Laser Versus Electrical Transurethral Enbloc Resection of Non-muscle Invasive Bladder Tumours: A Randomized Trial

INTRODUCTION

TURBT [transurethral resection of bladder tumor] constitutes a crucial procedure in the diagnosis and treatment of bladder cancer. A complete resection should be achieved either in fractions in bigger, or en-bloc in smaller tumours. The incise and scattering technique is against all oncological principles, damage caused by heat and fragmentation of the tumour hampers histological processing. The technique of resection in fractions ignores the parameter of negative surgical margins, theoretically, liberating tumour cells into the irrigation fluid, which facilitates their implantation and early recurrence. Furthermore, pathological staging may be impaired.

The absence of lamina muscularis propria (LMP, detrusor muscle, DM) in the specimen is associated with a higher risk of residual disease and early recurrence. Absence of LMP is also associated with lower surgical experience. The frequency of detecting MIBC in the second resection in initial pT1 ranges from 4 to 25%, and increases to 45% when no LMP was present. European guidelines 2018, stated that, En-bloc resection using monopolar or bipolar current, Thulium-YAG or Holmium-YAG laser is feasible in selected exophytic tumours. It provides high quality resected specimens with the presence of detrusor muscle in 96-100% of cases.

Recently, Martin-Doyle et al in the large analysis of 15,215 patients to assess recurrence, progression, and cancer-specific survival (CSS) from 73 studies, the highest impact risk factor was depth of invasion (T1b/c) into lamina propria (progression: [HR], 3.34; P < .001; cancer-specific survival: HR, 2.02; P = .001). Other previously proposed factors also predicted progression and CSS (lymphovascular invasion (LVI), associated CIS, non-use of bacillus Calmette-Guérin (BCG), tumor size > 3 cm, and older age; HRs for progression between 1.32 and 2.88, P ≤ .002; HRs for CSS between 1.28 and 2.08, P ≤ .02).

2018 EUA guidelines stated that, the depth and extent of invasion into the lamina propria (T1 substaging) has been demonstrated to be of prognostic value in retrospective cohort studies (LE: 3). Its use is recommended by the most recent 2016 World Health Organization (WHO) classification. However, the optimal system to substage T1 remains to be defined (Babjuk et al., 2018). These difficulty may be attributed to muscularis mucosa is only identified in 15% to 80% of bladder biopsy specimens, though its presence in 90% of radical cystectomy specimens (Wood, 2012). We have hypothesis that enbloc resection can get muscularis mucosa rate similar to radical cystectomy specimens rate.