Evaluation of individual and cumulative sites of extrarenal tumor invasion in pT3a clear cell renal cell carcinoma.

INTRODUCTION: The Tumor-Node-Metastasis classification of renal cell carcinoma (RCC) for pT3a tumors includes sinus fat invasion (SFI), perinephric fat invasion (PFI), renal vein invasion (RVI), and/or pelvicaliceal system invasion (PSI). The purpose of this study was to determine the association between these patterns of invasion (assessed individually and cumulatively) with the development of metastases and cancer-specific mortality (CSM). MATERIALS AND METHODS: We identified 160 patients who underwent radical nephrectomy for pT3a clear cell RCC between 2011 and 2017. The association between individual patterns of invasion and metastases and cancer-specific survival were evaluated with multivariate logistic regression. Cox Hazard proportion ratios and Kaplan-Meier survival curves were generated for patterns of invasion (assessed individually and cumulatively). RESULTS: The number of individual invasive patterns was as follows: 97/160 (61%) presented with RVI, 91/160 with SFI (57%), 62/160 with PFI (39%), and 24/160 (15%) with PSI. At multivariate analysis, both PFI and RVI were associated with metastases (P < 0.001 and 0.028, respectively). PFI (hazard ratio [HR] 4.12, 95% confidence interval [CI] 2.14-7.92; P < 0.001), RVI (HR 2.44, 95% CI 1.18-5.01; P = 0.015), SFI (HR 2.13, 95% CI 1.05-4.34; P = 0.036) had higher CSM, while PSI (HR 1.43, 95% CI 0.65-3.16; p = 0.38) did not show increased CSM. Furthermore, cumulative analysis showed that multiple invasive patterns resulted in worse CSM (p < 0.001). CONCLUSIONS: In our study, PFI was associated with the most aggressive behavior while PSI was the most indolent. Furthermore, the presence of more than one pattern of invasion was associated with worse CSM. These results indicate that reporting of the individual location and cumulative amount of pT3a patterns of invasion in clear cell RCC is clinically relevant.