Serum sialic acid forms as markers for head and neck malignancies.

The value of protein-bound (PSA), lipid-bound (LSA) and free sialic acid (FSA) levels in the serum as marker was assessed together with its use as a prognostic indicator for head and neck cancers in 165 patients followed-up for over 18 months. Elevated PSA levels were found in 57% of patients with benign disorders, 52% with primary head and neck cancers, and 75% with metastatic cancer. Strong correlation was found between PSA and the regression/progression of the disease. The PSA level essentially returned to normal in patients with favorable prognosis and PSA levels showed a tendency to increase or remain at high levels in patients with a poor prognosis. These results suggest that PSA level is a better prognostic indicator in head and neck cancers, for which there is no available tumor marker.