When waist circumference was included as a covariate, breast cancer risk associated with circulating leptin was further increased in premenopausal women (comparison for highest to lowest quartile, HR = 1.99 (95% CI, 1.06–3.39)) and postmenopausal women (comparison for highest to lowest quartile, HR = 3.25 (95% CI, 1.53–6.91)) [88]. Here, LEP is linked to breast cancer.