RADIOSENSITIZING EFFECT OF CISPLATIN IN PROSTATE-CANCER CELL-LINES

The radiosensitizing effect of platinum compounds has been demonstrate d in a number of tumors. In prostate cancer, clinical and preclinical data concerning an eventual efficacy of the concept of radiosensitizat ion are lacking. In the present study cisplatin and carboplatin have b een used as a modal to explore radiosensitization in in vitro prostate cancer cell lines. Human (DU-145) and rat (R3327-MATLyLu) prostate tu mor cells were irradiated with doses ranging from 0 to 8 Gy in the pre sence of various concentrations of either cisplatin or carboplatin. Fo r the evaluation of the combined effect of the two treatment modalitie s, a simple model is presented. Supra-additive treatment effects of co mbinations of platinum drugs with radiotherapy, both at clinically ach ievable doses, were shown on the basis of surviving fractions of tumor cells and proved to be significant. These data strongly suggest that radiotherapy may be effectively combined with radiosensitizers such as platinum drugs in prostate cancer therapy, to yield synergism in trea tment efficacy.