The impact of second transurethral resection on survival outcomes in patients with non-muscle-invasive bladder cancer treated with bacillus Calmette-Gurin therapy

Objective Several guidelines recommended that second transurethral resection should be performed in patients with diagnosis of high-risk non-muscle-invasive bladder cancer. However, therapeutic benefits of second transurethral resection before bacillus Calmette-Guerin intravesical instillation were conflicting amongst previous studies. We investigated the prognostic impact of second transurethral resection before bacillus Calmette-Guerin instillation in high-risk non-muscle-invasive bladder cancer patients.Methods This retrospective study included 3104 non-muscle-invasive bladder cancer patients who received bacillus Calmette-Guerin instillations between 2000 and 2019 at 31 collaborative institutions. Univariate and multivariate Cox proportional hazards models were used to assess the risk factors of intravesical recurrence, disease progression, cancer-specific mortality and overall mortality.Results In the entire population, patients undergoing second transurethral resection (33%, 1026/3104) had a lower risk of intravesical recurrence on univariate analysis (hazard ratio 0.85, 95% confidence interval 0.73-0.98, P = 0.027), although it did not remain significant on multivariate analysis (hazard ratio 0.90, 95% confidence interval 0.76-1.07, P = 0.24). Subgroup analysis revealed that, in pT1 patients (n = 1487), second transurethral resection was significantly correlated with a lower risk of intravesical recurrence on multivariate analysis (hazard ratio 0.80, 95% confidence interval 0.64-1.00, P = 0.048), but lower risks of disease progression (hazard ratio 0.75, 95% confidence interval 0.56-1.00, P = 0.049), cancer-specific mortality (hazard ratio 0.54, 95% confidence interval 0.35-0.85, P = 0.007) and overall mortality (hazard ratio 0.73, 95% confidence interval 0.55-0.97, P = 0.027) on univariate analysis.Conclusions Second transurethral resection confers accurate pathological staging and could be used to safely select good candidates for intravesical bacillus Calmette-Guerin instillation. We further confirm that second transurethral resection could confer an oncological benefit in pT1 bladder cancer patients treated by bacillus Calmette-Guerin instillation, and so strongly recommend second transurethral resection in this patient population. Second transurethral resection reduced intravesical recurrence, disease progression and cancer-specific mortality in pT1 bladder cancer patients treated by bacillus Calmette-Guerin instillation from the largest Japanese cohort.