Unfortunately, most current circulating breast cancer markers, including serum tumour markers (CA15-3, CA27.29, CEA), circulating cancer DNA or cell-free DNA (mutation of TP53, KRAS, PIK3CA and promoter methylation of APC, BRCA1, TWIST) and circulating tumour cells (CTCs), exhibit low sensitivity24–26. The gene discussed is BRCA1; the disease is neoplasm.