of gPVs and compared it to a reference population of 16 823 individuals who underwent genetic testing for non-oncological conditions. Additionally, we identified factors that increased the likelihood of carrying a gPV. A total of 779 patients with mPCa underwent germline genetic testing, of whom 46 (5.9%) had a gPV in a DNA damage repair gene. Most gPVs were found in CHEK2 (1100delC variant), ATM and BRCA2, all significantly more prevalent than in the reference population (odds ratios 2.4, 2.8 and 3.1, respectively). The prevalence of gPVs in BRCA1 and PALB2 was not significantly increased. Patients with a second primary cancer, a first- or second-degree relative with breast cancer at age < 50 years, or pancreatic cancer, or Jewish ancestry had the highest likelihood of carrying a gPV. We found that gPVs in CHEK2, ATM and BRCA2 were associated with men presenting with mPCa. Several factors increased the likelihood of carrying such a variant and, in these cases, healthcare professionals should be aware of the need to offer germline genetic testing.