Predictive factors for residual cancer in second transurethral resection for non-muscle-invasive bladder cancer

Background/Aim: The significance of second transurethral resection (TUR), and identification of predictive factors for residual cancer remain unrevealed. This study aimed to find residual cancer and up-staging rates, as well as predictive factors for residual cancer, in patients who undergo second TUR for non-muscle-invasive bladder cancer (NMIBC). Patients and Methods: Patients who underwent second TURs for NMIBC between 2015 and 2017, were included in the study and their clinicopathological characteristics were analyzed for predictors of residual cancer. Results: Among 143 Japanese patients whose tumors were initially diagnosed as high-risk NMIBC, residual cancers detected at second TURs were, Tis: n=22 (15.4%), Ta: n=15 (10.5%) and T1: n=29 (20.3%). No patients showed upstaging from NMIBC to MIBC. The presence of carcinoma-in situ at initial TUR was an independent risk factor for any residual cancer (Tis, Ta and T1), non-flat residual cancer (Ta and T1), and flat residual cancer (Tis). Conclusion: The presence of carcinoma-in situ is suggested to be an independent predictor of residual cancer. This may help guide decisions to perform second TUR.