The objective of the current study was to investigate the clinical usefulness of serum fucose, fucosylated glycoproteins (fucoproteins), fucosyltransferase (FucT), and alpha-L-fucosidase in oral carcinoma. Blood samples were collected from 130 patients with untreated oral cancer (OC), from 75 patients with oral precancerous conditions (OPC), and from 100 healthy controls. Cancer patients were followed after the initiation of anticancer treatments, and 75 follow-up samples were also collected. Serum levels of fucose and alpha-L-fucosidase were measured spectrophotometrically. Fucoproteins were detected by using lectin-affinity chromatography. FucT activity was analyzed by using radioassay. Serum levels of fucose and fucoprotein were found to be increased significantly in patients with untreated OC compared with controls, patients with OPC, and complete responders (CR) to treatment; whereas the levels were comparable between untreated patients with OC and nonresponders (NR). A similar trend was observed for serum FucT levels, and changes in enzyme activity correlated well with fucose and fucoprotein alterations. The OPC group had significantly increased fucosylation of serum proteins. Furthermore, serum alpha-L-fucosidase activity was markedly higher in patients with untreated OC and in patients with OPC compared with controls. Using receiver operating characteristic curves, a cutoff for alpha-L-fucosidase was determined at >450.6 U/mL, which showed good sensitivity and specificity in OC and OPC compared with controls. The enzyme activity was declined in the CR group but remained higher in the NR group compared with pretreatment levels. Furthermore, various clinicopathologic characteristics were correlated positively with serum fucosylation changes. The findings of the current study suggest that serum fucosylation has clinical usefulness in the detection of early changes and for monitoring treatment response in patients with OC. Among the markers studied, serum alpha-L-fucosidase was identified as a useful marker for close monitoring of patients during post-treatment follow-up.
