Serum S-100 protein: a potentially useful prognostic marker in cutaneous melanoma

Summary S‐100, an acidic calcium‐binding protein, is present within cells of neuroendocrine origin. Its value in the immunohistochemical diagnosis of tumours of melanocytic origin is well established. More recently, a potential role has been proposed for the serum concentration of this protein as a marker of metastatic melanoma disease activity. In the present study, the concentration of serum S‐100 protein was measured in 97 patients with histologically proven malignant melanoma who were attending a dermatology and/or oncology department for the follow‐up of their disease. Serum S‐100 was also measured in 48 control subjects without malignant melanoma. The clinical stage of the patients was classified according to the criteria of the American Joint Committee on Cancer into stages I‐IV. The median (range) serum S‐100 protein concentration was significantly higher in stage I (0·11 (0·1–0·21) μg/L, P