The modification of radiosensitivity on experimental murine tumor

The modification of the radiosensitivity of murine tumor was studied in vivo using chemicals (mainly radiosensitizers and BRMs) with radiotherapy. Both LD50/5-days (GI death) and LD50/30-days (BM death) for normal tissue response were not enhanced with combined radiotherapy using hypoxic cell radiosensitizers. In addition, radiosensitizing effects to murine tumor with combined radiotherapy showed enhancement of the tumor target cell population. Moreover, no significant differences were found in radiosensitivity between aerobic cells treated by radiation alone and those treated by radiation in combination with radiosensitizers. On the other hand, the dose modifying factor of BRM's in combined radiotherapy of murine tumor was observed, however, the ratio of modification was smaller than the radiosensitizer's effect. It is well known that radiosensitizers can have physiological side effects. The author believes that it is best to employ radiosensitizers that increase the sensitivity only of tumor target cells, not normal cells, thereby allowing greater effects of radiotherapy without increasing overall radiotherapy doses. (author)