Increased expression of sialyl Lewis(x) antigen in penetrating growth type A early gastric cancer.

Early gastric cancer can be divided morphologically into two categories, penetrating growth type-A (Pen-A type) and other growth types (non-Pen-A types). Sialyl Lewis(x) antigen has been demonstrated to play an important role in tumor metastasis by serving as a functional ligand in the cell adhesion system. The aim of this study is to ascertain whether or not sialyl Le(x) antigen expression correlates with tumor growth patterns of early gastric carcinoma. An immunohistochemical assay was performed using monoclonal antibody CSLEX1 in 12 Pen-A type and 79 non-Pen-A type cancers. Scoring was based on the percentage of immunoreactive cells: negative, low expression (< or = 25%), and high expression (> 25%). Lymph node metastasis was found more frequently in Pen-A type than non-Pen-A type cancers (P=0.0004). Furthermore, sialyl Le(x) antigen high expression was detected more often in Pen-A type cancers (7 out of 12; 58.3%) than non-Pen-A type cancers (13 out of 79; 16.5%) (P=0.0036). Multivariate logistic regression analysis showed that these variables are related independently to the Pen-A type and the non-Pen-A type tumor growth patterns. These data suggest that the difference in sialyl Le(x) antigen expression between the Pen-A type and non-Pen-A type tumor growth patterns of early gastric cancer may, at least partially, reflect different biological behavior during tumor progression.