Extended cancer registry data for real-world evidence in bladder cancer: an update on the Prospective Bladder Cancer Infrastructure.

BACKGROUND: To advance clinical research and innovation in bladder cancer care, the Dutch Prospective Bladder Cancer Infrastructure (ProBCI) was established as a nationwide platform and has now been operational for 5 years. MATERIALS AND METHODS: ProBCI is a population-based cohort including all patients diagnosed since 2020 with high-risk non-muscle-invasive bladder cancer (HR-NMIBC), muscle-invasive bladder cancer (MIBC), or metastatic bladder cancer (mBC) in the Netherlands, comprising a Full and an Active Cohort. The full cohort includes all eligible patients, from whom core (HR-NMIBC and MIBC) or extended (mBC) clinical data and follow-up are collected within the Netherlands Cancer Registry (NCR). The active cohort is a subset of the full cohort and consists of patients who provided informed consent for additional collection of patient-reported outcomes and biomaterials alongside detailed clinical data and follow-up until death. RESULTS: As of 1 January 2026, the ProBCI full cohort comprised 20 737 patients. A growing number of participating hospitals (now 24) have been prospectively recruiting patients in the active cohort, with 1519 patients included to date. Among these, 73% completed baseline questionnaires (optional component) and 91% provided blood samples. Data from both cohorts are used by various studies including population characterizations, biomarker validation, and as concurrent control groups for single-arm trials. CONCLUSIONS: ProBCI has evolved into a uniquely positioned research infrastructure, with data collection embedded in the NCR, providing high-quality, high-granularity data and biomaterials to address diverse research questions. ProBCI demonstrates that nationwide collaboration can generate high-quality resources that support bladder cancer research and contribute to future improvements in patient outcomes.