Evaluation of water soluble and lipid soluble sialic acid levels as tumor markers.

Serum sialic acid and lipid-soluble sialic acid was measured in 39 cancer patients, 16 patients with Crohns disease, 13 patients with rheumatoid arthritis, 28 patients with osteoarthritis, and 40 normal patients. Sialic acid was also determined in several patients who had undergone extensive chemotherapy or radiation. Elevations of sialic acid were observed in 33 of 39 cancer patients (sensitivity = 85%). No elevations were observed in the normals (specificity = 100%). However, 11 of 13 patients with rheumatoid arthritis and 9 of 16 patients with Crohns disease had elevated sialic acid. Patients undergoing extensive chemotherapy or radiation for two months prior to sialic acid measurement frequently had normal values even though tumor was present. Four patients, who were found to have cysts instead of cancer on biopsy or pathological examination, had normal sialic acid values. Three patients with active leukemia had elevated sialic acid, but three patients whose leukemia was in remission had normal sialic acid levels. Correlations were also found between sialic acid from an enzymatic total sialic acid and the Ehrlich sialic acid, and also between total sialic acid measured by the Ehrlich method and lipid soluble sialic acid.