Thymidine phosphorylase in human esophageal squamous cell carcinoma

BACKGROUND: Experimental evidence has shown that thymidine phosphorylase (dThdPase) is identical to platelet-derived endothelial cell growth factor (PD-ECGF) and has angiogenic activity. The enzymatic activity of dThdPase was needed for the angiogenesis by the enzyme. These observations were catalysts for the current study. METHODS: The authors examined retrospectively the expression of the angiogenic factor dThdPase in 163 primary esophageal squamous cell carcinomas and its association with angiogenesis and clinicopathologic findings. To determine whether dThdPase expression was a prognostic factor after adjustment for the established prognostic factors and microvessel count, the authors conducted a survival analysis using the Cox proportional hazards model. RESULTS: dThdPase was expressed significantly more frequently (P < 0.001) in esophageal carcinomas (83 of 163, 50.9%) than in adjacent nonneoplastic esophageal tissue samples (20 of 163, 12.3%). Microvessel counts were significantly higher (P < 0.001) in dThdPase positive carcinomas (18.3+/-6.2) than in dThdPase negative carcinomas (8.2+/-7.5). Significant correlations were observed between dThdPase expression and numerous clinicopathologic findings, including pT, pN, pM categories; lymphatic invasion; venous invasion; and residual tumors. Prognostic variables studied using a Cox hazard regression model confirmed that dThdPase expression was an independent prognostic factor in esophageal squamous cell carcinoma, although pN category was the best predictor of patient survival. CONCLUSIONS: This study indicated that in esophageal squamous cell carcinoma, dThdPase expression is associated with angiogenesis and is an unfavorable prognostic factor. These findings implied that the inhibition of dThdPase would improve the prognoses of some patients with dThdPase positive esophageal tumors.