No prognostic marker for predicting recurrence in primary superficial bladder cancer has been established. The aim of this study was to investigate the expression levels of thymidine phosphorylase (TP) by enzyme-linked immunosorbent assay (ELISA) and the immunohistological localization of TP in primary superficial bladder cancer tissue to assess its association with tumor recurrence and stage progression as well as the pathological parameters of the tumor. TP expression in cancer tissues from 77 patients was measured by sandwich-type ELISA. Clinicopathological factors and the clinical prognosis were examined in relation to the expression levels of TP. To clarify the clinicopathological implication of TP localization in primary superficial bladder cancer tissue, the immunohistochemically determined TP expression was assessed for histological grades 1-3. The TP expression in primary superficial bladder cancer significantly increased with the histological grade and stage. The TP expression in patients with a shift to invasive cancer was significantly higher than in those without invasive cancer. Patients with low TP expression had a significant longer postoperative tumor-free period than those with high TP expression (P=0.011). High TP expression was an independent prognostic factor for tumor recurrence (P=0.0441). Strong immunoreactivity for TP was observed in the cytoplasms of tumor cells and vascular endothelial cells. This study suggests that elevated TP expression may be a prognostic marker for predicting recurrence in primary superficial bladder cancer, and that high TP expression may be associated with the marked proliferation of tumor cells and increased vascular endothelial cells, showing strong immunoreactivity for TP.

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