The two SNPs close to CCND1 were strongly associated with low/intermediate grade DCIS (rs75915166, OR 1.36, 95 % CI 1.17, 1.59; P = 7.2 × 10-5; rs554219, OR 1.32, 95 % CI 1.18, 1.48; P = 8.2 × 10-7) and there was no association with high grade DCIS (Table 2). Here, CCND1 is linked to ductal breast carcinoma in situ.