Radiation and non-Hodgkin's lymphoma.

Lymphomas are rarely, if ever, found to be in excess following exposure to ionizing radiation. Hodgkin's disease has never been linked to radiation, and the evidence for non-Hodgkin's lymphoma (NHL) is very weak. Low doses of radiation from diagnostic X-ray procedures or from occupational exposures do not appear to cause NHL. Mortality studies of atomic bomb survivors in Japan and other epidemiological studies with quantitative estimates of radiation dose also fail to find dose-response relationships. NHL may arise infrequently following high-dose, possibly near lethal, radiation treatments. Immunosuppression associated with the disease being treated, such as Hodgkin's disease, may contribute to the development of NHL. If radiation does not cause NHL, at least not by its accepted mechanism of action of breaking chromosomes, creating rearrangements, gene deletions, and mutations, perhaps other environmental mutagens and clastogens should not be considered likely causes of NHL.