Differences in Release Mechanisms and Distributions for Sialyl Lea and Sialyl Lex Antigens in Colorectal Cancer

Background: To investigate colorectal cancer-related carbohydrate antigen release and distribution, we evaluated serum levels of sialyl Lea (CA19–9) and sialyl Lex antigen (SLX) in blood samples obtained from both a peripheral vein and a tumor’s draining vein.Methods: Blood samples were obtained during surgery from 126 patients. Based on these samples, patients were placed into a high-antigen group, with a concentration above a selected cutoff value, or into a low-antigen group, with a tumor marker concentration below that same value. The blood samples obtained from peripheral veins were designated by the “p” prefix, and samples from drainage veins were designated by the “d.”Results: Serum d-SLX levels were significantly higher than p-SLX levels (P, .0001), although there was no difference between those of d-CA19–9 and p-CA19–9. Only 1 (3.6%) of 28 patients in the high d-CA19–9 group had a low p-CA19–9. In contrast, 6 (33.3%) of 18 patients in the high d-SLX group had low p-SLX levels (P 5 .0103). Correlations between pathological variables and either p-CA19–9 levels or d-CA19–9 levels were similar. However, both distant metastasis and venous invasion did prove to be independent variables related to d-SLX levels, as shown by logistic regression analysis.Conclusions: SLX may drain predominantly via the draining veins of colorectal tumors into portal circulation, whereas CA19–9 may drain via another route.