Identification of occult micrometastases in patients with early gastric cancer using anti-cytokeratin monoclonal antibodies.

The presence of occult micrometastases was evaluated in 1488 lymph nodes removed from 139 patients with node-negative early gastric cancer (EGC). Additional multiple levels of the lymph nodes were examined with haematoxylin-eosin staining and keratin immunostaining. Occult nodal micrometastases were detected in 24 patients (17%) in one or more lymph nodes dissected after a gastrectomy. The cases investigated were a small group from a total of 412 EGC patients who underwent surgical treatment in our hospital between 1976 and 1997; the mean follow-up period was 9 years (range 1-22). We found no significant differences between cytokeratin-negative and positive patients regarding the following clinicopathological parameters: age, gender, tumour size and site, macroscopic and microscopic type, depth of invasion and type of infiltration, according to Kodama's classification. The survival rate at 5 years was 88% and 87% for cytokeratin-negative and positive patients, respectively (log-rank = 0.6; ns). Our data suggest that occult micrometastases do not add useful information and immunohistochemical studies to detect them are probably unnecessary.