En Bloc Versus Conventional Transurethral Resection of Bladder Tumors

Transurethral resection of bladder tumor (TURBT) remains the standard of care for diagnosis and staging of bladder cancers. Although the surgery is often considered a basic urologic procedure, there often are drastic differences in quality of resection and staging.^1,2 This discordance speaks to the significant technical demands of performing the procedure properly and adequately: without obtaining muscularis propria (MP) in the specimen, one cannot ensure adequate depth of resection. This critical depth of resection is paramount to proper clinical staging, as it is part of what classifies a patient’s risk stratification and subsequent treatment options and needs.

An Overview of TURBT

Absence of MP from TURBT specimens has been reported in up to 35% of cases.³ Classically, TURBT is performed by resecting the tumor piece by piece, eventually resecting the tumor at its base, where there may be muscle invasion. However, there are theoretical concerns with this technique, namely the loss of tumor integrity and concern for possible tumor seeding within the bladder. Because of this, there has been a recent push toward “en bloc resection” TURBT, wherein the bladder tumor is resected away from the bladder wall in its entirety. This type of resection aims to obtain tissue comprising both its exophytic and endophytic parts, which reduces tumor cell dispersion, allows precise resection, facilitates detrusor muscle (DM) sampling in proximity to the tumor base, and yields a more informative pathological specimen. Several retrospective studies have suggested there is benefit to en bloc resection, although there has not yet been a prospective study.

A recent report by Gallioli et al published in European Urology Oncology sought to provide the highest level of evidence to date, comparing en bloc TURBT to conventional TURBT, via a prospective randomized control trial.⁴ Investigators consisted of 7 senior urologic oncologists and 4 junior urologic oncologists (<5 years’ experience) at a single center who prospectively randomized 300 patients with bladder tumors <3 cm, with R3 tumors, without evidence of ureteral disease, and no evidence of muscle-invasive bladder cancer (MIBC). The study was designed as a noninferiority study, to evaluate a multitude of perioperative and clinical outcomes. The procedure was performed with monopolar or bipolar energy for both classic or en bloc TURBT, or in the case of en bloc resection, a thulium laser was also used for resection in some cases.

Findings of the Report

The only significant finding from the analysis was the ability to pathologically substage pT1 tumors, with all en bloc resections able to be substaged, whereas only 80% of classic TURBTs were able to be substaged. T1 substaging is defined as T1a (tumor invasion into the lamina propria without infiltration into the muscularis mucosa) and T1b (tumor invasion into the lamina propria, with infiltration of the muscularis mucosa).⁵ That is, the ability to differentiate a tumor’s invasion into the muscularis mucosa (as opposed to pT2 invasion into the MP) was found to be significantly improved with en bloc resection.

There was no difference between the classic approach compared with en bloc resection in terms of the length of catheterization or irrigation time, median length of hospitalization, planned adjuvant treatment, experiencing obturator reflex during resection, or complication rate. Notably, 5 of the 6 patients randomized to en bloc resection who ultimately underwent classic resection had anterior tumors that were not amenable to en bloc resection.

With a median follow-up of 15 months, there was no survival difference between either group. In what is thought to be the first prospective randomized control trial comparing classic TURBT to en bloc TURBT, Gallioli et al did not find many differences between the 2 study groups, demonstrating noninferiority of en bloc TURBT compared to classic TURBT. However, the one difference between the groups found to be statistically significant was the ability to better substage T1 disease via en bloc resection than by classic resection. While only a single significant data point, it is of crucial importance, as numerous studies have demonstrated meaningful differences in survival prognostics based on T1 substaging.^6,7 Although the data did not show a survival advantage, it should be noted that the follow-up was relatively small in the setting of smaller, mostly low-risk bladder tumors. Otherwise, the benefit of one approach compared with the other remains controversial.

There are reports within the literature demonstrating conflicting perioperative advantages with either approach. The data from these retrospective studies, when combined with the outcomes from what is thought to be the first prospective study evaluating the difference between these 2 approaches, help to further solidify that outside of the ability to substage T1 disease, there is little difference between classic and en bloc TURBT. Thus, with either approach, it is important to stress the importance of the fundamental principles of bladder tumor resection: one must clear all visible disease, resect to the level of the MP, and avoid perforation. When the operative surgeon adheres to these foundational principles, the choice of one approach over the other is likely to be of little consequence.

Daniel Tennenbaum, MD, is a urology resident at Maimonides Medical Center in Brooklyn, NY. His interests include surgical education and GU oncology with a focus on pediatric malignancies.

References

1. Gontero P, Sylvester R, Pisano F, et al. The impact of re-transurethral resection on clinical outcomes in a large multicentre cohort of patients with T1 high-grade/Grade 3 bladder cancer treated with bacille Calmette-Guérin. BJU Int. 2016;118(1):44-52. doi: 10.1111/bju.13354
2. Sfakianos JP, Kim PH, Hakimi AA, Herr HW. The effect of restaging transurethral resection on recurrence and progression rates in patients with nonmuscle invasive bladder cancer treated with intravesical bacillus Calmette-Guérin. J Urol. 2014;191(2):341-345. doi: 10.1016/j.juro.2013.08.022
3. Mariappan P, Zachou A, Grigor KM; for the Edinburgh Uro-Oncology Group. Detrusor muscle in the first, apparently complete transurethral resection of bladder tumour specimen is a surrogate marker of resection quality, predicts risk of early recurrence, and is dependent on operator experience. Eur Urol. 2010;57(5):843-849. doi: 10.1016/j. eururo.2009.05.047
4. Gallioli A, Diana P, Fontana M, et al. En Bloc versus conventional transurethral resection of bladder tumors: a single-center prospective randomized noninferiority trial. Eur Urol Oncol. 2022:S2588-9311(22)00068-2. doi: 10.1016/j.euo.2022.05.001
5. Turan T, Efiloğlu Ö, Günaydin B, et al. Comparative differences between T1a/b and T1e/m as substages in T1 urothelial carcinoma of the bladder. Int Braz J Urol. 2018;44(2):267- 272. doi: 10.1590/S1677-5538.IBJU.2017.0424
6. van Rhijn BW, van der Kwast TH, Alkhateeb SS, et al. A new and highly prognostic system to discern T1 bladder cancer substage. Eur Urol. 2012;61(2):378-384. doi: 10.1016/j. eururo.2011.10.026
7. Orsola A, Trias I, Raventós CX, et al. Initial high-grade T1 urothelial cell carcinoma: feasibility and prognostic significance of lamina propria invasion microstaging (T1a/b/c) in BCG-treated and BCG-non-treated patients. Eur Urol. 2005;48(2):231-238; discussion 238. doi: 10.1016/j.eururo.2005.04.013