Seventy-seven patients in a control group without mitomycin-C had a recurrence rate of 65% with a mean follow-up of 33 months. A group of 77 patients treated with 0.4 mg/ml of mitomycin-C, four times per day for 2 weeks, had a recurrence rate of 2.5% with 6 (10%) serious complications (mean follow-up 34 months). A group of 22 patients treated with 0.2 mg/ml of mitomycin-C, four times per day for 10 days, had a recurrence rate of 55% with 3 (7