BRCA1 and ovarian cancer: Mutations can either be germline (inherited) or somatic (acquired) and initial clinical trials of PARP inhibitors were conducted in ovarian cancer patients with germline BRCA mutations; however, subsequent studies suggested that somatic mutations in HRR genes, including BRCA1 and BRCA2, had a similar biological phenotype to germline mutated tumours and these patients had also been shown to benefit from treatment with PARP inhibitors [5–7].