Background: To elucidate the most efficient topical therapy for carcinoma in situ of the bladder, the efficacy of intravesical mitomycin C plus doxorubicin therapy was compared with bacillus Calmette-Guerin (BCG) therapy. The clinical behavior of the tumor was analysed according to the histological grade.
Methods: Forty-two patients with carcinoma in situ of the bladder were randomized to intravesical BCG (21 patients) or mitomycin C plus doxorubicin sequential therapy (21 patients) as first line treatment. The non-responders underwent the subsequent instillation of the other intravesical therapy alternately. Of the patients, 27 had grade 2 and 15 had grade 3 cancer.
Results: Both topical therapies were equally effective with initial response rates of 86% (18/21) for BCG and 81% (17/21) for mitomycin C plus doxorubicin, irrespective of the tumor grade. Of seven initial non-responders, five patients achieved a complete response by subsequent instillation, resulting in a total response rate of 95%. After a mean follow-up of 47 months, five patients (12%) developed disease progression. The progression rates were not different between the topical therapies, but were significantly higher in grade 3 than in grade 2 cases.
Conclusion: It appears likely that mitomycin C plus doxorubicin instillation has an equivalent efficacy to BCG as the initial therapy of carcinoma in situ and the combination of them would be the most efficient treatment for the disease. Moreover, histological grading would be clinically useful in defining the tumor characteristics and behavior of carcinoma in situ of the bladder.