CASP8 and breast cancer: After accounting for the four CASP8 signals, rs74943274 retained evidence of an association with overall breast cancer (P=1.44 × 10−3) and a strong association with ER-negative breast cancer (P=1.34 × 10−5; Supplementary Table 16; Supplementary Fig. 2), suggesting that rs74943274 and rs115635831 represents a novel locus associated with ER-negative breast cancer.