DISEASE CHARACTERISTICS: Histologically confirmed low grade (grade 1 or 2), superficial (stage Ta or T1) transitional cell carcinoma (TCC) of the bladder Newly diagnosed or recurrent All visible tumor must have been resected within the past 12 weeks Standard clinical management determined to be expectant observation without further surgery, intravesical therapy, or systemic therapy No prior upper tract TCC No history of grade 3 TCC, carcinoma in situ including severe dysplasia, non-TCC histology, or TCC greater than or equal to T2 No involvement of upper urinary tract prior to or at the time of initial tumor resection Abdominal CT scan, IVP, or retrograde pyelogram within the past 3 months to rule out upper urinary tract tumor