CYTOKERATIN-POSITIVE CELLS IN BONE-MARROW FOR IDENTIFYING DISTANT MICROMETASTASIS OF GASTRIC-CANCER

Direct evidence of tumour seeding in distant organs at the time of sur gery for gastric cancer is not available. An immunocytochemical assay for epithelial cytokeratin protein may fill this gap since it is a fea ture of epithelial cells that would not normally be present in bone ma rrow. The bone marrow df 46 patients with primary gastric cancer was e xamined for tumour cells, using immunocytochemical techniques and anti body reacting with cytokeratin, a component of the intracytoplasmic ne twork of intermediate filaments. The monoclonal antibody CK2 recognise s a single cytokeratin polypeptide (human cytokeratin no. 18) commonly present in epithelial cells. The expression of tumour-suppressor gene s p53 and RE for the primary lesion was also determined using the mono clonal antibodies PAb 1801 and 3H9 respectively, and the proliferating activity was determined by the Ki-67 antigen labelling index for MIB- 1 antibody staining. Of these 46 patients, 15 (32.6%) presented with c ytokeratin-positive cells at the time of primary surgery. The positive findings were related to the undifferentiated tissue type and to the prominent depth of invasion, but not to other clinicopathological fact ors. In 2 of 15 (13.3%) patients, the depth of invasion was limited to the mucosa. The metastatic potential to bone marrow did not relate to expressions of p53 and RE genes, or to the proliferating activity of MIB-1 staining for the primary lesion of gastric cancer. As tumour cel ls in bone marrow are indicative of the general disseminative capabili ty of an individual tumour, this technique may be useful for identifyi ng patients at high risk of metastasis from a gastric tumour.