Value of an Immediate Intravesical Instillation of Mitomycin C in Patients with Non–muscle-invasive Bladder Cancer: A Prospective Multicentre Randomised Study in 2243 patients

The efficacy of an immediate single chemotherapy instillation after transurethral resection of a bladder tumour (TURBT) in patients with non-muscle-invasive bladder cancer (NMIBC) remains a topic of debate. Evidence is even more scarce when an immediate instillation is followed by adjuvant instillations.To compare the effect of a mitomycin C (MMC) instillation within 24h to an instillation 2 wk after TURBT in patients with NMIBC with or without adjuvant instillations.Between 1998 and 2003, 2844 NMIBC patients were randomised for immediate versus delayed MMC instillation after TURBT. Patients were categorised in low-risk (LOR), intermediate-risk (IMR), and high-risk (HIR) groups. Total numbers of instillations in these groups were 1, 9, and 15, respectively.Primary end point was 3-yr recurrence risk for the IMR and HIR groups and 5-yr risk for the LOR group. Secondary outcomes were time to recurrence and incidence of adverse events. Analyses were performed with the log-rank test, Cox-regression, and χ2 test in SPSS.A total of 2243 patients were eligible on an intention-to-treat basis. Recurrence risks were 43% and 46% in the LOR group (5-yr follow-up, p=0.11), 20% and 32% in the IMR group (3-yr follow-up, p=0.037), and 28% and 35% in the HIR group (3-yr follow-up, p=0.007), for an immediate and a delayed instillation, respectively. For all patients, the recurrence risk was 27% (95% confidence interval [CI], 24-30) in the immediate and 36% (95% CI, 33-39) in the delayed instillation group (p<0.001) with a 27% reduction in relative recurrence risk (hazard ratio: 0.73, 95% CI, 0.63-0.85, p<0.001). The incidence of adverse events did not differ significantly between treatment groups (immediate instillation 25%, delayed instillation 22%, p=0.08). The risk groups in our study differ slightly from the current guidelines, which is a limitation of our study.An immediate, single instillation after TURBT reduces the recurrence risk in NMIBC patients, independent of the number of adjuvant installations.A single instillation of chemotherapy after the resection of non-muscle-invasive bladder cancer reduces the recurrence risk, even if patients are treated with an adjuvant schedule of instillations.