PD07-02 DIVIDING PATHOLOGICALLY UPSTAGED T3A RENAL CELL CARCINOMA BASED ON CLINICAL T STAGE AT PRESENTATION IS ASSOCIATED WITH IMPROVED ALIGNMENT OF OUTCOMES: A CALL FOR TNM REVISION

INTRODUCTION AND OBJECTIVES: Pathological upstaged pT3a for Renal Cell Carcinoma (RCC) may have a wide variance in outcomes. We sought to redefine and reclassify pT3a RCC. We investigated recurrence and survival outcomes in pT3a disease and aimed to better categorize this cohort for improvement on current TMN staging. METHODS: Multicenter retrospective analysis of patients with cT1-3aN0M0 RCC who underwent radical or partial nephrectomy. After comparison of outcomes between pT1, pT2 and pT3a, patients were substratified within the pT3a category based on presenting clinical stage. Survival outcomes in T3a RCC were compared based on initial presenting clinical T stage. Comparison was drawn between pT1, pT2 and the subdivided pT3a group (cT1→pT3a, cT2→pT3a, and cT3a→pT3a). Primary outcome was recurrence free survival (RFS). Secondary outcome was overall survival (OS). Multivariable (MVA) and Kaplan-Meier (KM) analysis were conducted to elucidate risk factors and outcomes. RESULTS: We analyzed 2573 patients (1223 RN/1350 PN, median follow up 50.8 months). On MVA, higher clinical stage was a proportionally increasing predictor for risk of upstaging [compared to cT1a, OR of upstaging for cT1b, cT2a and cT2b was 2.6, 6.5, and 14.1, p<0.001] and recurrence [compared to cT1a upstaged to pT3a, HR for cT1b, cT2a, and cT2b upstaged to pT3a was 1.04 (p=0.912), 2.59 (p=0.008), and 2.7 (p=0.009)]. With regards to RFS, when pT3a was subdivided based on presenting clinical stage, significant differences in RFS emerged which aligned differently. Compared to 5 year RFS of pT1 (94.4%), cT1→pT3a aligned with pT2 (76.6% and 81.2%, p=0.346) while cT2→pT3a aligned with cT3a→pT3a 47.4% and 44.0%, p=0.815). With regards to OS, a similar alignment was noted for 5 year OS after subdivision, where pT1 was 89.9%, while cT1→pT3a correlated with pT2 (79.8% and 83.1%, p=0.640) and cT2→pT3a correlated with cT3a→pT3a 67.0% and 64.2%; p=0.893). CONCLUSIONS: Risk of upstaging to pT3a disease and subsequent recurrence is proportional to clinical stage at presentation. Patients with cT1→pT3a have outcomes more similar to pT2, while patients with cT2→pT3a align more closely to cT3a→pT3a. Future refinements of the TNM staging system for RCC should consider re-grouping cT1→pT3a into the pT2 group. Figure. No caption available. Source of Funding: Stephen Weissman Kidney Cancer Research Fund