En Bloc Versus Conventional Transurethral Resection of Bladder Tumors: A Single-center Prospective Randomized Noninferiority Trial

Background: It has been proposed that en bloc resection of bladder tumor (ERBT) improves the quality of tumor resection. A recent international collaborative consensus statement on ERBT underlined the lack of high-quality prospective studies precluding the achievement of solid conclusion on ERBT. Objective: To compare conventional transurethral resection of bladder tumor (cTURBT) and ERBT. Design, setting, and participants: This study (NCT04712201) was a prospective, randomized, noninferiority trial enrolling patients diagnosed with bladder cancer (BC) undergoing endoscopic intervention. Inclusion criteria were: tumor size ≤3 cm, three or fewer lesions, and no sign of muscle invasion and/or ureteral involvement. For a noninferiority rate in BC staging of 5% (α risk 2.5%; β risk 20%), a total of 300 subjects were randomized to ERBT treatment at a 1:1.5 allocation ratio. Intervention: TURBT and ERBT. Outcome measurements and statistical analysis: The primary outcome was the presence of detrusor muscle at final histology. Secondary outcomes include BC staging, T1 substaging, artifacts, complications, the rate of adjuvant treatment, and oncological outcomes. Results and limitations: From April 2018 to June 2021, 300 patients met the inclusion criteria. Of these, 248 (83%) underwent the assigned intervention: 108 patients (44%) underwent cTURBT and 140 (57%) underwent ERBT. The rate of detrusor muscle presence for ERBT was noninferior to that for TURBT (94% vs 95%; p = 0.8). T1 substaging was feasible in 80% of cTURBT cases versus 100% of ERBT cases (p = 0.02). Complication rates, rates of postoperative adjuvant treatment, catheterization time, and hospital stay were comparable between the two groups (p > 0.05). The recurrence rate at median follow-up of 15 mo (interquartile range 7-28) was 18% for cTURBT versus 13% for ERBT (p = 0.16). Limitations include the single high-volume institution and the short-term follow-up. Conclusions: Our study has the highest level of evidence for comparison of ERBT versus TURBT. ERBT was noninferior to TURBT for BC staging. The rate of T1 substaging feasibility was significantly higher with ERBT. Patient summary: We compared two techniques for removing tumors from the bladder. The en bloc technique removes the tumor in one piece and is not inferior to the conventional method in terms of the quality of the surgical resection and cancer staging assessment.