Among the proteins CDKN1B (p27/Kip1), ICAM1, MLH1, MMP11 and ST8SIA1, which we found were significantly decreased in the plasma from the patients with GP, only the CDKN1B decrease has been previously reported for plasma by others; the mutation and deregulation of this tumour suppressor protein that is involved in the regulation of cell-cycle progression is a common feature of many cancers38, including glioma, where it has been significantly associated with short survival39,40 and glioma grading40 in larger population studies. This evidence concerns the gene ST8SIA1 and central nervous system cancer.