Radioprotectants to reduce the risk of radiation-induced carcinogenesis

Development of radioprotective agents has focused primarily on cytoprotection from relatively high doses of therapeutic radiation and nuclear disasters. Epidemiological studies and radiobiological models report the potential for stochastic effects from relatively low-dose radiation exposure. Diagnostic studies like computed tomography (CT) expose the patient to a small but significant amount of radiation, which has been reported to increase the risk for carcinogenesis. Young patients expected to undergo multiple CT studies may benefit from a protective agent given prior to CT. This review includes published data of agents that have been shown to protect against radiation-induced carcinogenesis. A discussion follows regarding the data that describes the extent of radiation exposure during CT, as well as technical modifications, which also reduce radiation exposure.

Most experiments have used in vivo animal models or in vitro cell lines. Ethical barriers prevent large-scale human studies, although, there are two prospective human studies from the Chernobyl nuclear accident. Collectively, all of these studies provide evidence of statistically significant reductions in radiation-induced carcinogenesis. Protection is achieved by several mechanisms, which include free radical scavenging, caloric restriction, non-steroidal anti-inflammatory agents, humoral factors, and an oxidative agent. Enhanced efficacy is achieved when targeting multiple mechanisms. The data presented provides the scientific foundation for future development of a radioprotectant that may reduce the risk of carcinogenesis from low-dose exposure when certain at-risk populations undergo diagnostic studies like CT.