MTNR1A and cancer: The anticancer activity was proven in vitro and in preliminary studies in vivo [72], but the concrete mechanism by which melatonin suppresses cancer growth is still to be completely determined, several mechanisms being proposed, such as the repression of the hypothalamic-pituitary-reproductive axis, enhancement of immune function, and direct anti-proliferative effects through various receptors, including melatonin receptor 1a [73].