Oral mucositis and melatonin

Mucositis, one of the most severe toxic side effects of cancer therapy, can affect the entire gastrointestinal tract, with the oral cavity being the most common affected site. It presents in virtually all head and neck cancer patients receiving chemo and/or radiotherapy, in 60-85% of those receiving myeloablative therapy for stem-cell transplantation, and in 20-40% of patients receiving conventional chemotherapy. The use of concomitant chemotherapy and/or targeted agents increases the risk of mucositis. Oral lesions lead to considerably decreased quality of life in these patients due to solid and liquid food dysphagia, dysarthria, and odynophagia, resulting in depression in some patients, who often require percutaneous endoscopic gastrostomy tube insertion. In addition, mucositis lesions may represent a gateway for opportunistic infections, can complicate cancer treatment, and extend hospitalization. On the other hand, given its dose-limiting toxicity for both chemo and radiotherapy, mucositis can have a direct impact on survival rates. As ROS are involved in the manifestation of precancerous lesions such as leukoplakia and lichen planus, melatonin plays a preventative or therapeutic role against oral cancer due to its antioxidant properties. Additionally, melatonin prevents damage to healthy tissues due to radiotherapy, which is routinely employed to treat oral cancers. A recent in vitro study suggests that melatonin may impede metastasis of oral cancer by inhibiting metalloproteinase-9 activation. Therefore, oral rinses, gels, and toothpastes containing melatonin may be beneficial for impeding and preventing oral cancer.