Over expression of clusterin is an independent prognostic factor for nonpapillary renal cell carcinoma

Purpose: Recent studies have revealed the powerful anti-apoptotic activity of clusterin in several types of malignant tumors. However, the significance of clusterin expression in human renal cell carcinoma has not been well characterized. We determined whether the expression level of clusterin in nonpapillary renal cell carcinoma may be used as predictor of tumor progression and prognosis. Materials and Methods: Total RNA was extracted from 93 nonpapillary renal cell carcinomas obtained at surgery and expression levels of clusterin messenger (m)RNA in these specimens were measured by Northern blot analysis. Findings were analyzed with respect to several clinicopathological factors. Results: There were 48 cases (52%) with strong clusterin mRNA expression and 45 (48%) in which it was weak or nonexistent. The expression level of clusterin mRNA did not significantly correlate with patient gender, age, tumor grade or size, or histological cell type, whereas pathological stage and the incidence of tumor recurrence were closely associated with clusterin expression (p <0.005 and <0.01, respectively). The recurrence-free and overall survival rates in patients with strong clusterin expression were significantly lower than in those with weak or no expression (p <0.05). Furthermore, multivariate analyses revealed that strong expression of clusterin was an independent predictor of tumor recurrence and overall survival (p <0.05). Conclusions: These findings suggest that the over expression of clusterin may be a useful prognostic parameter in patients with nonpapillary renal cell carcinoma after radical nephrectomy.