Significance of serum protein S100 levels in screening for melanoma metastasis: does protein S100 enable early detection of melanoma recurrence?

A number of recent reports suggest serum protein S100 as a prognostic param eter in patients with metastatic melanoma. In the present study, serum prot ein S100 was investigated as a tumour marker for screening for melanoma met astasis in patients attending regular follow-up examinations. During the pe riod from September 1997 to December 1998, serum protein S100 levels were m easured by an immunoluminometric assay in 411 consecutive high risk melanom a patients (666 samples) and in 120 control subjects. Melanoma patients wit h resected primary tumours with a tumour thickness of 1.5 mm or more with r esected metastasis were included in the study. Overall, 41 of the 411 patie nts developed metastasis during the period of observation. According to the distribution of protein S100 levels, the following different cut-off value s were examined: 0.08 mug/l (95 percentile of the control group) and 0.13 m ug/l (95 percentile of the group of melanoma patients without metastasis). The test efficiency for protein S100 as a diagnostic test for the detection of metastasis was highest for the cut-off value of 0.13 mug/l. In eight of the 41 patients (19.5%), elevation of protein S100 was the first sign of r ecurrence. Of the 41 patients with metastatic disease, 13 had elevated prot ein S100, giving a sensitivity of 0.32. The specificity for the detection o f metastasis was 0.96. In eight of the 14 patients (57%) who developed dist ant metastasis, elevated S100 values were the first sign of tumour progress ion. In conclusion, determination of serum protein S100 levels enables earl ier detection of distant metastasis in patients at high risk for metastasis . The impact on survival time needs to be investigated in follow-up studies . (C) 2000 Lippincott Williams & Wilkins.