AbstractThe effect of 1-β-D-arabinofuranosylcytosine (ara-C) on human bladder transitional cell carcinomas (TCC) was evaluated using nude mouse-grown established tumor lines SW-780, SW-1738, TCC-K1, and PR49. In the nude mouse tumors grew subcutaneously and evaluation of response to treatment was based on tumor volume analysis. Ara-C was administered intraperitoneally at a dosage of 250 mg/kg on days 1 to 4. All four tumor lines showed an initial phase of considerable regression during the treatment week. This was followed by a variable period of tumor growth arrest after which a gradual tumor regrowth was observed. The results of the present study suggested that ara-C may alter the growth rate of TCC, its effect becoming apparent during the time of its administration and for a short period thereafter. These observations indicate that more studies are warranted at both the experimental and clinical levels to further evaluate dosage and treatment schedule. The results of such additional studies may determine the importance of ara-C in the management of patients with bladder cancer.