Melatonin as an anti-inflammatory agent in radiotherapy

Radiotherapy is one of the most relevant treatment options for cancer therapy with or without other treatment modalities including immunotherapy, surgery and chemotherapy. Exposure to heavy doses of ionizing radiation during radiotherapy results in short and long term side effects. It appears that many of these side effects are linked to inflammatory responses during treatment or after prolonged use. Inflammation is mediated by various genes and cytokines related to immune system responses caused by massive cell death following radiotherapy. This phenomenon is more obvious, particularly after exposure to clinical doses of radiotherapy. Inflammation is involved in the amplification of acute responses, genomic instability and also long term pathological changes in normal tissues. Moreover, inflammation attenuates responses of the tumor to radiotherapy through some mechanisms such as angiogenesis. Thus, the management of inflammation is one of the most interesting aims in cancer radiotherapy. Melatonin, known as a natural product in the body, has been of much interest for its anti-inflammatory properties. Some studies have proposed melatonin as a novel anti-inflammation agent. This literature review will concentrate on the anti-inflammatory properties of melatonin that may help the management of different inflammatory signaling pathways in both tumor and normal tissues.