The clinical significance of sialyl Lewis antigen expression in the spread of gastric cancer. Flow cytometric dna analysis

We previously reported significant relationships between sialyl Lewis antigen expression on gastric cancer cells and both hepatic metastasis and clinical prognosis. The purpose of this study was to compare the expression of sialyl Lewis antigens on gastric cancer cells to elucidate the possible role of sialyl Lewis antigens in predicting the spread of a tumor with regard to histological findings. Subjects consisted of 38 patients with gastric cancer. For comparison we measured the values for sialyl Lewis a (sLe a ) and sialyl Lewis X (sLe x ) expression on the surface of about 10,000-30,000 cancer cells. Monoclonal antibodies CA19-9 and KM-93 were used to determine the frequency (%) and quantity (channel) of the expression by flow cytometry. We assessed the correlation of sLe a and sLe X expression with histological findings (depth of tumor invasion (pT), lymphatic invasion (ly), venous invasion (v), and lymph node metastasis (pN)), by comparing sLe a and sLe x expression in relation to the grade of histological findings. A significant relationship was found between lymphatic invasion and the frequency of sLe a expression (r = 0.40, p<0.05). The mean values of sLe a frequency in cases categorized as ly 2 (36.30) and ly 3 (31.81) were statistically higher than those in ly 1 cases (12.74) (p< 0.05). A significant relationship was also observed between lymph node metastasis and the frequency of sLe a expression (r = 0.46, p<0.01). The mean value of sLe a frequency in pN 3 cases (44.14) was statistically higher than those in pN 0 (17.11) and pN 1 (19.03) cases (p<0.05). Neither the depth of tumor invasion nor venous invasion showed any correlation with the expression of sialyl Lewis antigens. In conclusion the frequency of sLe a expression on the surface of gastric cancer cells was greater in those patients who developed lymphatic invasion and lymph node metastasis. However, the mechanism by which sialyl Lewis a expression is upregulated remains unclear.