Clinical application of an in vitro chemosensitivity test, the Histoculture Drug Response Assay, to urological cancers: wide distribution of inhibition rates in bladder cancer and renal cell cancer

To investigate the variations in chemosensitivity of individual cancers, we performed an in vitro chemosensitivity test, the Histoculture Drug Respons e Assay (HDRA), on fresh biopsied or surgical specimens. They were 26 bladd er cancers and 19 renal cell cancers. Ten anticancer drugs were tested. By prolonging the drug exposure time to 7 days, we obtained reliable results. The mean inhibition rates (IRs) were higher for bladder cancer than for ren al cell cancer, and the difference was significant for cisplatin, carboplat in, vinblastine, mitomycin C, and adriamycin. There was no significant corr elation between the histological grade of the tumor and HDRA sensitivity. I R values showed a wide distribution and cancers could be classified into tw o groups of sensitive and resistant. This was especially true for 4-hydroxy -ifosfamide. Three bladder cancer patients with evaluable lesions were trea ted with drugs selected on the basis of the results of the HDRA. One patien t achieved a complete response and the other patients showed a partial resp onse. Our results suggest that chemosensitivity is independent of the clini copathological classification of cancer, and that the HDRA may be useful fo r selecting the effective anticancer drug for patients with urological canc er.