Melatonin (N-acetyl-5-methoxytryptamine) is an indoleamine with
antioxidant, chronobiotic and anti-inflammatory properties; reduced levels of this
hormone are associated with higher risk of
cancer. Several beneficial effects of
melatonin have been described in a broad number of
tumors, including
liver cancers. In this work we systematically reviewed the publications of the last 15 years that assessed the underlying mechanisms of
melatonin activities against
liver cancers, and its role as coadjuvant in the treatment of these
tumors. Literature research was performed employing PubMed, Scopus and Web of Science (WOS) databases and, after screening, 51 articles were included. Results from the selected studies denoted the useful actions of
melatonin in preventing
carcinogenesis and as a promising treatment option for the primary liver
tumors hepatocellular carcinoma (HCC) and
cholangiocarcinoma (CCA), either alone or in combination with other compounds. Different processes were modulated by the
indole, such as inhibition of oxidative stress, proliferation, angiogenesis and invasion, promotion of immune system response, cell cycle arrest and apoptosis, as well as recovery of circadian rhythms and autophagy modulation. Taken together, the present systematic review highlights the evidence that document the potential role of
melatonin in improving the landscape of liver
tumor treatment.