S100 proteins as cancer biomarkers with focus on S100B in malignant melanoma.

Although histochemical staining of the S100 protein family has been used for many years in the diagnosis of malignant melanoma, recent studies suggest one of the proteins comprising the S100 family, S100B, has particular utility in many aspects of the clinical management of malignant melanoma. This protein has been shown to be of use in staging malignant melanoma, in establishing prognosis, in evaluating treatment success and in predicting relapse. S100B is an independent prognostic factor and pretreatment circulating S100B concentrations predict duration of survival in melanoma patients. Survival is significantly longer in melanoma patients with normal S100B levels compared to those with elevated levels. Circulating S100B levels very sensitively detect metastatic growth of malignant melanoma, particularly in stage IV disease where S100B is certainly superior to other laboratory parameters. S100B concentrations reflect tumor mass. Serum S100B levels predict efficacy of treatment. Decreasing S100B concentrations reflect response to therapy while increasing S100B concentrations indicate tumor progression. Circulating S100B has a role to play in the decision to switch treatment regimens.