Prospective Validation of the ROL System in Substaging Pt1 High-Grade Bladder Cancer: Results from a Prospective Mono-Institutional Confirmatory Analysis in BCG Treated Patients

Patients with pT1 high-grade (HG) bladder cancer (BC) and a very high risk of progression might benefit from immediate radical cystectomy (RC), but this option remains controversial. Validation of a standardized method to evaluate the extent of lamina propria (LP) invasion (with recognized prognostic value) in transurethral resections (TURBT) specimens is still needed. The Rete Oncologica Lombarda (ROL) system showed a high predictive value for progression after TURBT in recent retrospective studies. Our aim was to validate ROL system on a large mono-institutional prospective series of primary urothelial carcinomas. From 2016 to 2020, we adopted ROL for all patients with pT1 HG BC on TURBT. We employed a 1.0-mm threshold to stratify tumors in ROL1 and ROL2. A total of 222 pT1HGBC were analyzed. Median age was 74 years, with male predominance (73.8%). ROL was feasible in all cases: 91 cases were ROL1 (41%) and 131 ROL2 (59%). At a median follow up of 26.9 months (IQR 13.8-40.6), we registered 80 recurrences and 40 progressions. ROL was a significant predictor of tumor progression at both univariable (HR 3.53; CI 95% 1.56 – 7.99; p<0.01) and multivariable (HR 2.90; CI 95% 1.25 – 6.75; p=0.01) Cox regression analyses. At Kaplan-Meier estimates, ROL showed correlation with both PFS (p=0.0012) and RFS (p=0.0167). Our results confirmed the strong predictive value of ROL for progression on a large prospective series. We encourage the application of ROL for reporting the extent of LP invasion, substaging T1 HG BC, and improving risk tables for urological decision making.