Plasma sialyltransferase as a tumor marker.

Neoplastic transformations are accompanied by an alteration in the composition of cell membrane glycoproteins, major structural components of the cell surface. Plasma sialyltransferase enzyme is involved in the transfer of sialic acid residues from cytosine monophosphate (CMP) sialic acid to a suitable acceptor. In the present study plasma sialyltransferase was assayed using a radiometric method, which measured the transfer of radioactivity from (14C) CMP sialic acid to desialated fetuin. Plasma sialyltransferase was measured in 127 normal and 91 cancer patients. The mean plasma sialyltransferase in the normal volunteers was 837 units (CPM/25 microliters plasma/hr). The mean plasma sialytransferase in 26 breast cancer patients, 22 lung cancer patients, 20 colon cancer patients, 5 ovarian cancer patients, 4 cervix cancer patients, 5 pancreas cancer patients, 6 prostate cancer patients, and 3 gastrointestinal tract cancer patients was 1710, 1406, 1344, 1227, 1233, 1406, 1250, and 1426 units, respectively. No significant difference was observed with respect to age. In 32 treated breast cancer patients the mean value was 757 units. Serial determinations in 17 patients correlated well with tumor burden. However, in 2 patients the plasma enzyme level did not correspond to tumor mass. These results indicate that plasma sialyltransferase is significantly elevated in patients with a variety of cancers. Plasma sialyltransferase determination may be useful in the followup of patients with a variety of cancers.