PDCD6IP and breast cancer: Our findings revealed that the PDCD6IP 15 bp I/D polymorphism decreased the risk of BC in codominant (OR = 0.44, 95% CI = 0.31–0.65, p < 0.0001, I/D versus DD; OR = 0.39, 95% CI = 0.17–0.88, p = 0.030, I/I versus DD) and dominant (OR = 0.44, 95% CI = 0.30–0.63, p < 0.0001, D/I + I/I versus D/D) tested inheritance models.