Role of podoplanin expression in esophageal squamous cell carcinoma: a retrospective study.

Lymphatic metastasis is the predominant cause of the low overall survival of patients with esophageal squamous cell carcinoma (ESCC), as there are no faithful methods available predicting early metastasis. Recent studies suggest an effect of podoplanin expression on metastatic spreading to lymph nodes. The purpose of this study was to investigate the influence of podoplanin expression on lymphatic metastasis and tumor cells, and to find the relationship between podoplanin expression and prognosis of patients with ESCC. We evaluated the level of podoplanin expression on tumor cells and the lymphatic vessel density change of tumor mass compared with normal tissue from the same patient through D2-40 immunohistochemistry staining, and analyzed associations between these two variables and various clinicopathologic parameters individually or conjunctively. There was an association between podoplanin expression and the frequency of lymph node metastases. In 45 patients (80%), podoplanin was expressed on the tumor cells. Twenty-one patients (37.5%) showed high levels of expression. The 5-year disease-free survival rate (5%) for patients with high levels of podoplanin expression was significantly lower (P < 0.001) than for patients with low and moderate expression of podoplanin (54% and 27%, respectively). We concluded that podoplanin is expressed frequently in ESCC, and that the expression of podoplanin on cancer cells, lymphatics, or both is correlated with lymphatic metastasis and clinical outcome.