Role of tumor angiogenesis in gallbladder carcinoma: with special reference to thymidine phosphorylase

Background. Angiogenesis plays an important role in tumor growth and metastasis. Thymidine phosphorylase (TP), as well as vascular endothelial growth factor (VEGF), is known to be an angiogenic factor. The aim of this study was to clarify whether TP regulates angiogenesis and to determine the clinicopathological role of TP expression in gallbladder cancer. Methods. Thirty-seven patients with gallbladder cancer who underwent curative surgical resection were included in this study, and we evaluated results in 21 of these patients in whom TP gene expression could be measured. Intratumoral TP gene expression was evaluated using the Danenberg tumor profile method. TP gene expression was classified into two groups according to median values: high and low. Tissue TP expression was classified into two groups (positive and negative) by a pathologist. Clinicopathological variables were compared between groups with high and low TP gene expression (TP high and TP low groups). Results. No correlation was observed between TP gene expression (high and low groups) and any clinicopathological variables except survival rate. However, the survival rate was significantly lower in the TP high group (P < 0.05). TP gene expression was associated with tissue TP expression evaluated by immunohistochemical staining (P < 0.05). In addition, tumor microvessel density was significantly higher in the TP high group (P < 0.05). Conclusion. Expression of the TP gene in gallbladder carcinoma is associated with angiogenesis and may be a new independent prognostic parameter.