[Expression of tumor-associated antigen LEA and its significance for pathological diagnosis]

Tumor marker, such as carcinoembryonic antigen (CEA), has low specificity in colorectal carcinoma diagnosis with lower value in early diagnosis of colorectal carcinoma. The previous studies showed that large external antigen (LEA) had high specificity for colorectal carcinoma tissue. This study was designed to evaluate the expression of colorectal carcinoma-associated antigen LEA in colorectal carcinoma and its significance for pathological diagnosis through the comparison of a new monoclonal antibody(ND-1) and anti-CEA monoclonal antibody in colorectal carcinoma tissue.

Expression of LEA in 170 colorectal cancer specimens, 41 colorectal adenomas, 32 surrounding non-cancerous large intestine tissues, and 27 normal mucosa specimens were detected with immunohistochemistry S-P method.

In the well, moderately, and poorly differentiated colorectal cancer, the positive rate of LEA was 100%, 83.1%, and 51.8%, respectively; CEA was 93.8%, 92.3%, and 70.4%, respectively. In adenoma, surrounding non-cancerous mucosa, and normal mucosa, the positive rate of LEA was 75.6%, 53.1%, and 14.8%, while CEA was 82.9%, 62.5%, and 40.7%, respectively. The expression of LEA exhibited higher selectivity in well differentiated adenocarcinoma (P < 0.01). CEA had similar selectivity in well, moderately, and poorly differentiated adenocarcinoma(P < 0.05). Compared with CEA, the expression of LEA had lower positive rate in non-cancerous tissue(P < 0.05). The expression of LEA and CEA showed significant correlation except in nomal mucosa. In histological diagnosis of colorectal cancer the sensitivity of LEA and CEA were 84.1% and 88.8%, respectively, the specificity were 48% and 35%, respectively.

LEA may be a tumor antigen that is related to cell differentiation and invasiveness. LEA can be used as a reference to the judgment of the malignancy degree of colorectal carcinoma. So it is a biological tumor marker with clinic value.