Cohort Profile: VZNKUL–NMIBC Quality Indicators Program: A Flemish Prospective Cohort to Evaluate the Quality Indicators in the Treatment of Non-Muscle-Invasive Bladder Cancer
Authors: Akand Murat , Veys Ralf , Ost Dieter , Vander Eeckt Kathy , Baekelandt Frederic , Van Reusel Raf , Mattelaer Pieter , Baekelandt Loic , Van Cleynenbreugel Ben , Joniau Steven , Van der Aa Frank 
Published: October 2024

Purpose: Bladder cancer (BC) is a heterogeneous disease with varying outcomes, influenced by disease heterogeneity and variability in treatment and follow-up. Risk groups have been established for non–muscle-invasive BC (NMIBC) to standardize therapy, and several quality control indicators (QCIs) monitor adherence to these risk group-based guidelines. However, controversial results had been obtained regarding the oncological benefits of these QCIs until recent high-quality studies from large registries showed their usefulness. To improve adherence to the European Association of Urology (EAU) Guidelines and benchmark current care in Flemish hospitals within Vlaams Ziekenhuisnetwerk–KU Leuven (VZNKUL), a QCI program for NMIBC was initiated in 2013. This study aims to describe the demographic, clinical, and treatment data of patients enrolled in this program. Participants: The VZNKUL–NMIBC Quality Indicators Program Registry is a prospective cohort including patients treated and followed up with at seven academic and non-academic Flemish hospitals since June 2013. Data collection includes patient characteristics, tumor data, treatment, and oncological outcomes. Findings to date: From June 2013 to December 2020, 4744 transurethral resections of bladder tumors (TURBTs) from 2237 unique patients were analyzed. Most patients (80%) were men with a median age of 73. The median time from diagnosis to TURBT was 19 days. A single tumor was detected in 37% of TURBTs. Tumors larger than 3 cm were found in 20.8% of cases. In 46% of TURBTs, a reTURBT was scheduled according to guidelines. The complication rates were 7.5% and 2.4% for bladder perforation and bleeding, respectively. Postoperative single intravesical instillation of chemotherapy (SIVIC) was administered to 56.9% of 1533 indicated patients with a median time to administration of 4.7 h. Among the cohort, 60.4% had NMIBC, and 9.3% had muscle-invasive BC. Of 972 high-risk patients, 60.7% received adequate BCG induction, while 39.4% received adequate maintenance. After BCG induction ± maintenance, 39.7% were tumor-free, with 17.7% recurrence and 4% progression to muscle-invasive BC. BCG treatment was terminated early for 17% of patients due to intolerance. Early cystectomy was performed for 2.4% of the BCG-naïve patients, and 27.7% of patients with BCG failure underwent a BCG rechallenge. For intermediate-risk patients, 2.1% received adequate BCG, and 23% received intravesical chemotherapy. The median follow-up was 57 months. Five-year recurrence-free, progression-free, cancer-free, overall, and cancer-specific survival rates were 53%, 91.6%, 89%, 70.6%, and 95.6%, respectively, for the NMIBC patients. Of 400 non-metastatic MIBC patients, 217 (54.3%) underwent radical cystectomy (RC), of whom 46% received neoadjuvant chemotherapy, while 18 (4.5%) refused RC, and 74 (18.5%) were considered unfit for the surgery. Future plans: The VZNKUL–NMIBC Quality Indicators Program Registry will continue collecting data to evaluate QCIs and monitor treatment quality, enabling hospitals to benchmark their performance and improve patient care. Additionally, the registry’s real-world data can support research and international collaboration. Trial registration: The study was registered on ClinicalTrials.gov (NCT04167332).