Prognostic significance of erythropoietin expression in human renal cell carcinoma

OBJECTIVES: To investigate, in a retrospective study, the expression of erythropoietin (Epo) in human renal cell carcinoma (RCC) and its correlation with overall survival, as Epo (an haematopoietic cytokine that regulates the production of red blood cells), with its receptor, was recently localized in non-haematopoietic tissues, e.g. liver, uterus, central nervous system, vascular endothelial cells and solid tumours. PATIENTS AND METHODS: We used data from 113 patients who had radical nephrectomy for RCC between 1990 and 2000, taking sections from formalin-fixed and paraffin wax-embedded tissue blocks. The association between Epo staining and the patients' characteristics was assessed by either chi-squared tests (for categorical variables) or two-sample independent t-tests (for continuous variables). RESULTS: Tissue from 37 patients (33%) was positive for cytoplasmic Epo expression; 76 (67%) samples were negative. Univariate hazard ratio analysis confirmed that those with positive Epo staining were more than twice as likely to die as those with negative staining (hazard ratio 2.34, 95% confidence interval 1.27-4.3). CONCLUSION: This study shows that the expression of Epo in RCC is adversely associated with overall survival. This is the first report of such an association, and might be explained by the loss of Von Hippel-Lindau protein function in clear cell RCC. The expression of Epo might have potential use in clinical trials when stratifying high-risk patients for adjuvant therapy after nephrectomy.