Sequential combination of mitomycin C plus bacillus Calmette-Guérin (BCG) is more effective but more toxic than BCG alone in patients with non-muscle-invasive bladder cancer in intermediate- and high-risk patients: final outcome of CUETO 93009, a randomized prospective trial

Abstract

Background: Intravesical bacillus Calmette-Guérin (BCG) is an effective therapy in non-muscle-invasive bladder cancer (NMIBC), but it has limitations in terms of recurrence and toxicity.

Objective: To determine whether the sequential combination of mitomycin C (MMC) and BCG is superior to BCG alone in increasing a disease-free interval (DFI).

Design, setting, and participants: We conducted a prospective randomized trial including 407 patients with intermediate- to high-risk NMIBC and allocated 211 to the MMC and BCG arm and 196 to the BCG-alone arm.

Outcome measurements and statistical analysis: The trial was designed to provide concurrently a power of 80% for the detection of a relative risk reduction of 35% (hazard ratio [HR]: 0.65) of disease relapse with a type I error of 0.05. Times to events were estimated using cumulative incidence functions and compared using the Cox regression model. We used the Kaplan-Meier technique to estimate survival curves.

Results and limitations: In the intention-to-treat analysis at 5 yr, DFI was significantly improved by the sequential scheme (HR: 0.57; 95% confidence interval [CI], 0.39-0.83; p=0.003), reducing the disease relapse rate from 33.9% to 20.6%. Higher toxicity was observed with the combination, even reducing the MMC dose, especially in G3 local toxicity compared with BCG with a difference of 17.4% (95% CI, 7.6-27.2; p<0.001). In recurrent T1 tumors, the potential benefit of the sequential scheme was more evident than in the remaining subgroup (18.8% vs 12.8%), with a number needed to treat of five versus eight to avoid an event and with similar toxicity.

Conclusions: Although the sequential scheme is more effective than BCG alone in reducing disease relapse, due to higher toxicity it could be offered only to patients with a high likelihood of recurrence, such as those with recurrent T1 tumors.

Patient summary: We analyzed the outcomes of a randomized trial demonstrating that in intermediate- to high-risk non-muscle-invasive bladder cancer, mitomycin C and bacillus Calmette-Guérin (BCG) reduced disease relapse compared with BCG alone but was more toxic. Consequently, it could be offered only to patients with recurrent T1 tumors.

Trial registration: CUETO 93009.

Keywords: BCG; Intermediate- to high-risk groups; MMC plus BCG; Randomized trial; Subgroup analysis.