Reduction in membranous immunohistochemical staining for the intracellular domain of epithelial cell adhesion molecule correlates with poor patient outcome in primary colorectal adenocarcinoma
Epithelial cell adhesion molecule (EpCAM) is a multifunctional transmembrane glycoprotein expressed on both normal epithelium and epithelial neoplasms such as gastric, breast, and renal carcinomas. Recent studies have proposed that the proteolytic cleavage of the intracellular domain of EpCAM (EpCAM-ICD) can trigger signalling cascades leading to aggressive tumour behavior. The expression profile of EpCAM-ICD has not been elucidated for primary colorectal carcinoma. In the present study, we examined EpCAM-ICD immunohistochemical staining in a large cohort of patients with primary colorectal adenocarcinoma and assessed its performance as a potential prognostic marker.
Immunohistochemical staining for EpCAM-ICD was assessed on tissue microarrays consisting of 137 primary colorectal adenocarcinoma samples. Intensity of staining for each core was scored by 3 independent pathologists. The membranous EpCAM-ICD staining score was calculated as a weighted average from 3 core samples per tumour. Univariate analysis of the average scores and clinical outcome measures was performed.
The level of membranous EpCAM-ICD staining was positively associated with well-differentiated tumours (p = 0.01); low preoperative carcinoembryonic antigen (p = 0.001); and several measures of survival, including 2-year (p = 0.02) and 5-year survival (p = 0.05), and length of time post-diagnosis (p = 0.03). A number of other variables — including stage, grade, and lymph node status—showed correlations with EpCAM staining and markers of poor outcome, but did not reach statistical significance.
Low membranous EpCAM-ICD staining might be a useful marker to identify tumours with aggressive clinical behavior and potential poor prognosis and might help to select candidates who could potentially benefit from treatment targeting EpCAM.