Experimental studies on the radiation-modifying effect of cis-diamminedichloroplatinum II (DDP) in human bladder...

The effect of cis-diamminedichloroplatinum II (DDP) and ionizing radiation on human bladder transitional cell carcinoma (TCC) was evaluated in nude mouse-grown human tumors following administration of single-agent and combination treatment. Combination of DDP and radiation resulted in accelerated tumor regression and substantially delayed tumor regrowth. The potentiating effect of DDP on ionizing radiation was related to timing and sequence of treatments and was independent of tumor sensitivity to DDP. Best results, as judged by tumor growth curve characteristics, histopathologic changes, and absence of tumor metastases, were obtained when DDP was administered at an early stage following radiation treatment.