Abstract: To investigate the role of cytokeratin in determining the lymph node micrometastasis in nodenegative gastric carcinoma with anticytokeratin antibody. Methods：Two hundred and fortytwo dissected lymph nodes from 50 patients with nodenegative gastric carcinomas were examined with hematoxylin and eosin (HE), antihuman CEA (carcinoembryonic antigen) antibody, anticytokeratin 19 (CK19) antibody and anticytokeratin 20 (CK20) antibody. Of them, 28 patients were followed up for 48 to 90 months. Results： Micrometastases were identified in 11 of 50 patients (22%) and in 18 of 242 lymph nodes (7.44%) by immunohistochemical staining. Positive reactions were found in 10 lymph nodes (4.13%) stained with CEA, and in 17 (7.02%) or 16 (6.61%) stained with CK19 or CK20. No lymph node stained by HE showed positive result. A higher incidence of micrometastasis was found in the patients with recurrent disease (42.86%, 3/7) compared with result from recurrencefree patients (9.52%, 2/21). Survival analysis demonstrated that the diseasefree survival time in micrometastasis positive patients was shorter than that of the negative ones. But there was no significant difference of the cumulative survival rate. Conclusions：CK is a more sensitive marker than CEA for detection of metastases, and the specificity of CK20 is better than CK19 in this assay. Micrometastases might correlate with worse prognosis for patients with histologic node negative gastric cancer.

Key words: Stomach neoplasm, Keratin, Lymphatic metastasis