Clinicopathological analysis of recurrence and progression of low-grade papillary urothelial carcinoma of the urinary bladder: Predicting the outcome

Background: Urothelial carcinoma of the urinary bladder is the most common malignancy of the urinary system. Patients with low grade papillary urothelial carcinoma (LGPUC) usually have a low risk for tumor recurrence and progression; yet a subset of patients develop recurrence or grade/stage progression to high-grade papillary urothelial carcinoma (HGPUC). The clinicopathological and molecular factors that contribute to this progression are yet to be determined.

Objectives: In our study, we aimed to assess the incidence and clinicopathological factors associated with tumor recurrence/progression of LGPUC.

Methods: Using a pathological database of surgical specimens from patients who underwent bladder biopsies and/or transurethral resection of bladder tumors (TURBTs) between August 01, 2011, and July 31, 2021, at a large academic medical center, a single-center retrospective cohort analysis was performed, and medical charts of patients were reviewed.

Results: Of the total 258 patients included, 157 (60.9 %) had "no recurrence", 85 (32.9 %) had ≥1 "recurrence of LGPUC", and 16 (6.2 %) had "grade progression to HGPUC". The mean follow-up time was 31.5 ± 32 months. Patients with "grade progression" and "recurrence of LGPUC" had larger mean tumor size on initial biopsy and multiple lesions on initial cystoscopy compared to those with "no recurrence." Interestingly, former smokers had 2.5- and 8.5-times higher risk of recurrence of LGPUC and grade progression, respectively.

Conclusion: Since the majority of our patients did not develop recurrence, we question whether there is tendency to overclassify the papillomas as LGPUC based on the 2004 WHO/ISUP consensus grading classification.