Impact of carcinoma in situ on the outcome of intravesical Bacillus Calmette-Guérin therapy for non-muscle-invasive bladder cancer: a comparative analysis of large real-world data

Background: This study investigated the clinical impact of carcinoma in situ (CIS) in intravesical Bacillus Calmette-Guérin (BCG) therapy for patients with non-muscle-invasive bladder cancer (NMIBC). Methods: This study retrospectively evaluated 3035 patients who were diagnosed with NMIBC and treated by intravesical BCG therapy between 2000 and 2019 at 31 institutions. Patients were divided into six groups according to the presence of CIS as follows: low-grade Ta without concomitant CIS, high-grade Ta without concomitant CIS, high-grade Ta with concomitant CIS, high-grade T1 without concomitant CIS, high-grade T1 with concomitant CIS, and pure CIS (without any papillary lesion). The endpoints were recurrence- and progression-free survival after the initiation of BCG therapy. We analyzed to identify factors associated with recurrence and progression. Results: At a median follow-up of 44.4 months, recurrence and progression were observed in 955 (31.5%) and 316 (10.4%) patients, respectively. Comparison of six groups using univariate and multivariate analysis showed no significant association of CIS. However, CIS in the prostatic urethra was an independent factors associated with progression. Conclusion: Concomitant CIS did not show a significant impact in the analysis of Ta and T1 tumors which were treated using intravesical BCG. Concomitant CIS in the prostatic urethra was associated with high risk of progression. Alternative treatment approaches such as radical cystectomy should be considered for patients with NMIBC who have a risk of progression.