Sialyltransferase levels and sialic acid concentrations in sera of patients with malignant melanomas.

Serum levels of sialyltransferase and sialic acid were measured in patients with malignant melanomas (n = 49), healthy control persons (n = 20), and patients with non-malignant skin disorders (n = 30). Both parameters were found to be higher in malignant melanoma patients than in healthy control persons, but they were not significantly higher in melanoma patients than in patients with benign skin disorders, unless widespread dissemination of metastases had occurred. The highest values were measured in patients with liver and lung metastases. No general correlation was found between sialyltransferase activities and sialic acid concentrations. Sialic acid concentrations seem to be a better index for tumor spreading than sialyltransferase activities. In early stages of the disease, shedding from tumor cells is not the major source of elevated serum levels of sialyltransferase and sialic acid, respectively.