Objectives. To study the influence of adverse reactions on adherence to an immunotherapy maintenance schedule and the recurrence rate of bladder cancer. Bacille Calmette-Guérin immunotherapy has documented efficacy in the management of high-risk superficial bladder cancer. However, the optimal duration of intravesical bacille Calmette-Guérin therapy and the risk/benefit ratio of maintenance therapy are controversial.

Methods. From April 1996 to April 2000, 72 patients with superficial bladder cancer were treated with Immucyst (six consecutive weekly instillations of 81 mg) and then received maintenance therapy consisting of three consecutive weekly instillations 3, 6, 12, 18, 24, 30, and 36 months later. Adverse reactions, studied during 518 instillations, were classified in four categories using a scale based on the World Health Organization recommendations, and their impact on the adherence to therapy was analyzed.

Results. After an average follow-up of 24 months, a durable disease-free response was observed in 84.9% of the patients; 12.5% of patients had a relapse and 2.6% had disease progression. The response rate was similar in patients with and without adverse reactions. Only 14 patients (19%) received all the scheduled maintenance instillations. The dose was reduced in 41 patients (57%), and treatment was stopped in 28 patients (39%). In multivariate analysis, an adverse event score of 1.5 or greater during induction therapy was significantly associated with cessation or modification of maintenance therapy (P = 0.01).

Conclusions. The scale developed in this study to monitor the adverse reactions to bacille Calmette-Guérin and their impact on the adherence to maintenance therapy may be helpful for tailoring maintenance regimens or implementing protective measures (dose reduction or treatment postponement).