En Bloc Versus Conventional Resection of Primary Bladder Tumor (eBLOC): A Prospective, Multicenter, Open-label, Phase 3 Randomized Controlled Trial

eBLOC was a randomized, phase 3 superiority trial comparing en bloc transurethral resection of the bladder (TURB) to conventional fragmentation TURB. The trial showed a significantly higher percentage of detrusor muscle and a better safety profile with less bladder perforation for the group resected via en bloc TURB. En bloc transurethral resection of the bladder (eTURB) might improve the surgical management of non–muscle-invasive bladder cancer (NMIBC) in comparison to conventional TURB (cTURB). To evaluate whether eTURB is superior to cTURB in resection of NMIBC and specimen retrieval. Design, setting, and participants: This was a randomized, multicenter trial in patients with up to three cTa–T1 NMIBC tumors of 1–3 cm in size, who were enrolled from January 2019 to January 2022. Intervention: Participants were randomized 1:1 to undergo eTURB (n = 192) or cTURB (n = 192). Outcome measurements and statistical analysis: The primary outcome was the prevalence of detrusor muscle (DM) in the specimen retrieved. Secondary endpoints included bladder perforation, persistent disease at second-look TURB, positive lateral resection margin, positive deep resection margin, operation time, perforation rate, obturator reflex, conversion from eTURB to cTURB, recurrence-free survival, and disease recurrence at 3 mo. and limitations: A total of 384 patients were randomized to undergo eTURB or cTURB. A total of 452 tumors were resected and analyzed for the primary outcome. eTURB was superior to cTURB in retrieval of DM (80.7% vs 71.1%; mixed-model p = 0.01). Bladder perforation (5.6% vs 12%; difference −6.4%; 95% confidence interval [CI] −12.2% to −0.6%) and obturator reflex (8.4% vs 16%; difference −7.6%; 95% CI −14.3% to −0.9%) were less frequent in the eTURB arm than in the cTURB arm. Operation time did not differ between the two techniques (26 min, interquartile range [IQR] 20–38 for eTURB vs 25 min, IQR 17–35 for cTURB; difference 1 min, 95% CI –25.9 to 4.99). Second-look TURB was performed in 24 patients in the eTURB arm and 34 in the cTURB arm, with no difference in the rate of residual papillary disease (pTa/pT1: 56% vs 55.9%; difference 0.1%, 95% CI −25.5% to 25.7%). At median follow-up of 13 mo (IQR 7–20), 18.4% of the patients in the eTURB arm and 16.7% in the cTURB arm had experienced bladder cancer recurrence (Cox hazard ratio 0.87, 95% CI 0.49–1.52; p = 0.6). In patients with clinical NMIBC with up to three tumors of 1–3 cm in size, tumor removal via eTURB res