Serum levels of S-100 protein and 5-S-cysteinyldopa as markers of melanoma progression.

Serum S-100 protein is widely used as a marker of melanoma and since 5-S-cysteinyldopa (5-S-CD) is a precursor of melanin its serum and urinary levels can reflect melanoma progression. In this study we examined the concentration changes of serum S-100 protein and 5-S-CD in 252 melanoma patients of different clinical stages. Serum samples were taken from 252 melanoma patients at 860 times, from June 1996 to July 1998. The serum S-100 protein was measured by the immunoluminometric assay, levels of 5-S-CD was determined by HPLC. The value of S-100 protein in patients with primary melanoma (0.11m mg/l) and in patients without symptoms (0.15 m mg/l) ranged around the normal level (0.01 0.12 m mg/l). There was a significant difference between the values of patients with or without symptoms. There was a similarly significant difference between the S-100 values of clinical Stage I (0.11 mg/l) and Stage III (2.91 mg/l) as well as between those of clinical Stage II (0.47 mg/l) and Stage III (2.91 mg/l), respectively. Analyzing the values of patients with symptoms we observed significant difference between the S-100 protein values of patients with primary tumor and those with solitary or multiple distant metastases. In case of 5-S-CD significant difference was found between clinical Stage I and III as well as clinical Stage II and III. Furthermore, there was a significant difference between the mean marker values of patients with primary tumor, lymph node, lung metastasis and clinical stage III.