A Systematic Review and Meta-analysis of Chemoablation for Non-muscle-invasive Bladder Cancer

Context: The ablative effect of intravesical therapy is known for decades. However, the clinical feasibility and efficacy of chemoablation for non-muscle-invasive bladder cancer (NMIBC) have not become accepted. Objective: To assess the treatment outcomes of chemoablation for NMIBC and to compare its safety with that of the standard treatment, transurethral resection of bladder tumors (TURBT) followed by intravesical therapy. Evidence acquisition: Multiple databases were queried in July 2022 for studies investigating the complete response (CR) rates and adverse events in NMIBC patients treated with chemoablation using mitomycin C (MMC), gemcitabine, epirubicin, or bacillus Calmette-Guerin. Evidence synthesis: Overall, 23 studies comprising 1199 patients were eligible for this meta-analysis. Among these studies, 20 assessed the efficacy of chemoablation and three compared the treatment outcomes of MMC chemoablation versus standard treatment. Among patients treated with weekly administration of any agent, the pooled CR rates at initial assessment were 50.9% (95% confidence interval [CI]: 45.9-55.9) for the marker lesion and 47.5% (95% CI: 36.5-58.7) for well-selected NMIBC (ie, small tumors and/or a small number of tumors). Novel regimens for chemoablation such as MMC-gel (70.6%, 95% CI: 60.1-79.3) and an intensive MMC regimen (64.7%, 95% CI: 56.2-72.3) provided better CR rates inwell-selected NMIBC patients. Comparable CR rates were noted irrespective of tumormultiplicity, whereas tumor size <5mm was associated with a higher CR rate than tumor size >= 5 mm (odds ratio: 0.36, 95% CI: 0.17-0.79). The novel intensive MMC regimen resulted in lower rates of dysuria and urinary frequency than standard treatment. Conclusions: Despite the lack of long-term outcomes, chemoablation appears to be a promising treatment option for well-selected NMIBC patients and can potentially help avoid unnecessary TURBT, specifically in some elderly patients with intermediate-risk NMIBC. Further well-designed studies with larger cohorts are necessary to address the differential tolerability and long-term anticancer efficacy of this resurging approach. Patient summary: Bladder instillation therapy has a potential ablative effect for well-selected non-muscle-invasive bladder cancer. This can lead to the omission of an unnecessary surgical treatment. (c) 2022 The Author(s). Published by Elsevier B.V. on behalf of European Association of Urology. This is an open access article under the CC BY license (http://creativecommons. org/licenses/by/4.0/).