DISEASE CHARACTERISTICS: Histologically confirmed completely resected T1 or Ta papillary tumors of the urinary bladder TaG2 greater than 2 relapses in 2 years TaG3 unifocal or multifocal Unifocal primary T1G2-3 after a histological tumor-free second resection If multiple/multifocal, worst stage and grade AND/OR Histologically and cytologically confirmed primary or secondary carcinoma in situ of the urinary bladder No persistent T1 disease in second resection No contracted bladder (bladder capacity less than 80 mL) or bladder irritation within past 5 years No urothelial carcinoma of the upper urinary tract or the urethra