Angiogenesis in renal cell carcinoma: correlation of microvessel density and microvessel area with other prognostic factors

This study was aimed at evaluating the association between tumor vascularity and other known prognostic factors in different histopathological subtypes of renal cell carcinoma (RCC). In 41 cases of RCC, immunohistochemistry was performed using anti-CD34 antibody and Ki-67 (MIB-1). Microvessel density was estimated in an area of 0.23 mm² representative of the highest microvessel density (“hot spot”). The microvessel area (MVA) was expressed as percentage of total tumor area occupied by vessels. Endothelial proliferation index (EPI) was determined from sections stained by Ki-67. The relationship between MVD, MVA, EPI and prognostic parameters of RCC like stage, grade and tumor cells proliferation index (TPI) was evaluated. The tumor MVA increased significantly with the higher stage of the tumor (P < 0.001) and increase in TPI (P < 0.05). The MVD, however, did not show significant correlation with grade and stage of the tumor. Microvessel area appears to be a better prognostic marker for RCC when compared to microvessel density. The increase in MVA, without increase in MVD, with increasing stage may be due to the development of larger diameter vascular channels in higher-stage tumors, and this is thought to facilitate metastasis.