Radiosensitivity of different human tumor lines grown as xenografts determined from growth delay and survival data

Four human tumor lines were grown as xenografts in nude mice to determine whether xenografts derived from different types of tumors would show tumor-type dependent differences in response to single-dose irradiation, and whether these differences, paralleled clinical behavior. Xenografts from a neuroblastoma, a squamous cell carcinoma, a melanoma and a lung adenocarcinoma were studied in terms of growth delay and tumor control dose (TCD50). To exclude an immunoreaction of the host in the radiation response of the tumor xenografts, the tumor lines were tested for their growth in immunosuppressed Wistar rats. No differences in growth of xenografts in either immunodeficient mice or immunosuppressed rats were observed. Both growth delay and local tumor control as expressed by cure correlated well with clinical behavior of the tumor types of origin. This study demonstrates that radiosensitivity of different human tumor lines can be evaluated in terms of growth delay and tumor control dose50 when they are grown as xenografts. To exclude immune reactions, proper controls should be included. The sensitivities established from these evaluations parallel clinical behavior, thus offering a tool for analysis of human tumor radiosensitivity of histologically different tumor types.