Purpose: We defined the prognostic role of tumor necrosis and its extent in nonmetastatic clear cell renal cell carcinoma. Also, we further investigated its pathogenesis by correlating this tumor feature with other pathological characteristics and molecular markers related to the von Hippel Lindau-hypoxia inducible factor pathway and to tumor proliferation.
Materials and methods: A total of 213 patients with nonmetastatic clear cell renal cell carcinoma were evaluated. Mean followup was 66 months. The presence and extent of histological necrosis were correlated with clinicopathological factors, Ki-67 antigen expression calculated by the MIB-1 (Ki-67 antibody) index, pVHL, HIF-1alpha, the tumor infiltrating lymphocyte subset and cancer specific survival.
Results: Histological necrosis was present in 63.8% of clear cell renal cell carcinoma cases. Necrosis was significantly associated with grade and the degree of tumor infiltrating lymphocytes, while its extent correlated significantly with grade, the degree of tumor infiltrating lymphocytes and stage. Tumor necrosis was a significant prognostic factor, which was confirmed even when limiting analysis to patients with intracapsular renal cell carcinoma. On multivariate analysis histological necrosis was not an independent predictor of cancer specific survival. The extent of tumor necrosis was not a significant prognostic factor. The presence and extent of histological necrosis was not associated with high Ki-67 expression and it did not correlate with pVHL expression or with nuclear and cytoplasmic HIF-1alpha expression.
Conclusions: Based on our results we cannot support histological necrosis and its extent as prognostic factors for clear cell renal cell carcinoma. Efforts should be made to develop nomograms that use routinely available and objective predictor variables. The precise mechanism that causes tumor necrosis remains unknown but the host immune response might significantly contribute to its development.