While other cancer cohorts — biliary, colorectal, non-small cell lung cancer, sarcoma, and cancers of unknown primary (tumors of unknown origin) — had a lower prevalence of BRCA1/2 alterations, previous work has suggested that these cohorts may exhibit the HRD phenotype and respond to PARP inhibitors (Fig. 1B) [66–68]. This evidence concerns the gene PARP1 and cancer.