Evaluation of renicapsular involvement in Stages I and II renal cell carcinoma from the morphological and prognostic point of view

Background: Prognostic factors are essential for predicting postsurgical outcome in renal cell cancer (RCC). This study aimed to evaluate the prognostic impact of renicapsular involvement (RCI; invasion without penetration) in Stage I (pT1N0M0) and Stage II (pT2N0M0) RCC and to histomorphologically compare the structure of fibrous tumoral capsule with the pattern of RCI, the differentiation of which might by challenging in localized RCCs spreading near the renicapsule.

Materials and methods: We retrospectively investigated a cohort of 635 study group patients (396 men and 239 women; mean age: 60.9 years; range: 18-84 years) in terms of histomorphology and clinical outcome after surgery (nephrectomy or elective nephron-sparing surgery) at Stages I and II RCC (pT1-2N0M0). In 489 patients who were still alive at the end of the study, median follow-up was 80 months (mean 86.1 months). Disease-free survival (DFS) was calculated using the Kaplan Meier method. Univariate and multivariate Cox proportional hazards regression models were fit to determine possible associations between various parameters and survival. Another 55 control group patients (38 men and 17 women) aged between 44 and 75 years (mean age 61.4 years) with pT3a RCC were analyzed for statistical comparison (mean and median follow-up of the survivors were 85.7 and 84 months).

Results: The 5-year DFS rate for patients with and without RCI was determined to be 76.9% and 86.3%, respectively (P < 0.01). Patients with histopathologically confirmed RCI appear to have the same adverse prognostic outcome as patients with RCC invading perinephric tissue (pT3aN0M0; P = 0.493). Histopathologically, fibrous tumoral capsule and RCI conventionally show a different morphology, making their separation straightforward.

Conclusions: RCI reflects adverse prognostic outcome in surgically treated Stages I and II RCC. It can be determined by the pathologist without additional expense in time and cost. Hence, clinical pathologists should render a clear statement concerning RCI when reporting on small localized RCC specimens in order to provide additional prognostic information in individual cases and to facilitate selection of appropriate patients to be included in further standardized prospective studies, which are required to confirm the prognostic impact of RCI in Stages I and II RCC.