HZE radiation effects for hereditary renal carcinomas.

ABSTRACT

Eker rat known as a model of hereditary renal carcinoma (RC) is an example of Mendelian dominantly inherited predisposition to a specific cancer in experimental animals. We investigate the effects of simulated space radiation on carcinogenesis using HIMAC. We estimated RBE from the Eker rats exposed to the heavy-ions, C (290 MeV/u) and Fe (500 MeV/u) ions, comparing to the effects of X-ray irradiation. Pregnant rats were exposed to C and Fe ions and X-rays with a single dose of 1 Gy, 2 Gy, 3 Gy on day 19 of gestation. The offspring were sacrificed at 8 weeks of age. We evaluated organ weights and tumor genesis. The weights of thymus, lung, liver, spleen were found to be no difference from the control at 1 Gy irradiation but 50% decrease at 3 Gy irradiation. We found in the irradiated animal that kidney, brain and testis were very sensitive organs of which the weight decreased to approximately 80% at 1 Gy and to 40% at 3 Gy irradiations. Based on the dose-response relationship of the radiation-induced carcinoma, averaged RBE ware calculated to be 1.1 for C-ion, 1.6 for Fe-ion.