Immunohistochemical expression of thymidine phosphorylase/platelet-derived endothelial cell growth factor in squamous cell carcinoma of the esophagus.

BACKGROUND/AIMS: Thymidine phosphorylase (dThdPase) is identical to platelet-derived endothelial cell growth factor which is an angiogenic factor. We attempted to clarify the significance of dThdPase expression in esophageal squamous cell carcinoma (SCC). METHODOLOGY: Tissues samples were taken from 50 patients with esophageal SCC after curative surgery. The expression of dThdPase was immunohistochemically examined using a monoclonal antibody to dThdPase (clone 654-1). Microvessels in SCC stained for Factor VIII-related antigen were counted. Vascular endothelial growth factor (VEGF) was immunostained with R11. Ki-67 antigen was immunostained with MIB-1, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate biotin nick end labeling was performed, and Ki-67 labeling index (LI) and apoptotic index were calculated. RESULTS: The expression of dThdPase was observed in 30 patients (60%). Between the SCC with and without dThdPase expression, significant differences were found in microvessel count (p < 0.001) and VEGF expression (p < 0.01), but not in Ki-67 LI and apoptotic index. With regard to the clinicopathologic factors, significant differences were observed in histologic venous invasion (p < 0.01) and lymph node metastasis (p < 0.05). Survival rate after surgery was better in the patients with dThdPase-negative SCC (p < 0.05), and distant organ metastasis after surgery was frequently observed in the patients with dThdPase-positive SCC (p < 0.05). CONCLUSIONS: These results suggest that dThdPase expression may be associated with angiogenic promotion and may be one of the prognostic factors in esophageal SCC.