Correlation of human bladder tumor recurrence with changes in clonogenicity of urothelial cells

Over a 2-year period 340 cystoscopies were performed on 174 patients (126 men and 48 women) followed up for previously treated transitional cell tumor of the bladder or new cases suspected of having bladder tumor. Bladder washings taken at cystoscopy in 66% yielded cells for clonogenic assay. Patients with transitional cell tumors had an average clonogenic index (CI) of 14 (+/- 5) colonies per 10(5) viable urothelial cells, whereas previously tumorous patients with tumor-free bladders had an average CI of 6 +/- 1 colonies (P less than 0.001, Student's t test). Patients with hematuria but no bladder tumor had an average CI of 8 (not significant). In serial examinations with consecutive successful clonogenic assay, 11 of 16 patients remaining tumor-free had constant or falling CI whereas 9 of 12 patients with recurrent tumor had rising CI values (Fisher; P less than 0.025). Changes in the clonogenic index of cells taken from bladder washings paralleled the changes in tumor status at cystoscopy and might have predictive value in this disease.