Prognostic features of upstaged pT3a renal tumors with fat invasion after robot-assisted partial nephrectomy: is it time for a new subclassification?

The clinical management of pT3a pathologic-upstaged renal cell carcinoma (RCC) patients is actually controversial. Aim of this study was i) to assess the impact of pT3a upstaging on oncologic outcomes after robot-assisted partial nephrectomy (RAPN) for cT1-T2 RCC; ii) to explore clinical and surgical predictors of pT3a upstaging; iii) to evaluate the differential impact of perinephric fat invasion (PFI) or sinus fat invasion (SFI) on survival outcomes after RAPN in case of upstaged pT3a RCC.Clinical and surgical data from consecutive RCCs treated with RAPN in a single referral centre between January 2017 and June 2021 were prospectively collected and retrospectively reviewed. Pathological upstaging to pT3a tumors with fat invasion was further stratified in SFI or PFI. Uni- and multivariable analysis were fitted to explore clinical and surgical predictors of disease recurrence.Overall, 1852 patients were enrolled and 179 (9.7%) with pT3a upstaging were found. Median age was 65 (IQR 56-73) years with a median BMI of 25.6 (23.6-29.0). At a median follow up of 26 (9-38) months, 76 (4.1%) patients showed disease recurrence. Multivariable analysis confirmed PADUA score ≥10 (OR 1.76, CI 95% 1.18-1.91, p = 0.001), age at surgery (OR 1.04, CI 95% 1.01-1.06, p = 0.01), clinical tumor diameter (OR 1.31, CI 95% 1.17-1.47, p = 0.001), tumor necrosis (OR 1.54, CI 95% 1.08-1.88, p = 0.001) and nucleolar grading ≥3 (OR 1.27, CI 95% 1.01-1.44, p = 0.001) as independent predictors of pT3a upstaging. Multivariate Cox regression model showed pathological sinus fat invasion as an independent predictor of disease recurrence (HR 3.43, CI 95% 1.51-7.77, p = 0.003) in pT3a upstaged group.In pathologically upstaged pT3a RCCs, sinus fat invasion was confirmed as independent predictor of disease relapse. In this light, the definition of novel risk categories in the pT3a patients setting should be encouraged.