Improved Procedure for Determination of Serum Lipid-Associated Sialic Acid: Application for Early Diagnosis of Colorectal Cancer

We have developed a simple and reliable procedure for determining serum levels of lipid-associated sialic acid (LASA) in crude preparations. This method extracts essentially all gan-gliosides, excludes glycoprotein-bound sialic acuid, and gives LASA values (0.5–1.0 mg/dL) in good agreement with values for isolated serum gangliosides. The procedure was used to determine serum levels of LASA in patients with colorectal cancer, in patients with non-malignant diseases (pathological control subjects), and in normal control subjects), The results indicated that the percentages of total sialic acid (TSA) comprised by LASA (LASA/TSA × 100) were elevated in patients with the earliest stages of colorectal cancer, compared with percentages in normal control subjects (P