Both cancers are also associated with pathogenic variants in male BC susceptibility genes: prostate cancer with the BRCA1/2 [35, 36, 46] and CHEK2 [47–49] genes and stomach cancer with the BRCA1/2 [35, 36, 50] and CHEK2 [51] genes. This evidence concerns the gene BRCA1 and Familial prostate cancer.