Histopathological Advantages of En Bloc Resection in Non–muscle-invasive Bladder Cancer: A Multinational Randomised Controlled Clinical Trial

Background and objective En bloc resection of bladder tumours (ERBT) has been proposed as an alternative to conventional transurethral resection of bladder tumours (cTURBT) for non–muscle-invasive bladder cancer (NMIBC), potentially improving clinical outcomes and pathological specimen quality. This randomised controlled trial (RCT) compared pathological staging and grading consistency, thermal damage, and specimen orientation between ERBT and cTURBT. Methods In this multinational RCT, patients with suspected NMIBC tumours measuring 1–4 cm were randomised 1:1 to ERBT or cTURBT. A central pathology review was conducted. The primary end point was T-stage concordance between central review and initial pathology assessment. Secondary outcomes included thermal damage and loss of orientation (fragments lacking epithelial cells or detrusor muscle). Surgical outcomes and complications were also evaluated. Key findings and limitations Across 11 sites in five countries, 220 patients were randomised (110 ERBT, 110 cTURBT). For pathology review, 209 cases (103 ERBT, 106 cTURBT) were available. T-stage concordance was 80% (ERBT) versus 81% (cTURBT), corresponding to a difference of −1.5% (95% confidence interval [CI], −12 to 9.3; p = 0.8). Fragments with loss of orientation were 26% less frequent with ERBT (95% CI, −40 to −13; p < 0.001). Median thermal damage was 5.0% lower with ERBT (95% CI, −9.0 to −1.0; p < 0.001). The main limitation was the lack of standardised specimen-handling procedures across sites, leading to suboptimal preparation of some ERBT specimens. Conclusions and clinical implications T-stage concordance was similar between the ERBT and cTURBT groups. ERBT specimens showed improved orientation and reduced thermal damage. Standardised specimen-handling protocols are essential to fully realise the pathological advantages of ERBT.