Comparison of S100 protein and MIA protein as serum marker for malignant melanoma

Background Detection of S100 beta in serum has been shown to be a significa nt prognostic market for malignant melanoma in earlier studies. Melanoma in hibiting activity (MIA) has recently been detected as a new serum marker fo r malignant melanoma. Materials and Methods: In the present study, serum le vels of S100 beta protein and MIA were measured over a time period of up to 18 months in 271 serum samples from 65 melanoma patients at different stag es of disease, during chemotherapy and/or immunotherapy. In addition, 46 se ra of control patients were analysed The aim of this study was to compare b oth potential markers. S100 beta was measured using the immunoluminometric assay LIA-mat(A) Sangtec(R) (Byk Sangtec Diagnostica) with a cut-off level of 0.12 mu g/l. MLA was determined by the MIA ELISA kit (Roche) using a cut -off level of 6.5 ng/ml. Results: In 53 patients a direct correlation of S- 100 values and clinical course could be observed (81.5%), whereas in 48 pat ients MIA-values and clinical course (73.8%) showed an association. S100 be ta levels were incorrectly elevated in 5 out of 25 sera, "false positive" ( 20%) and were in 8 out of 40 sera not elevated despite the detection of met astases "false negative" (20%). Assessing the MLA levels, 2 out of 25 probe s were false positive (8%) and 13 out of 40 probes false negative(32.5%). C onclusion: Our data strongly suggest that S100 and MIA represent serum tumo r markers that are valuable both in therapy-monitoring and in defection of tumour progression.