Negative associations were observed in postmenopausal women (RR = 0.88, 95% CI, 0.75–1.02, P = 0.10), estrogen receptor positive BC (RR = 0.83, 95% CI, 0.64–1.07, P = 0.15), and studies using 12-hour overnight urine (RR = 0.81, 95% CI, 0.61–1.07, P = 0.13), all with borderline significances. Here, ESR1 is linked to breast cancer.