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 Response Assay (HDRA), on fresh biopsied or surgical specimens. They were 26 bladder 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 renal cell cancer, and the difference was significant for cisplatin, carboplatin, vinblastine, mitomycin C, and adriamycin. There was no significant correlation between the histological grade of the tumor and HDRA sensitivity. IR values showed a wide distribution and cancers could be classified into two groups of sensitive and resistant. This was especially true for 4-hydroxy-ifosfamide. Three bladder cancer patients with evaluable lesions were treated with drugs selected on the basis of the results of the HDRA. One patient achieved a complete response and the other patients showed a partial response. Our results suggest that chemosensitivity is independent of the clinicopathological classification of cancer, and that the HDRA may be useful for selecting the effective anticancer drug for patients with urological cancer.