Microvascular density as an independent predictor of clinical outcome in renal cell carcinoma: An automated image analysis study

Tumor microvascular density (MVD) has been shown to correlate with the aggressiveness of several cancers. With the introduction of targeted anti-angiogenic therapy, assessment of MVD has the potential not only as a prognostic but also as a therapeutic marker. The significance of tumor vascularity in clear cell renal cell carcinoma (ccRCC) has been debated, with studies showing contradictory results. Previous studies were limited by manual quantification of MVD within a small area of tumor. Since then, the validity of this method has been questioned. To avoid the inaccuracies of manual quantification, we employed a computerized image analysis, which allowed assessment of large areas of tumor and adjacent normal tissue. The latter was used as an internal reference for normalization. MVD and vascular endothelial growth factor (VEGF) were assessed in 57 cases of ccRCC. Sections were immunostained for CD34 and VEGF. Areas of ccRCC and normal kidney medulla were analyzed within scanned images using software that counted CD34-positive vessels and measured the intensity of VEGF staining. We obtained unadjusted values from tumoral areas and calculated adjusted values as tumor/normal ratios. Unadjusted MVD had no association with clinical outcome. However, similarly to tumor stage, higher adjusted MVD was associated with shorter disease-free survival (log-rank P0.037, Cox P0.02). This was significant in univariate and multivariate analyses. MVD did not correlate with tumor stage, pointing to its independent prognostic value. As expected due to the known molecular abnormalities in ccRCC, most tumors showed higher VEGF expression than normal tissue. Higher adjusted VEGF was associated with high tumor grade (P0.049). The finding of increased MVD as an independent marker of tumor aggressiveness may prove useful in the development of new tests for prognostic and therapeutic guidance. Digital techniques can provide more accurate assessment of immunomarkers and may reveal less obvious associations. © 2012 USCAP, Inc All rights reserved

Assessment of the prognostic significance of endoglin (CD105) in clear cell renal cell carcinoma using automated image analysis

The behavior of clear cell renal cell carcinoma can be difficult to predict. Angiogenesis has proven to be a useful prognostic indicator in different malignancies. Endoglin (CD105) is a new marker of angiogenesis found to have prognostic utility in various tumors. Here, we provide the first automated digital assessment of intratumoral microvascular density in clear cell renal cell carcinoma using endoglin and CD31 and assess their utility as predictors of clinical outcome. Both endoglin and CD31 expression showed association with advanced tumor stage (P = .025 and P = .011, respectively). There was a significant correlation between CD31 and tumor grade (P = .034). Kaplan-Meier survival curves showed that patients with higher endoglin expression had significantly shorter progression-free survival (P = .010). Patients with higher CD31 expression tended to have a worse prognosis, although this was not statistically significant (P = .082). In univariate analysis using endoglin as a continuous variable, increased endoglin was strongly associated with reduced survival (hazard ratio, 1.74; 95% CI, 1.39-2.18; P = <.001). CD31 also correlated with poor outcomes (hazard ratio, 1.52; 95% CI, 1.24-1.86; P = .001). There was no correlation between CD31 and endoglin expression (r = -0.090, P = .541). Receiver operating characteristic analysis showed the area under the curve to be 0.749 for endoglin and 0.550 for CD31. In conclusion, increased endoglin and CD31 expression are associated with a higher tumor stage and decreased progression-free survival. Our automated approach overcomes many limitations of manual quantification. Advances in digital assessment of immunohistochemical markers can be helpful in standardizing the evaluation of tumor biomarkers. © 2012 Elsevier Inc. All rights reserved