COMPARISON OF SENSITIVITIES OF CELLS TO X-RAY THERAPY, CHEMOTHERAPY, AND ISOTOPE THERAPY USING A TUMOR SPHEROID MODEL

Numerous treatment modalities have been used in treating microscopic c arcinoma confined to the peritoneal cavity. However, there is little i nformation at the cellular level regarding which modality is most effe ctive in eradicating small nests of tumor cells. In order to determine whether chemotherapy, X rays, or isotope therapy is most effective, w e have compared in a three-dimensional spheroid model the survival of cells after treatment with cts-platinum, X ray, or the investigational high-energy isotope 212-bismuth (Bi-212). In this study, V-79 cells w ere grown to 100-mu m diameter spheroids. In killing spheroids, high-e nergy isotopes were at least six times more effective than X rays at f ractionated doses of up to 1300 cGy. High-energy isotopes appear also to be as efficient as cis-platinum. Regardless of exposure time to tre atment, Bi-212 was more toxic to spheroids than the other treatment mo dalities. From this study we conclude that high-energy isotope therapy biologically is very effective in eradicating microscopic nests of ce lls. (C) 1994 Academic Press, Inc.