Molecular–genetic and clinical characteristics of gliomas with astrocytic appearance and total 1p19q loss in a single institutional consecutive cohort

The prognostic significance of 1p19q loss in astrocytic gliomas has been inconclusive. We collected 57 gliomas with total 1p19q loss from among 218 cases of WHO grade-II/III gliomas operated at Keio University Hospital between 1990 and 2010. These tumors were classified as oligodendroglial or “astrocytic” by a WHO-criteria-based institutional diagnosis. Chromosomal copy number aberrations (CNAs), IDH 1/2 mutations, MGMT promoter methylation, and expression of p53 and ATRX were assessed. Survival outcome was compared between the two histological groups. Of the 57 codeleted gliomas, 37, 16, and four were classified as oligodendroglial, “astrocytic”, and unclassified, respectively. Comparative genomic hybridization revealed that although chromosome 7q/7 gain was more frequent in “astrocytic” gliomas, other CNAs occurred at a similar frequency in both groups. None of the “astrocytic” gliomas showed p53 accumulation, and ATRX loss was found in three of the 15 “astrocytic” gliomas. The estimated overall survival (OS) curves in the patients with codeleted oligodendroglial and “astrocytic” gliomas overlapped, and the median OS was 187 and 184 months, respectively. Histopathological re-assessment by a single pathologist showed consistent results. Gliomas with total 1p19q loss with “astrocytic” features have molecular and biological characteristics comparable to those of oligodendroglial tumors.