Perinephric invasion as a prognostic factor in non-metastatic renal cell carcinoma: analysis of a nation-wide registry program

Objectives: Perinephric fat invasion (PFI) of renal cell carcinoma (RCC) is known to be associated with adverse pathological features and poor prognosis. We analyzed these associations using a sub-group of the RCC registry of The Cancer Registration Committee of the Japanese Urological Association. Methods: The study cohort of 2998 non-metastatic cases was retrieved from RCC registry (3648 in total). We compared clinicopathological characteristics of cases with PFI (n = 256) and without PFI (n = 2742), and investigated the impact of PFI on cancer-specific survival using univariate and multivariate analyses. Results: Compared with non-PFI cases, PFI cases were older (P = 0.003), and more likely to be hypertensive (P = 0.034) and symptomatic at presentation (P < 0.001). PFI tumors were larger (P < 0.001), and more often have sarcomatoid component (P < 0.001) and tumor thrombus (P < 0.001). Cancer-specific survival was significantly shorter in cases with PFI than without (P < 0.001). The difference in survival tended to be greater in cases with large tumors but was significant in small tumor sub-groups. Cancer-specific survival was significantly shorter in cases with both PFI and renal vein involvement (RVI) in comparison to those with PFI or RVI alone (P = 0.011, P = 0.007, respectively). On multivariate analysis PFI with and without sinus fat invasion remained as an independent risk factor along with symptom at presentation, low body mass index, hypertension, multiple tumors, large tumor size (>7.0 cm), sarcomatoid component and RVI. Conclusions: PFI was associated with advanced age and aggressive pathological features. PFI is an independent prognostic factor in non-metastatic RCC.