In addition to sensitizing cancer cells to traditional radiation- and chemotherapies, RAD51 inhibitors (RAD51i) may also render tumors proficient in HR, responsive to inhibitors of poly (ADP ribose) polymerase (PARPi) that generally target HR-deficient cancers, e.g., cancers carrying mutated BRCA1/2 genes [29]. This evidence concerns the gene BRCA1 and cancer.