Protein S100B

Protein S100B is a member of a family of calcium binding proteins. S100B is present in astrocytes and glial cells in the brain and also in melanocytes. Protein S100B is currently being used in monitoring patients with malignant melanoma. Whilst the diagnosis of melanoma uses a combination of clinical and histological features, detection of metastases can be more difficult. A value greater than 0.2 µg/L is indicative of advanced disease (Stages 3 and 4) with a Positive Predictive Value of approximately 90%. Rising values can be seen 1-2 months in advance of clinical features of metastatic disease. The plasma concentration of S100B has been shown to be related to tumour burden and gives an early indication of successful response to chemotherapy. Values that fail to fall after one month of chemotherapy indicate the tumour is insensitive to the particular chemotherapy regime.

S100B is also a biochemical marker of brain injury and and a number of studies have been carried out to investigate its role in assessing and monitoring of closed head injuries and stokes.