ESR1 and breast cancer: Among the three ESR1 polymorphisms, rs2881766 was found to reduce BC risk under homozygous model (GG vs. TT: OR = 0.63, 95% CI = 0.44–0.91) and recessive model (GG vs. TT/GT: OR = 0.68, 95% CI = 0.49–0.95).