EAU 2021: Confederación Americana De Urología Lecture: What Is the Role of TUR in Muscle Invasive Bladder Cancer?

(UroToday.com) The 2021 European Association of Urology (EAU) Annual meeting’s Confederación Americana de Urología lecture was provided by Dr. Alejandro R. Rodriguez discussing the role of TUR in muscle invasive bladder cancer (MIBC). Dr. Rodriguez started by highlighting that bladder cancer is the 10^th most commonly diagnosed cancer worldwide with 573,000 new cases and 213,000 deaths. Bladder cancer is more common in men than in women with an incidence of 9.5 per 100,000 men, a mortality of 3.3 per 100,000 men, and approximately four times more common than women globally. Bladder cancer includes three categories that differ in terms of prognosis, management, and treatment aims specifically to non-muscle invasive disease, muscle invasive disease, and metastatic disease.

TUR for MIBC plays an important role in the clinical stage of the primary tumor, type of histology and disease grade (especially variant histology), and in bladder preservation options. With regards to staging, the depth of invasion is the most important determinant of prognosis and treatment of localized bladder cancer:

T2 (MIBC) – is defined by malignant extension into the detrusor muscle
T3 disease – defined by perivesical fat involvement
T4 disease – includes extravesical invasion into the surrounding organs, such as prostate stroma, seminal vesicles, uterus, vagina, pelvic sidewall, and the abdominal wall

A properly performed TURBT samples the underlying bladder wall including the muscularis propria. Understaging occurs with TURBT and it may result in missing muscle infiltration in up to 25% of invasive cancer. TURBT is operator-dependent, so residual tumor rates vary widely with experience. There is a need to emphasize the importance of experience, judgement, technique, and skill in carrying out a high quality TURBT.¹ Other technical options include en bloc resection, enhanced visualization, and the use of bipolar energy.

Recently, there has been interest in multiparametric MRI for bladder cancer, specifically the VI-RADS system. The rationale and aim of VI-RADS were to define a standardized approach to imaging and reporting mpMRI for bladder cancer, defining the risk of muscle invasion.² The scoring is applicable to untreated patients and to treated patients having only received a diagnostic TURBT, but prior to re-TURBT. mpMRI is best performed before or at least 2 weeks after TURBT, bladder biopsy, or intravesical treatment. MRI does not necessarily have the ability to visualize all of the histological bladder wall layers, however, it is able to assess size, location, multiplicity, and morphology. A 5-point VI-RADS score is generated using the individual T2W, DWI, and DCE MRI categories and suggests the probability of muscle invasion. The dominant sequences for risk estimates are DWI (first) and DCE (second, especially if DWI is sub-optimal). The T2 sequence (structural category) is helpful as a first pass guide.

The VI-RADS 1.0 scoring is as follows:

TUR is also important for delineating grade and histology of the tumor. The majority of MIBC cases are high-grade, but TUR is crucial for assessing variant histology and non-urothelial carcinoma (~10%) that may change treatment approaches to MIBC. A one treatment fits all approach for MIBC is a limiting factor, and patient stratification to guide treatment options may be achieved using molecular classifications. Understanding the biological role and therapy response is mandatory for clinical implementation. A recent consensus on the molecular classification of MIBC showed that among 1,750 MIBC transcriptome profiles there were six molecular classes: luminal papillary (24%), luminal nonspecified (8%), luminal unstable (15%), stroma-rich (15%), basal/squamous (35%), and neuroendocrine-like (3%).³ These subtypes are able to prognosticate overall survival:

When considering bladder preservation strategies, maximal TUR alone is crucial in management and is used concurrently with chemoradiotherapy. Optimal candidates for bladder sparing treatment are those with solitary lesions <2 cm in size, no associated CIS component, no palpable masses, and no hydronephrosis. All patients should undergo an aggressive re-resection of the site within 4 weeks of the primary procedure in order to ensure no residual disease is present.

Dr. Rodriguez concluded his presentation noting several summary statements:

The role of TUR in MIBC is to obtain tissue for histopathologic diagnosis, grading and clinical staging
In very selected patients, TUR alone may be a reasonable alternative to more invasive options
Maximal TUR with concurrent chemoradiotherapy is a primary treatment option for patients that desire bladder preservation as an alternative to radical cystectomy

Presented by: Alejandro R. Rodriguez, MD, Rochester General Hospital, Rochester, NY

Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Assistant Professor of Urology, Georgia Cancer Center, Augusta University/Medical College of Georgia, @zklaassen_md on Twitter during the 2021 European Association of Urology, EAU 2021- Virtual Meeting, July 8-12, 2021.

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