An elevated cholesterol level is an obesity comorbidity, and studies suggest that the effects of obesity on cancer may be partly mediated by increased cholesterol levels.216 In fact, a high-cholesterol diet (HCD) alone has been shown to promote macrophage infiltration and significantly enhance the growth of CRC tumors.217 One mechanism by which HCD promotes CRC progression is through the inhibition of the CD8+ T-cell response. The gene discussed is CD8A; the disease is obesity due to melanocortin 4 receptor deficiency.