Clinical Applications of Melatonin in Radiotherapy: a Review

Abstract

Radiotherapy is a treatment method for cancers using ionizing radiation (IR). Radiotherapy-induced complications to normal tissues have been major drawbacks. One of the strategies for preventing or reducing these side effects is the use of natural radioprotectors such as melatonin. Melatonin is largely secreted in the pineal glands of mammals. Studies have evaluated its radioprotective effect mostly using animal models. However, in this review, we discuss the findings of various clinical studies that utilized melatonin in radiotherapy. Online databases (PubMed, Scopus, Embase, and Google Scholar) and ClinicalTrials.gov were searched to retrieve relevant clinical studies which utilized melatonin alongside radiotherapy. The literature reviewed showed that melatonin administration prevented radiation-induced dermatitis, delayed the onset of oral mucositis, and improved treatment outcomes as well as patients’ quality of life after radiotherapy. These studies reported minimal toxicities from melatonin administration. However, their results were not in agreement in terms of patient survival. The application of melatonin in radiotherapy showed potentials for improving treatment outcomes as well as preventing or ameliorating radiotherapy-induced side effects. We recommend further clinical trials for more insights especially in areas such as optimal melatonin dose and patient survival.