They reported that obese women had 22% lower risk of premenopausal ER-positive (ER+)/PR+ breast cancer than premenopausal women with BMI lower than 25 kg/m2 (summary risk ratio = 0.78, 95% confidence interval (95% CI) = 0.67–0.92) and 39% higher risk of postmenopausal ER+/PR+ breast cancer than postmenopausal women with BMI lower than 25 kg/m2 (summary risk ratio = 1.39, 95% CI =1.14–1.70). This evidence concerns the gene ESR1 and breast cancer.