Impact of several histopathological prognosticators and local tumour extension on oncological outcome in pT3b/c N0M0 renal cell carcinoma.

OBJECTIVE: To investigate the prognostic relevance of different histopathological features and local tumour extension in patients with pT3b/c N0M0 renal cell carcinoma (RCC), as recently new proposals of reclassifying tumour fat invasion in pT3b/c RCC have been made but the effect of other histopathological tumour characteristics and combinations thereof with tumour invasion has yet to be determined in these patients. PATIENTS AND METHODS: Between 1990 and 2006, 1943 patients underwent surgical treatment for renal tumours in our institution, of which 175 patients (8.7%) had pT3b/c RCC. After exclusion of 57 patients (32.6%) with lymph node and/or distant metastases at the time of diagnosis, 118 (67.4%) remained for retrospective analysis. Different histopathological features and local tumour extension were studied for their association with cancer-specific-survival (CSS) and progression-free-survival (PFS) by univariate and multivariate analyses. Histopathology was reviewed and revised according to the 2002 Tumour-Nodes-Metastasis (TNM) classification system by one pathologist (S.B.). CSS and PFS were estimated by the Kaplan-Meier method.
RESULTS: Follow-up data were obtained from 110 patients at a median (range) of 3.2 (0.3-16.1) years. In univariate analysis, microvascular invasion (MVI) and capsular invasion increased the risk of tumour progression by 2.05- and 2.72-times (P = 0.037 and P < 0.001). Overall, tumour fat invasion (TFI) and the presence of areas composed by cells with eosinophilic cytoplasm were associated with a higher risk of progression (P = 0.001 and P = 0.011) and reduced CSS (P = 0.037 and P = 0.017). In multivariate analysis, MVI and capsular invasion were associated with a two-fold increased risk of dying from cancer (hazard risk ratio, HR 2.22, P = 0.045 and HR 2.31, P = 0.011). TFI in general (P = 0.004) and specifically coexistent perirenal fat invasion (PFI) and renal sinus fat invasion (RSFI) were associated with a three-fold increased risk of developing tumour progression (HR 3.36, P = 0.001). The 10-year CSS and PFS rates were 39% and 36% for all patients, 47% and 45% for pT3b/c RCC with no PFI or RSFI, and 25% and 10% for PFI + RSFI.
CONCLUSION: Patients with pT3b/c RCC with MVI, capsular invasion, TFI and especially PFI + RSFI, have a markedly reduced prognosis compared with patients with pT3b/c RCC without these features. When these results are corroborated by additional studies and external validation, modification of the TNM classification system would be a sensible consequence.