The odds of developing ER + PR+ breast cancer was 2.34 (95% CI = 1.18–4.64) among women with late age at first birth (> 27 years) and unmethylated BRCA1 promoters, whereas among women with methylated BRCA1 the OR was 0.88 (95% CI = 0.51–1.51). Here, ESR1 is linked to breast cancer.