Immunohistochemical assessment of markers used for detection of lymph node micrometastases in patients with colorectal carcinoma

Background: Identification of lymph node metastasis is one of the most important indicators of poor prognosis in patients with colorectal carcinoma. Immunohistochemical techniques have improved possibilities of detection of micrometastases or even of isolated tumour cells in lymph nodes.
Aim of study: The aim of this study was to determinate whether cytokeratin 20 (CK20), cytokeratin AE1/AE3 (CK AE1/AE3), epithelial membrane antigen (EMA) and carcinoembryonic antigen (CEA) are markers of equal sensitivity to detect micrometastases in lymph nodes of colorectal carcinoma.
Material and methods: Immunohistochemical analysis was made on all 570 formalin-fixed, paraffin-embedded lymph nodes and tumours from 50 consecutive patients (at the age from 44 to 69) with colon or rectum carcinoma. They had undergone radical resection in the Centre of Oncology in Bydgoszcz in 2003-2006. In no patients were lymph node metastases detected by routine haematoxylin-eosin staining. Immunohistochemical examination was done by EnVision method using monoclonal antibodies CK AE1/AE3, CK 20, EMA and CEA produced by Dako.
Results: Immunohistochemical method detected micrometastatic disease in three lymph nodes from two patients. Noticeable micrometastases were found in sections from only one depth of lymph nodes. All micrometastatic tumour cells showed positive staining with antibody CK AE1/AE3 and negative with CK 20, EMA and CEA.
Conclusions: From among immunohistochemical markers the most sensitive for micrometastases detection was anti-cytokeratin antibody CK AE1/AE3. Identification of lymph node micrometastases in sections from only one depth indicates them to be a serial cut.