Retrospective Histopathological Aspects in the Recurrence of Bladder Tumors Following TUR‐B: Insights into Progression and Regression Patterns

Background: Bladder cancer is one of the most common urological neoplasms worldwide, often requiring multiple transurethral resections of the bladder (TUR-B) due to high recurrence rates. This retrospective study analyzes 389 histopathological (HP) reports from 117 patients to evaluate the evolution of malignancy grade (G1, G2, G3) and invasion level (non-invasive vs. invasive) in recurrent bladder tumors. Methods: We included patients who underwent ≥2 TUR-B interventions between 2009 and 2024, had complete HP data for each resection, and were followed to assess recurrence, progression, and regression. Descriptive statistics and chi-square tests were used to examine differences in tumor behavior among subgroups. Endpoints included recurrence (any new tumor), progression (increase in grade or stage to ≥T2), stagnation (no change in grade or stage), and regression (downgrade or downstage from invasive to non-invasive). Results: Nearly 15% of non-invasive tumors progressed to invasive disease, whereas over 30% of tumors initially classified as invasive showed partial or complete regression during subsequent resections. G2 tumors were most prevalent (around 55%), with more than half exhibiting stagnation. Some high-grade (G3) lesions demonstrated notable regression rates, highlighting possible responsiveness to intravesical therapy. Conclusions: These findings underscore the heterogeneity of bladder tumor evolution following TUR-B and the importance of vigilant surveillance and adjuvant therapies. While a subset of invasive tumors may regress, others progress despite initial low-grade presentation. Future prospective or multivariate analyses are needed to identify precise predictors of progression and regression in non-muscle-invasive bladder cancer (NMIBC).