These approaches include (1) comprehensive testing for germline pathogenic variants in BRCA1/2 genes; (2) analysis of gene-inactivating germline variations in other members of the HR pathway; (3) identification of tumor-specific somatic mutations in BRCA1/2 and similar genes; (4) complex assays aimed at the detection of chromosomal instability in tumor cells; (5) functional HRD assays; (6) analysis of the clinical course of cancer disease, i.e., platinum sensitivity of the tumor. This evidence concerns the gene BRCA1 and cancer.