Transurethral en bloc submucosal hydrodissection vs conventional resection for resection of non-muscle-invasive bladder cancer (HYBRIDBLUE): a randomised, multicentre trial.

Objective: To determine whether transurethral en bloc submucosal hydrodissection of bladder tumours (TUEB) improves the quality of the resection compared to conventional transurethral resection of bladder tumour (TURBT) in patients with non-muscle-invasive bladder cancer (NMIBC).

Patients And Methods: A randomised, multicentre trial (HYBRIDBLUE) was conducted with a superiority design. Six German academic centres participated between September 2012 and August 2015. Based on literature analysis, a sample size for accurate histopathological assessment concerning muscle invasion was assumed to be feasible in 50% (P = 0.5) of TURBT and 80% of TUEB cases. After pre-screening of a total of 305 patients, participants were allocated to two study arms: Group I: hexaminolevulinate (HAL)-guided TUEB; Group II: conventional HAL-guided TURBT. The primary endpoint was the proportion of specimens that could be reliably evaluated pathologically concerning muscle invasiveness. Secondary endpoints included rates of histopathological completeness of the resection, muscularis propria content, recurrence, and complication rates.

Results: A total of 115 patients (TUEB 56; TURBT 59) were eligible for final analysis. Adequate histopathological assessment, which included muscularis propria content and tumour margins (R0 vs R1), was present in 48/56 (86%) TUEB patients compared to 37/59 (63%; P = 0.006) in the TURBT group. R0 was confirmed in 30/56 TUEB patients (57%) and five of 59 TURBT patients (9%; P < 0.001). No complications of Grade ≥III were observed in both arms. At 3 and 12 months, three and 19 patients recurred in the TUEB group vs seven and 11 patients in the TURBT group, respectively (P = 0.33 and P = 0.08).

Conclusions: In this randomised study, TUEB was shown to be clinically safe regarding perioperative endpoints. An adequate histopathological assessment concerning muscle invasion was significantly better assessable in the TUEB arm compared to standard TURBT. This finding indicates the clinical potential for reducing the rate of early re-resections. Yet, a larger study with recurrence-free survival as the primary endpoint is needed to assess the oncological efficacy between both techniques.