Proposed tripartite classification of T1 renal cell carcinoma: Comparison with current binary system.

Objective: Outcomes of stage 1 renal cell carcinoma (RCC) are heterogeneous and vary widely. We sought to investigate whether tripartite reclassification of current binary T1 RCC would lead to more rational consolidation of similar outcomes that may improve predictive ability.

Methods: We performed a retrospective multicenter analysis of patients undergoing radical (RN) or partial nephrectomy (PN) for clinical T1N0M0 RCC. The cohort was divided into tumor size ≤3 cm, >3 cm or ≤5 cm, and >5 cm or ≤7 cm. Primary outcome was cancer-specific mortality/cancer-specific survival (CSM/CSS). Secondary outcomes were all-cause mortality/overall survival (ACM/OS) and recurrence/recurrence-free survival (recurrence/RFS). Multivariable analysis (MVA) was used to elucidate predictive factors for CSM, ACM, and recurrence. Kaplan-Meier Analysis (KMA) analyzed 10-year CSS, OS, and RFS. AUC/ROC analysis compared predictive capability of proposed tripartite reclassification of T1 defined as proposed-T1a (≤3 cm), T1b (>3 and ≤5 cm), and pT1c (>5 and ≤7 cm) vs. current binary T1a (≤4 cm) and T1b (>4 and ≤7 cm).

Results: 2,989 patients were analyzed (median follow-up 60 months). Increasing age (HR = 1.05, P < 0.001), proposed-T1c (vs. proposed-T1a referent [HR = 2.15, P = 0.008]), radical nephrectomy (HR 1.65, P = 0.023), and high-grade (HR = 2.44, P < 0.001) were associated with worsened CSM. Comparing proposed-T1a, T1b, and T1c, KMA revealed significantly worsened: 10-year OS with larger tumor size: (81% vs. 80% vs. 63%, respectively, P < 0.001) and 10-year CSS with larger tumor size (93% vs. 91% vs. 81%, respectively, P < 0.001). AUC analysis revealed greater predictive power for proposed-T1a, T1b, and T1c vs. current T1-RCC binary classification for OS (0.567 vs. 0.556) and CSS (0.643 vs. 0.599).

Conclusion: Proposed-Tripartite subclassification of T1 RCC into T1a, T1b, and T1c groups corresponds to distinctive populations whose biological potential aligns more closely and may enhance risk stratification, refine pretreatment counseling and postoperative follow-up compared to protocols based on current binary T1 classification.