Comparative study on radiosensitivities of cultured cell lines derived from several human tumors under hypoxic condition.

Three human cell lines, Burkitt lymphoma cells (P3HR-1), epidermoid carcinoma cells (HeLa S3-1), and melanoma cells (HMV) were irradiated with 200 kV X-rays under three different oxygen conditions. The values of D0 and D10(-2) were estimated for survival curves, and then the dose-modifying factors (DMF) were calculated, for the oxygenated and hypoxic irradiations. These DMF values for oxygenation were not different for each cell line, but those for hypoxia revealed considerable difference for cell lines. From the comparison of modifications due to variable oxygen concentrations on the survival curves of Burkitt lymphoma cells with those of other resistant cells, it is concluded that the shoulder of the survival curves becomes larger primarily with lowering of the oxygen tension, and then D0 value increases followed by a decrease in n value, while in oxygenation, the decrease in D0 value takes place after n value becomes close to 1.