Detection of micrometastases of lymph nodes in patients with colorectal cancer: a comparative study between immunohistochemistry and RT-PCR

Objective To compare the diagnostic value between immunohistochemistry and RT-PCR in detecting micrometastases of lymph nodes of colorectal cancer. Methods 326 lymph nodes from 40 colorectal cancer patients with histologically netative node were studied. A immunohistochemistry was performed by the streptavidin peroxidase conjugataed method using a monoclonal antibody specifically a-gainst cytokeratin 20 (CK20) , and RT-PCR was used to detect the expression of CK20 mRNA in regional lymph node. Results Forty-one and 105 lymph nodes were found to have micrometastases by immunos-raining with CK20 antibody and CK20 mRNA RT-PCR,and the positive rate was 12.8% and 32.2% .re-spectively (P < 0.05 ). Conclusion RT-PCR is more sensitive than immunohistochemistry for detection of micrometastases in lymph nodes of colorectal cancer with CK20 as marker. Key words: Colorectal carcinoma;  Micrometastasis;  Immunohistochemistry