Use of monopolar versus bipolar transurethral resection in non-muscle-invasive bladder tumors related to thermal artifact and recurrence and progression rates

Abstract

BACKGROUND: Bladder cancer is the 10th most common malignant tumor worldwide. 75% of cases are diagnosed at a non-muscle-invasive stage, 90% being of urothelial origin. The management of non-muscle-invasive bladder tumors is based on transurethral resection and the application of adjuvant intravesical therapy. Their main drawback is that they have a high recurrence rate and may progress to a more advanced stage. It exists two main modalities of transurethral resection: monopolar (gold standard) and bipolar systems. The last one has proven to have significant advantages over monopolar energy, such as reducing the presence of thermal artifact in tissue samples, which may interfere in the pathological diagnosis, the basis for the management of these patients. However, there is still controversy about if this reduction have a significant impact on the histological analysis. The recurrence and progression rates decrease with the intravesical therapy, but there are no consistent studies that have evaluated the impact of using one modality of resection or another on these rates. OBJETIVE: to demonstrate that the use of bipolar transurethral resection in bladder urothelial carcinomas (non-muscle-invasive) reduce the presence of thermal artifact in tissue samples, allowing a proper pathological diagnosis and, consequently, a decrease in the recurrence and progression rates, in comparison to the use of monopolar systems. DESIGN: It will be a multicenter, longitudinal, prospective, parallel-group, double-blind, randomized and controlled clinical trial carried out in 4 hospitals of Cataluña. METHODS: Study subjects will be those newly diagnosed of bladder papillary tumors highly suspicious of urothelial carcinoma. They will be classified in 2 groups (as negative or positive cytology) and these will be randomized in 2 groups of intervention (undergo bipolar or monopolar transurethral resection). The pathologist will analyze the thermal artifact and other parameters. The patients will be classified in 3 risk groups (low, intermediate, and high), treated and followed-up for 1 year to evaluate the percentage of recurrence and progression. The sample size will be about 850 patients and recruitment of patients will last 15 months