It will be of interest to investigate whether increased IGFBP2 in blood or primary tumor represents specific changes in signal transduction, metabolism, or biological functions in lung cancer, as was reported in glioma; in that cancer, increased IGFBP2 might serve as a biomarker for PTEN status and PI3K/AKT activation [40] or Ink4a-Arf status [41]. Here, PTEN is linked to central nervous system cancer.