BRCA1 and breast cancer: The use of HRD-associated mutational signatures to predict “BRCAness” and thus response to PARP inhibitors and platinum chemotherapy has received significant attention in recent years, with tools such as HRDetect19 and CHORD38 demonstrating that HRD-associated mutational signatures can be used to predict BRCA1/BRCA2-deficiency in breast tumours as well as survival of breast cancer patients39.