Compared to the women without diabetes, the increased risk of breast cancer by diabetes was more obvious among women with the CC genotype [OR (95%CI): 2.53 (1.45, 4.41)] than those with CG/GG genotypes [1.10 (0.57, 2.10)] of IL-6 rs1800796 and the interaction was significant in a multiplicative model but not in an additive model (P values: 0.048 and 0.294, respectively) (Table 3). This evidence concerns the gene IL6 and breast carcinoma.