Prognostic value and clinicopathological correlation of thrombomodulin in squamous cell carcinoma of the human lung

Aggregation of host platelets by circulating tumor cells is believed to play an important role in the metastatic process. Because thrombomodulin (TM) is one of the major mediators of the activation of the anticoagulant protein C by thrombin, we examined 136 primary tumor tissues and 45 metastatic lymph node tissues of lung squamous cell carcinomas for TM expression using immunohistochemical methods. The number of tumors with positive TM staining was less in metastatic tumors (44%) than in primary tumors (74%) (P < 0.01). Of various clinicopathological factors, better differentiation and lower N stage were significantly associated with TM expression. A loss of TM expression was associated with a shortened survival in 113 patients who underwent complete resection of the lung tumor (P < 0.01). In this group, TM expression and tumor-node-metastasis staging were independent significant determinants for survival, determined using Cox's multivariate survival analysis. Since TM is apparently associated with tumor progression and differentiation, this correlation may serve as a prognostic indicator in squamous cell carcinoma of the lung.