Further subgroup analysis by ethnicity indicated that the BACH1 919Ser polymorphism may decrease the risk of breast cancer among Caucasian populations (Ser allele versus Pro allele: OR=0.90, 95% CI=0.86–0.95, P<0.001; Pro/Ser + Ser/Ser versus Pro/Pro: OR=0.90, 95% CI=0.84–0.98, P=0.012; Ser/Ser versus Pro/Pro + Pro/Ser: OR=0.84, 95% CI=0.76–0.92, P<0.001; Ser/Ser versus Pro/Pro: OR=0.81, 95% CI=0.73–0.91, P<0.001; Ser/Ser versus Pro/Ser: OR=0.86, 95% CI=0.78–0.95, P=0.002). This evidence concerns the gene BACH1 and breast cancer.