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.