Our findings showed no significant association between C3435T polymorphism of ABCB1 and the risk of breast cancer in the dominant model (OR = 0.907; 95 % CI = 0.767–1.073; P = 0.25) as well as the recessive model (OR = 1.181; 95 % CI = 0.973–1.434; P = 0.093), and the allele contrast model (OR = 1.098; 95 % CI = 0.972–1.240; P = 0.133) (Table 6; Fig. 1). The gene discussed is ABCB1; the disease is breast cancer.