Feng Hui, Song Jin-dan
Key Laboratory of Cell Biology, Ministry of Public Health of China, China Medical University, Shenyang 110001, P. R. China.
Ai Zheng. 2002 Jun;21(6):658-62.
BACKGROUND & OBJECTIVE: 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.
癌胚抗原（CEA）等肿瘤标志物在结直肠癌诊断中特异性较低，对结直肠癌早期诊断价值不大。既往研究表明，大外抗原（LEA）对结直肠癌组织具有较高特异性。本研究旨在通过比较新型单克隆抗体（ND-1）和抗CEA单克隆抗体在结直肠癌组织中的表达，评估结直肠癌相关抗原LEA在结直肠癌中的表达及其对病理诊断的意义。
采用免疫组织化学S-P法检测170例结直肠癌标本、41例结直肠腺瘤、32例癌旁大肠组织及27例正常黏膜标本中LEA的表达。
在高分化、中分化和低分化结直肠癌中，LEA的阳性率分别为100%、83.1%和51.8%；CEA分别为93.8%、92.3%和70.4%。在腺瘤、癌旁黏膜和正常黏膜中，LEA的阳性率分别为75.6%、53.1%和14.8%，而CEA分别为82.9%、62.5%和40.7%。LEA在高分化腺癌中的表达具有更高的选择性（P<0.01）。CEA在高分化、中分化和低分化腺癌中具有相似的选择性（P<0.05）。与CEA相比，LEA在非癌组织中的阳性率较低（P<0.05）。除正常黏膜外，LEA和CEA的表达呈显著相关。在结直肠癌的组织学诊断中，LEA和CEA的敏感性分别为84.1%和88.8%，特异性分别为48%和35%。
LEA可能是一种与细胞分化和侵袭相关的肿瘤抗原。LEA可作为判断结直肠癌恶性程度的参考指标。因此，它是一种具有临床价值的生物肿瘤标志物。
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