Stage pT3a of renal clear cell carcinoma: do tumors with sinus fat involvement behave the same as those with perinephric fat involvement?

Introduction: In this report, we review our series of patients with pT3a clear cell renal carcinoma (CCRC) and comment on their outcome. Materials and Methods: We have reviewed 260 cases of CCRC operated in the Mostoles General Hospital, Madrid, between 2000 and 2004. We have found 30 cases with pT3a tumors. Eleven of them were invading the perinephric fat, nine were invading the renal sinus fat and ten were pT3a locally but showed metastasis at the moment of diagnosis (cM1, TNM stage IV). We have analyzed the prognostic influence of histopathological parameters (vascular invasion, size, Fuhrman grade) and also immunohistochemical ones (p53, cyclin D1, proliferation index with Ki67, bcl-2 and vascular density with CD34). Results: Only six of 10 patients with perinephric fat involvement died of disease compared with all the patients with sinus fat involvement, suggesting a worse prognosis for the latter. However, this difference did not reach statistical significance, probably due to the small number of cases. Of all the clinical, histological and immunohistochemical factors analyzed, only cyclin D1 was a strong indicator of worse prognosis in pT3a CCRC (p=0.02). We could not show any statistically significant relation between vascular density and prognosis. Vascular invasion was the only histological parameter that showed a trend toward significance (p=0.09). Conclusions: Sinus fat involvement might be underestimated in some series. A protocol for nephrectomy specimen handling could improve the detection rate of sinus fat involvement and allow the performance of randomized prospective studies to determine whether these tumors behave similarly.