Effect of continuous saline bladder irrigation with concomitant single instillation of chemotherapy after transurethral resection on intravesical recurrence in patients with non‑muscle‑invasive bladder cancer

A single immediate instillation of chemotherapy following transurethral resection of bladder tumor (TURBT) is effective in preventing intravesical recurrence (IVR) in patients with non-muscle-invasive urothelial bladder carcinoma (NMIBC). However, continuous saline bladder irrigation (CSBI) is also performed with a single instillation of chemotherapy (SIC), but its inhibitory effect on IVR remains unclear. In the present study, the effect of CSBI with concomitant SIC following TUR on IVR was evaluated in patients with NMIBC. A retrospective review of 253 patients who underwent TURBT and were clinically and histologically diagnosed with NMIBC at National Defense Medical College Hospital was performed. Doxorubicin (DXR) was administered to all patients. Methods of DXR administration included a single instillation of DXR (60 mg in 30-40 ml saline) in 34 patients (group A), continuous irrigation of the bladder with saline including DXR (80 mg in 1 liter saline) in 40 patients (group B) and overnight CSBI after a single instillation of DXR in 179 patients (group C). The difference in IVR-free survival rates was compared after adjusting for significant differences in several covariates between the groups by nearest-neighbor propensity score matching. Prior to propensity score matching, it was identified that time to IVR was significantly longer in group A than in groups B and C; however, it was observed that several factors significantly differed among the three groups. By using nearest neighbor matching, 18 pairs were matched between groups A and B and 33 pairs between the groups A and C. No significant difference was identified in any covariates between these two matched group pairsTime to IVR was significantly longer in the matched group A than in the matched groups B and C (P=0.0255 and P=0.0023, respectively). In conclusion, SIC alone could provide a higher IVR-free survival rate than CSBI with DXR or CSBI with SIC.