Evaluation of serum sialic acid fractions as markers for malignant melanoma

Increased total serum sialic acid levels have proved to be a useful non-specific marker of various neoplastic diseases including melanoma. In some malignancies, specific fractions of sialic acid were reported to be more reliable for monitoring disease progression. In this study various fractions of sialic acid were measured in the sera of Bomirski melanoma-bearing Syrian hamsters using the modified thiobarbituric acid method of Skoza and Mohos. Significantly higher serum levels of total sialic acid, 601.0 +/- 49.1 micrograms/ml, were demonstrated in animals with melanoma in comparison with control hamsters, 463.1 +/- 33.0 micrograms/ml (P < 0.01). Free sialic acid concentration was found to be negligible compared with that found in the sera of melanoma patients. Lipid bound sialic acid measurements carried out according to Bhatavdekar et al. were shown to be influenced by interfering substances. Hence, only the estimation of total sialic acid in sera can be recommended for monitoring melanoma progression. Bomirski melanoma proved to be a good model of human melanoma.