A systematic review and meta-analysis of intraarterial chemotherapy for non muscle invasive bladder cancer: Promising alternative therapy in high tuberculosis burden countries

INTRODUCTION: Local therapies for high risk non-muscle-invasive bladder cancer (NMIBC) such as intravesical chemotherapy (IVC) have shown a high rate of progression and recurrence. Intravesical Bacillus Calmette-Guérin (BCG) for local therapies has been shown to reduce progression and recurrence in patient with NMIBC. However, its potential role is limited in high burden countries for tuberculosis (TB) due to its low specificity that can cause wrong diagnosis or false positive in patients with clinically diagnosed tuberculosis. BCG vaccine that has to be given for most people in tuberculosis endemic countries will induce trained immunity that could reduce the effectivity of intravesical BCG for NMIBC. Moreover, intravesical BCG is contraindicated in patient with or previous tuberculosis. The potential clinical benefit of intraarterial chemotherapy (IAC) in delaying the recurrence and progression of high-risk NMIBC have been investigated with promising results. We aimed to conduct a meta-analysis to evaluate the potential anti-tumor effect of IAC in NMIBC.

METHODS: We conducted a comprehensive search of published articles in Cochrane Library, Pubmed, and Science-Direct to identify relevant randomized controlled trials (RCTs) and observational studies comparing IAC alone or combined with IVC versus IVC/BCG alone in NMIBC. The protocol of preferred reporting items for systematic review and meta-analysis (PRISMA) was applied to this study.

RESULTS: Four RCTs and 4 cohort observational studies were eligible in this study and 5 studies were included in meta-analysis. The risk ratio of tumor recurrence was reduced by 35% (RR = 0.65; 95% CI 0.49-0.87; p = 0.004) in IAC plus IVC, while recurrence-free survival (RFS) was prolonged by 45% (HR: 0.55; 95% CI, 0.44-0.69; p < 0.001). The risk of tumor progression was reduced by 45% (RR = 0.55; 95% CI 0.41-0.75; p = 0.002) and tumor progression-free survival (PFS) was also prolonged by 53% (HR: 0.47; 95% CI, 0.34-0.65; p<0.001). Some RCT's had high or unclear risk of bias, meanwhile 4 included cohort studies had overall low risk of bias, therefore the pooled results need to be interpreted cautiously. Subgroup analysis revealed that the heterogeneity outcome of tumour recurrence might be attributed to the difference in NMIBC stages and grades.

CONCLUSIONS: The IAC alone or combined with IVC following bladder tumor resection may lower the risk of tumor recurrence and progression. These findings highlight the importance of further multi institutional randomized controlled trials with bigger sample size using a standardized IAC protocol to validate the current results.