IL2 and neoplasm: Melatonin is a potent immunoenhancer that increases the activity of T and B lymphocytes, monocytes and natural killer (NK) cells and stimulates the secretion of cytokines (interleukin-2 (IL-2), interleukin-6 (IL-6), interleukin-12 (IL-12) and tumor necrosis factor-α (TNF-α)) (Figure 1), thereby leading to oncostasis and the inhibition of tumor spreading [24].