Intravesical mitomycin C instillation as a prophylactic treatment of superficial bladder tumor.

A study was performed to determine the prophylactic efficacy of intravesical mitomycin C instillation in 43 patients with recurrent (more than 3), multiple (more than 3) or large (more than 3 cm.) superficial bladder tumors (stage Ta or T1). Of the patients 21 were treated with 8 weekly intravesical instillations of 40 mg. mitomycin C after transurethral resection and 22 were followed conventionally. The recurrence rate was 42.9 per cent in the mitomycin C group and 40.9 per cent in the controls during the first 3 months, and it was 81.0 and 77.3 per cent, respectively during 24 months. Recurrences per 100 patient-months were 8.7 and 8.9, respectively. Two patients in the mitomycin C group and 4 controls had recurrent tumors with progression in stage. We conclude tentatively from these observations that intravesical mitomycin C instillation is not effective in the prophylaxis of tumor recurrence in patients at high risk. This finding is contrary to other reports indicating a marked decrease in recurrence with mitomycin C.