LEP and breast carcinoma: In their meta-analysis to evaluate the association between serum leptin levels and breast cancer risk [63], Gu et al. reported that the apparent discrepancies among the findings were related to the heterogeneity across the studies: different genetic backgrounds, different stages and types of breast cancer, different analytic methods to measure serum leptin levels, different menstrual and treatment status of breast cancer patients, different demographics and clinical characteristics.