Cohort Profile: VZNKUL-NMIBC Quality Indicators Program: A Flemish Prospective Cohort to Evaluate the Quality...

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).