LEP and cancer: The interrelated mechanisms most often studied in relation to physical activity and cancer prognosis (Fig. 1) include changes in whole-body and visceral fatness, metabolic dysregulation (e.g., insulin, glucose, insulin-like growth factors (IGF)), adipokines (e.g., leptin, adiponectin), and sex hormones (e.g., estrogen, testosterone); chronic, low-grade inflammation; oxidative stress causing DNA damage and gene mutations (e.g., tumor suppressor genes); and impaired immune surveillance/function [11, 41–43].