[Protein S100 beta and Melanoma Inhibitory Activity (MIA): a prospective study of their clinical value for the early detection of metastasis in malignant melanoma].

BACKGROUND: We examined whether serum values for proteins S100B and MIA could allow early and reliable screening of metastatic growth in melanoma.

PATIENTS AND METHODS: We carried out a prospective study from 1998 to 2005 in patients presenting non-metastatic melanomas with a Breslow score>0.75 mm. Four PS00B and MIA measurements per patient were performed at regular intervals over 1 to 2 years. Blood samples were analysed for PS100B and MIA using an ELISA technique.

RESULTS: Fifty patients were analysed. The maximum interval between collection of samples was 8 months. Metastatic development was noted in 15 patients. Where melanoma progressed to stage III, sensitivity was 33% for PS100B and 25% for MIA. Where it progressed to stage IV, sensitivity was 50% for PS100B and 30% for MIA. A rise in these values preceded discovery of metastasis in 3 cases for PS100B and of MIA in 1 case. Specificity of the assays was 100% for PS100B and 91% for MIA.

DISCUSSION: Sensitivity and specificity were better for PS100B than for MIA regarding detection of metastasis during follow-up of thick melanomas. The ELISA technique used in our study seemed to increase the specificity of the assay but not its sensitivity compared to other techniques used previously. We may thus confirm the benefits of PS100B assay for early detection of metastasis in melanomas. However, this laboratory surveillance method is not an acceptable substitute for regular clinical follow-up due to its low sensitivity.