LEP and breast cancer: Serum LEP abundance is higher in patients with breast cancer than in controls, and higher levels of serum LEP, intratumoral LEP mRNA, and intratumoral ObR isoform mRNA levels have been observed to be poor prognostic predictors in patients with breast cancer.[8,16,40] In this study, we first analyzed the expression of LEP in breast cancer tissues and other malignancies and found that LEP expression in breast cancer was downregulated compared to that in other tumor types.