title: S100B and S100B autoantibody as biomarkers for early detection of brain metastases in lung cancer.
abstract: BACKGROUND
  S100B is an astrocytic protein that enters the blood stream when there is disruption of the blood-brain barrier (BBB). Over time, antibodies against S100B develop in the sera of patients who experience persistent or repeated BBB disruptions. We explored the use of serum S100B protein and S100B autoantibodies for the detection of brain metastasis in patients with lung cancer.
  
  
  METHODS
  One hundred and twenty eight untreated patients with lung cancer who had brain imaging performed as part of their routine evaluation, participated. Serum S100B protein levels were measured by direct ELISA and S100B autoantibody levels by reverse ELISA. These levels in patients with brain metastases were compared alone and in combination to those without brain metastases.
  
  
  RESULTS
  Eighteen (14%) patients had brain metastasis at the time of lung cancer diagnosis. An S100B cutoff of 0.058 ng/mL had a sensitivity of 89% and specificity of 43% for brain metastasis. When an autoantibody threshold of <2.00 absorbance units was used in conjunction with S100B, the sensitivity remained at 89%, and the specificity increased to 58%. The overall accuracy was 51% with S100B alone, improving to 62.5% when combined with autoantibodies.
  
  
  CONCLUSIONS
  Serum S100B and S100B autoantibody levels may help to identify which lung cancer patients have brain metastases.
authors.affiliation: Respiratory Institute, Cleveland Clinic, Cleveland, OH 44195, USA ;
authors.forename: Humberto
authors.initials: H
authors.lastname: Choi
authors.affiliation: Cerebrovascular Research, Biomedical Engineering and Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH 44195, USA ;
authors.forename: Vikram
authors.initials: V
authors.lastname: Puvenna
authors.affiliation: Cerebrovascular Research, Biomedical Engineering and Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH 44195, USA ;
authors.forename: Chanda
authors.initials: C
authors.lastname: Brennan
authors.affiliation: Imaging Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
authors.forename: Shamseldeen
authors.initials: S
authors.lastname: Mahmoud
authors.affiliation: Quantitative Health Sciences, Cleveland Clinic, Cleveland, OH 44195, USA.
authors.forename: Xiao-Feng
authors.initials: XF
authors.lastname: Wang
authors.affiliation: Imaging Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Phillips
authors.affiliation: Cerebrovascular Research, Biomedical Engineering and Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH 44195, USA ;
authors.forename: Damir
authors.initials: D
authors.lastname: Janigro
authors.affiliation: Respiratory Institute, Cleveland Clinic, Cleveland, OH 44195, USA ;
authors.forename: Peter
authors.initials: P
authors.lastname: Mazzone
keywords: Biomarker; S100B; brain metastasis; lung cancer; small vessel disease (SVD)