Radon as a risk factor for extra-pulmonary tumours.

Exposure to radon in uranium and other mines is a well recognised risk factor for lung cancer. There is also increasing evidence of a risk of lung cancer from indoor radon. An excess of stomach cancer has been observed in some mining populations but the role of radon is unclear. A few correlation studies and a case-control study have indicated that exposure to indoor radon could be of some importance as a cause of other tumours, especially acute myeloid leukaemia, melanoma and kidney cancer. Also prostate cancer and some other cancer types have correlated with estimated radon exposure but the relatively few studies are not quite consistent with each other. Nevertheless, the various observations of extra-pulmonary tumours associated with radon exposure may warrant further studies, especially with regard to childhood exposure and cancers.