Immunohistochemical expression of sialyl Tn, sialyl Lewis a, sialyl Lewis a-b-, and sialyl Lewis x in primary tumor and metastatic lymph nodes in human gastric cancer.

Sialyl Lewis Tn(STN), sialyl Lewis a(CA-9-9), sialyl Lewis a-b-(DU-PAN-2), and sialyl Lewis x(SLX) antigens were immunohistochemically examined in the primary tumor and metastatic lymph nodes in 35 patients with advanced gastric cancer. STN, CA-19-9, DU-PAN-2, and SLX were expressed in 91%, 60%, 31%, and 60% in the primary lesion, and 77%, 54%, 22%, and 51% in the metastatic lesion, respectively. In only four cases, (11%) were all four antigens expressed in both the primary and metastatic lesions. Three antigens were expressed in 49% of primary lesions and in 20% of metastatic lesions. Compared with expression in primary lesions, increased, unchanged and decreased expressions in metastatic lesions were noted in 23%, 37%, and 40% for STN, 20%, 40%, and 40% for CA-19-9, 17%, 57%, and 26% for DU-PAN-2, and 26%, 31%, and 43% for SLX, respectively. These results indicate that the tumor in the primary and metastatic lesions has a heterogeneous expression of sialyl-related antigens. However, metastases cannot be predicted based upon the expression of these antigens.