In order to examine the relationship between BRCA1 promoter methylation, BRCA1 protein expression, triple negativity and BRCA1 associated histopathological features we have analysed blood samples from 658 women with sporadic breast cancer and 170 matched tumour samples; 71 (11%) and 35 (21%) of these samples were classified as TN respectively. Here, BRCA1 is linked to breast cancer.