Location of extrarenal tumor extension does not impact survival of patients with pT3a renal cell carcinoma

Purpose: The current TNM classification for pathological pT3a renal cell carcinoma includes patients with perinephric or sinus fat invasion, suggesting that the prognoses are similar for these pathological findings. However, sinus fat invasion was proposed by some investigators to be an independent predictor of inferior cancer specific outcome following surgical treatment. To assess and improve the predictive ability of the current pT3a primary tumor classification we evaluated the prognostic significance of location of extrarenal. tumor extension on cancer specific survival following surgery. Materials and Methods: The database of 3,470 patients at our institution who were treated for renal cell carcinoma from 1990 to 2006 was searched for those with pT3a tumors managed by partial or radical nephrectomy. Patients with nonrenal cell carcinoma histology, direct adrenal invasion or a followup of less then 6 months were excluded from analyses. The prognostic importance of all clinical and pathological variables was investigated using Cox proportional hazards regression. Results: A total of 365 patients with pT3a renal cell carcinoma and a mean followup of 33.5 months (range 6.1 to 158.6) met study inclusion criteria and they comprise the data set for this analysis. There was no difference in 5-year cancer specific survival between 166 patients (45.5%) with SF invasion and 199 (54.5%) with PF invasion only (50.8% and 54.1%, p = 0.782 respectively). On univariate analyses neither sinus fat invasion nor the location of extrarenal extension, assessed as perinephric fat vs sinus fat vs perinephric plus sinus fat, correlated with cancer specific survival following surgical treatment (HR 1.052, p = 0.783 and HR 1.072, p = 0.543, respectively). After adjusting for the effects of nodal and systemic metastases tumor grade and sarcomatoid differentiation remained independent predictors of renal cell carcinoma specific survival in our pT3a cohort of patients (HR 1.508, p = 0.003 and HR 1.810, p = 0.018, respectively). Conclusions: In contrast to previously reported observations, in our cohort of surgically treated patients with pT3a renal cell carcinoma the location of extrarenal extension was not an important prognosticator of cancer specific mortality. Based on our findings we confirm that perinephric and/or sinus fat should be similarly subclassified in the primary tumor staging system.