Abstract Purpose To identify independent prognostic factors for recurrence and develop a practical risk stratification system in patients with clinical T1 (cT1) clear-cell renal cell carcinoma (ccRCC) following curative-intent surgery. Methods This retrospective multi-institutional study analyzed 1081 consecutive patients with cT1N0M0 ccRCC who underwent partial or radical nephrectomy at 14 Japanese tertiary centers (2016–21). We evaluated six established prognostic factors based on prior literature: pathological T3 upstaging, tumor size, nuclear grade, tumor necrosis, surgical approach, and venous invasion. Cox proportional hazards regression was performed to identify independent predictors of recurrence-free survival. Results During a median follow-up of 48 months, 66 patients (6.1%) developed recurrence. Multivariable Cox regression identified two independent prognostic factors: pathological T3 upstaging (HR 4.67, 95% CI 2.40–9.08, P .001) and tumor necrosis (HR 2.51, 95% CI 1.22–5.13, P = .012). Tumor size showed borderline significance (HR 1.22 per cm, 95% CI 1.00–1.49, P = .055). Based on the significant factors, patients were stratified into low-risk (91.1%, no upstaging/necrosis) and high-risk (8.9%, upstaging or necrosis present) groups with recurrence rates of 4.3% and 25.0%, respectively (log-rank P .001). The 5-year recurrence-free survival rates were 95.2% and 73.4% for low- and high-risk groups, respectively. Conclusions Pathological T3 upstaging and tumor necrosis were identified as the only independent predictors of recurrence in cT1 ccRCC. This simplified two-tier risk stratification effectively distinguishes a small high-risk subset (9% of patients) with 25% recurrence rate from the low-risk majority, enabling tailored surveillance strategies and appropriate selection for adjuvant therapy trials.
Ueki et al. (Mon,) studied this question.