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Introduction: Intratumoral expression of the epithelial cellular adhesion molecule (EpCAM) is of great prognostic impact in various malignant tumors. However, less data about its role in gastric cancer is available. Therefore, we investigated the expression patterns of EpCAM in this malignancy and its prognostic impact on gastric cancer patients undergoing primary surgical therapy.
Patients and Methods: The intratumoral protein expression of EpCAM was assessed in 163 gastric cancer patients undergoing primary surgical therapy (61 diffuse-, 62 intestinal-, 32 mixed-type and 8 unclassified tumors) by immunohistochemistry, using the monoclonal antibody Ber-EP4. Intensity of staining was classified according the HercepTest-Score as a standardized scoring system. Afterwards intratumoral EpCAM expression patterns were correlated with clinicopathologic parameters including overall survival.
Results: EpCAM expression was observed in 77% of the tumors. Of these, 58% (n=74) presented a homogeneous intratumoral EpCAM expression while 42% presented a difference between the centre and invasion front of the tumor. Interestingly, tumors with high EpCAM expression in the invasion front were associated with a significantly higher proportion of lymph node metastases and lower median overall survival (p=0.03; p=0.001). This observation was significantly (p=0.04) higher in diffuse type of gastric cancers compared to the intestinal type. Multivariate survival analysis identified high EpCAM expression in the invasion front as an independent prognostic factor (Cox-Regression analysis).
Conclusion: Intratumoral EpCAM expression in the invasion front was associated with a significant decrease in overall survival of patients with gastric cancer. Considering the discontenting results of the current neoadjuvant/adjuvant concepts for gastric cancer patients, EpCAM might provide a promising target for a neoadjuvant/adjuvant immunotherapy.