Their results confirmed an association between leptin levels and breast cancer risk, and the authors outlined two key conclusions from this meta-analysis: a strong relationship between breast cancer risk and higher leptin levels in patients who were overweight/obese and, secondly, elevated leptin levels in some but not all the studies was associated with breast cancer risk in postmenopausal but not in premenopausal women. This evidence concerns the gene LEP and breast carcinoma.