Post-Bacille Calmette–Guerin surveillance for non-muscle invasive bladder cancer: do random biopsies offer an advantage?

Abstract
Background
The optimal surveillance method for recurrence of non-muscle invasive bladder cancer (NMIBC) after intravesical BCG treatment is unknown. The aim of this study is to assess the difference between two surveillance methods: cystoscopy with bladder biopsies and office-based flexible cystoscopy in detecting NMIBC recurrence and time to recurrence.

Methods
Charts of patients who underwent transurethral resection of bladder tumor with subsequent intravesical Bacillus Calmette–Guerin (BCG) treatment were reviewed between January 2015 and December 2018. Baseline demographics and oncological parameters were compared between the two methods of surveillance. Then, the role of the surveillance method for NMIBC recurrence and time to recurrence were evaluated in backward logistic regression and hazard ratios estimated in Cox regression models, respectively.

Results
Fifty-one patients (50.5%) underwent office-based flexible cystoscopy and 50 patients (49.5%) had bladder biopsies. The patients undergoing either surveillance methods were comparable for baseline demographic and oncological parameter. The predictors of recurrence and earlier BCG relapse were increased body mass index, the presence of multifocal tumors, the presence of concurrent carcinoma in situ, and tumor size at presentation. Bladder cancer recurrence was mostly affected by multifocality of the disease [OR 3.61 95%CI (1.17–11.15)] and the presence of concomitant carcinoma in situ [4.35 (1.29–14.68)]. Yet, the surveillance method neither predicted a higher recurrence yield nor earlier diagnosis.

Conclusion
In our cohort, there is neither difference in recurrence yield nor earlier diagnosis of recurrence between office-based flexible cystoscopy and bladder biopsies. Larger prospective studies are needed to assess the generalizability of these findings.