Radiation Effects on Death and Migration of Tumor Cells in Mice

Inoculation of ¹²⁵ I-iododeoxyuridine labeled tumor cells into nonradioactive hosts permits quantitative evaluations of migration and death of tumor cells in vivo. L1210 leukemia cells inoculated intraperitoneally into C3D2F1J mice die at a rate of 10-14% per day throughout tumor development. In vivo or in vitro irradiation of L1210 cells drastically alters the kinetics and extent of tumor cell death. During the first 2 days after irradiation cell death is not significantly enhanced, even if large doses are administered. This is followed by a period of extremely rapid cell death. Depending on the radiation dose, this killing phase lasts for 2-6 days, and then the death rate returns to normal levels. Mice bearing tumor cells irradiated before transplantation live up to 5 days longer than control mice. However, mice subjected to whole body irradiation after tumor inoculation survive no longer than controls, even though such irradiations also produce large cytocidal effects. This may be ...