Expression of thrombomodulin in squamous cell carcinoma of the lung: its relationship to lymph node metastasis and prognosis of the patients

Thrombomodulin (TM) is a type of thrombin receptor that was identified originally on the endothelium and acts as a natural anticoagulant through converting thrombin from a procoagulant protease to an anticoagulant. We reported previously that TM was also expressed in the squamous epithelium mainly at the intercellular bridges. In this study, we examined TM expression in the primary lesions of 81 patients with squamous cell carcinomas (SCCs) of the lung and in the lymph node metastatic lesions of 39 patients using immunohistochemical methods. The carcinoma tissues expressed TM mainly at the cell–cell boundaries and also in the cytoplasm. When TM expression was compared between the primary and metastatic lesions in the 39 patients who had lymph node metastasis, 26 (67%) showed decreased TM expression, 13 (33%) showed no change, and none (0%) showed an increase in the metastatic lesions. Wilcoxon's signed-rank test indicated that tumor cells that were positive for TM expression were significantly rarer in the metastatic lesions than in the primary tumors ( P