The positive association was stronger in ER(+) breast cancer (per allele OR  = 1.29, 95% CI = 1.23–1.36, P = 3.0×10−23) than in ER(−) breast cancer (per allele OR  = 1.19, 95% CI = 1.12–1.26, P = 1.3×10−8). This evidence concerns the gene ESR1 and breast cancer.