Application of Hydrogen Producing Microorganisms in Radiotherapy: An Idea

Radiotherapy (RT) is the most widely used cancer treatment modality that plays a pivotal role in the management of wide variety of cancers and malignancies. About 50% of all cancer patients receive radiation treatment during the course of their disease (1). Although by advances in medical technologies the final goal of RT, deliver the highest radiation dose to the tumor volume and sparing surrounding normal tissues, is partially met, but is not enough and normal tissues or organs at risk (OARs) are damaged. Irradiation of OARs particularly in children may causes a wide spectrum of diseases that the secondary cancers are on the front line (2). New radiation related cancer treatment modalities such as intensity modulated radiation therapy (IMRT) potentially elevate secondary exposures to healthy tissues distant from the target volume and therefore more contribute to secondary cancer induction (3). Radiation induced normal tissue complication is a complex process that highly dependent on radiation quality and dose, fractionation scheme, dose rate, total dose, irradiated volume and radiosensitivity, so normal tissue protection can be achieved by different approaches. Of the physical, chemical and biological radiation protection methods, chemical methods that use radioprotectors are more wellknown (4). The mechanisms that implicated by radioprotectors are free-radical scavenging that protects against -based free-radical generation by ionizing radiations and hydrogen-atom donation to facilitate direct chemical repair at sites of DNA damage. Several radioprotectors have been evaluated in clinical trials, human and animal models but the results advice against the use of these substances because of their toxicity.