LEP and breast cancer: However, similar to our results, three prospective studies reported an inverse association between breast cancer risk with leptin levels [EPIC-Varese cohort: ORT3 vs. T1=0.42 (0.21–0.84) [22]; Nurses’ Health Study II cohort: OR Q4 vs. Q1 = 0.69 (0.38–1.23) [16]; The Northern Sweden Health and Disease Cohort: ORT3 vs. T1= 0.80 (0.52–1.22) [23]].