Abstract
Changed activities of glycosyl transferases are thought to correlate with malignant degeneration of cells. This was found by examination of serum samples of cancer patients [1, 9, 10]. Particular importance is attached to one specific glycosyl transferase, namely sialyl transferase. This enzyme incorporates “activated” sialic acid into appropriate acceptors. Sialic acid is frequently found in glycoproteins and glycolipids as a terminal sugar residue. It has been demonstrated by our group and others that sialyl transferase shows greater activity in the serum or plasma of cancer patients than in that of normal healthy subjects [2–5].