Of the breast cancer susceptibility loci that had not yet been evaluated for an association with breast cancer in mutation carriers, rs1011970 at CDKN2A/B and rs1292011 at 12q24.21 had significantly different associations with ER-positive and ER-negative cancer for BRCA1 carriers (Phet = 0.009 and Phet = 0.004, respectively, for the difference between ER-positive and ER-negative). This evidence concerns the gene CDKN2A and breast carcinoma.