Serum sialic acid in malignant melanoma patients: an ROC curve analysis.

We have studied the total serum sialic acid as a possible diagnostic factor for the prognosis of patients with melanoma. The sialic acid concentration was determined in the sera of fifty melanoma patients (MP) and forty healthy persons (HP), by using an enzymatic method. We found a mean value of 67.52 +/- 17.32 mg/dl in MP and 57.11 +/- 12.98 mg/dl in HP (p < 0.005). In order to check whether this test could discriminate adequately between MP and HP, a complete statistical Receiver Operating Characteristic (ROC) curve analysis was performed. The cut-off value was 62.39 mg/dl. The area under the curve was 0.661. According to these results, the test could discriminate between both groups. However, due to the rise of sialic acid-rich acute-phase proteins in inflammatory processes, determination of total serum sialic acid would be more useful for diagnosis of melanoma stage and prognosis rather than for early detection and screening.