The 7th TNM classification summarizes renal cell carcinoma (RCC) with perirenal (PFI) and/or sinus fat invasion (SFI) as well as hilar vein involvement (RVI) as pT3a tumors. In this study, we aimed to determine the prognostic value of fat invasion (FI) in the different compartments and RVI for medium-term cancer-specific-survival (CSS) in pT3a RCC.
Patients with pT3a RCC were identified using an institutional database. All original pathological reports were reclassified according to the 7th TNM edition. The prognostic value of FI as well as divided into PFI, SFI, combined PFI + SFI, and RVI for CSS was assessed using univariate and multivariate Cox-regression analysis. Survival was estimated using the Kaplan-Meier method.
Median follow-up in 184 pT3a tumors was 38 months. FI was detectable in 153 patients (32.7% PFI, 45.1% SFI, 22.2% PFI + SFI), 31 patients showed RVI alone. Combined PFI + SFI increased the risk of cancer-related death compared to PFI (HR 3.11, p < 0.01), SFI (HR 1.84, p = 0.023) or sole RVI (HR 2.12, p = 0.025). In multivariate analysis, a combined PFI + SFI vs. PFI or SFI as the only compartment involved was confirmed as independent prognostic factor (HR 1.83, p = 0.029). Patients with FI and simultaneous RVI had significantly shorter CSS (HR 2.63, p < 0.01). In an unweighted model, the difference between patients with combined PFI + SFI and RVI and those with PFI alone was highest (HR 4.01, p = 0.029).
These results underline the subdivision of pT3a RCC depending on the location of FI and RVI for patient stratification.