Use of serum 5-S-CD and S-100B protein levels to monitor the clinical course of malignant melanoma.

5-S-Cysteinyldopa (5-S-CD) is a precursor of pheomelanin. S-100B protein is a low molecular weight, acidic, calcium binding, cytoplasmic protein. In this study, the concentration changes of serum 5-S-CD and S-100B protein in melanomas of all stages were examined in parallel and patients were monitored during and after treatment. Serum samples were taken from 478 melanoma patients on 1924 occasions. Of these, 180 cases were regularly monitored. Concentrations of 5-S-CD were determined by high performance liquid chromatography (HPLC), S-100B protein by immunoluminometric assay. The mean/median concentrations of 5-S-CD and S-100B protein in Stage I, II and III patients and in the control group ranged around the normal level. In Stage IV patients, 58.4/50.6% sensitivity, 100% specificity and 100/86.6% positive predictive values were obtained concerning S-100B protein and 5-S-CD, respectively. Recurrence was observed in 57/180 of the regularly monitored patients in Stages I, II and III. In 10/57 (17.5%) of these patients suffering from any type of disease progression increases in both marker levels preceded the detection of metastasis by conventional methods. We can confirm that changes in both marker concentrations correlated with the stages of the patient. The markers are most sensitive in Stage IV patients and also have a high specificity in these patients. In Stage IV melanoma patients, 5-S-CD and S-100B protein levels are independent significant prognostic factors. In almost one fifth of patients both marker levels increased before the detection of metastatic disease with other appropriate, routinely scheduled investigations. This study suggests that serial serum marker measurements in the management and follow-up of melanoma patients should be examined further.