Thymidine phosphorylase as a prognostic factor in renal cell carcinoma

The purpose of the current study was to clarify further the clinicopathologic significance of thymidine phosphorylase (TP) expression in renal cell carcinoma (RCC). TP expression was evaluated with immunohistochemistry assays using monoclonal anti-TP antibody in formalin-fixed, paraffin-embedded archived specimens of 70 patients with radically operated nonmetastatic RCC (M0 by TNM classification). Semiquantitative analysis, using a scoring system for staining pattern and staining intensity was used. Univariate analysis showed that the characteristics that carried the prognostic significance for survival were age as continuous characteristic (chi-square log-rank test P = 0.0121), TP expression (P = 0.0061), histologic grade (P < 0.0001), and stage (P = 0.0244). In multivariate analysis (by Cox proportional hazards regression analysis), the factors significant for survival were age (HR 1.09; 95% CI 1.03-1.14), stage (HR 2.76; 95% CI 1.27-6.07), and histologic grade (HR 7.91; 95% CI 2.11-29.7), TP did not show independent significant value (HR 0.68; 95% CI 0.19-2.50). However, TP had strong correlation with histologic grade (P = 0.818). In conclusion, TP expression level in RCC is strongly correlated with histologic grade, which is one of well-known prognostic factors in RCC, but TP had no independent prognostic value.