Differences in release mechanisms and distributions for sialyl Le(a) and sialyl Le(x) antigens in colorectal cancer

Background: To investigate colorectal cancer-related carbohydrate antigen r elease and distribution, we evaluated serum levels of sialyl Le(a) (CA19-9) and sialyl Le(x) antigen (SLX) in blood samples obtained from both a perip heral vein and a turner's draining vein. Methods: Blood samples were obtained during surgery from 126 patients. Base d 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, w ith a tumor marker concentration below that same value. The blood samples o btained from peripheral veins were designated by the "p" prefix, and sample s 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 = .0103). Correlations between pathological variables a nd either p-CA19-9 levels or d-CA19-9 levels were similar. However, both di stant 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 colorect al tumors into portal circulation, whereas CA19-9 may drain via another rou te.