Radiation-induced bystander effects — implications for cancer

The term radiation-induced bystander effects describes a situation where cells that have not been directly exposed to ionizing radiation behave as though they have been exposed: they die or they show chromosomal instability and other abnormalities. The bystander cells might be immediately adjacent or might be some distance away from the exposed cell. Although the nature of the communication system that is involved in producing these responses is not yet known, there is strong evidence for a chemical signalling process that transmits information from the irradiated cell to neighbouring cells. The bystander effect has several important implications for radiation protection, radiotherapy and diagnostic radiology.