CD44 is an independent prognostic factor in conventional renal cell carcinomas

Purpose: CD44 is a transmembrane glycoprotein involved in cell-cell and cell-matrix interactions. De novo expression of CD44 and its variant isoforms has been associated with aggressive behavior in various tumors. Since few data are available concerning the role of CD44 in the biological behavior of locally confined renal tumors, we analyzed the expression of CD44 in a large set of conventional renal cell carcinomas to determine its prognostic value in association with other clinicopathologic variables. Materials and Methods: Ninety-one patients with locally confined conventional renal cell carcinomas were studied. CD44 standard form (CD44H) and v6 isoform expressions were semiquantitatively evaluated on paraffin-embedded tumor tissue by immunohistochemistry. The prognostic value of the usual clinicopathological variables and CD44 expression was tested using Kaplan-Meier plots by the log rank test and Cox multiple hazard regression analysis. Results: Mo immunostaining was observed in normal renal tissue. Thirty-two of the 66 conventional renal cell carcinomas (48%) showed CD44H membranous staining of the tumor cells. Only 2 cancers displayed CD44v6 immunostaining. Among the different clinicopathological variables analyzed, tumor stage (p = 0.001), nuclear grade (p = 0.01), size (p = 0.02), vascular (p = 0.05) and perirenal adipose tissue invasion (p = 0.005), and CD44H expression (p = 0.01) were found to be significant prognostic parameters for survival using univariate analysis; Moreover, multivariate analysis indicated stage, nuclear grade and CD44 expression as independent prognostic factors both for overall and disease-free survival. Conclusion: CD44 can be considered as a useful prognostic parameter in conventional renal cell carcinoma and may be used in evaluation of the outcome of these tumors.