Interestingly, high BARD1 and BRCA1 expression was associated with poor prognosis in breast cancer patients receiving radiotherapy in Curtis data set, but had no significant prognostic effect in patients not receiving radiotherapy (Fig. 6e), further corroborating the notion that high BARD1 and BRCA1 expression results in resistance to DNA-damaging therapy including chemotherapy and radiotherapy. Here, BRCA1 is linked to breast cancer.