Prognostic significance of EpCAM expression in human esophageal cancer

EpCAM is a 40-kDa epithelial transmembrane glycoprotein that has a well-known role in Ca2+-independent homophilic cell-cell adhesion. Recently, correlations between EpCAM expression and clinicopathological features have been investigated in various cancers. We examined EpCAM expression in surgical specimens from esophageal cancer patients (n=138), using real-time RT-PCR, immunohistochemistry and ELISA. The mean expression level of EpCAM mRNA in tumor tissues was significantly higher than that in corresponding normal tissues (P<0.0001). Immunohistochemically, positive staining for EpCAM was found in 135 (97.8%) of the 138 primary tumor specimens. EpCAM expression was correlated with tumor depth (P=0.0005), stage (P=0.0037), blood-vessel invasion (P=0.0397) and infiltrative growth pattern (P=0.0015). The survival rates of patients with tumors with high EpCAM expression was significantly higher than those for patients with tumors with low EpCAM expression (P=0.0213). Furthermore, the serum EpCAM levels of patients with esophageal cancer were significantly higher than those of normal volunteers (P=0.0221). The survival rates of patients with a high EpCAM level in the peripheral vein were also significantly higher than those for patients with a low serum EpCAM level (P=0.0291). The serum EpCAM level in the peripheral vein was independently associated with prognosis (P=0.0074; hazard ratio 7.40). Tumor-specific EpCAM expression and release into the circulation may serve as effective immunotherapy in esophageal cancer patients.