Abstract
Radiation exposure increases the risk of both leukemia and solid tumors, including the cancer of mammary gland, which is one of the most radiosensitive organs in respect to carcinogenesis. The breast cancer risk is reported to be high in female flight attendants. It is therefore likely that female astronauts, also exposed to cosmic rays, and cancer patients treated with heavy ion therapy may have an increased risk of breast cancer. In order to obtain basic information on the heavy ion-induced mammary carcinogenesis, we irradiated rats of four strains (Sprague-Dawley, F344, Wistar and ACI/N) with 290 MeV carbon beam (LET 50 keV/µm) at doses of 0, 0.5, 1 and 2 Gy, and examined mammary tumor development up to 300 days. It was found that Sprague-Dawley and Wistar rats had high susceptibility, while F344 and ACI/N rats had low susceptibility. The incidence and multiplicity were dose dependent. Pathologically, tumors were mainly adenocarcinomas and fibroadenomas. These results suggest an existence of distinct strain- and dose-dependency in the heavy ion-induced mammary tumor development. [J Radiat Res 44:399-400 (2003)]
