An in vitro clonal assay for bladder cancer: Studies of the biologic potential of the urothelium and determination of in vitro sensitivity to cytotoxic agents

We have applied an in vitro colony‐forming assay system to the study of primary urothelial explants obtained transurethrally by bladder barbotage and tumor biopsy from 91 patients. Urothelial cells obtained by bladder barbotage from patients with bladder cancer and from a “control” group of individuals exhibit differential capacity to clone in agar. Of samples from bladder cancer patients, 88% formed colonies, whereas only 27% of these from a “control” group did so. Of samples from a “suspicious” patient group, 70% formed colonies. In vitro drug sensitivity studies of cells obtained by biopsy of solid tumors demonstrate a spectrum of drug sensitivity to cytotoxic agents.