Long survival and therapeutic responses in patients with histologically disparate high-grade gliomas demonstrating chromosome 1p loss

Object. Allelic loss of chromosome 1p is a powerful predictor of tumor chem osensitivity and prolonged survival in patients with anaplastic oligodendro gliomas. Chromosome 1p loss also occurs in astrocytic and oligoastrocytic g liomas, although less commonly than in pure oligodendroglial tumors. This o bservation raises the possibility investigated in this study that chromosom e 1p loss might also provide prognostic information for patients with high- grade gliomas with astrocytic components. Methods. The authors report on seven patients with high-grade gliomas compo sed of either pure astrocytic or mixed astrocytic-oligodendroglial phenotyp es, who had remarkable neuroradiological responses to therapy or unexpected ly long survivals. All of the tumors from these seven patients demonstrated chromosome 1p loss, whereas other genetic alterations characteristic of hi gh-grade gliomas (p53 gene mutations, EGFR gene amplification, chromosome 1 0 loss, chromosome 19q loss, or CDKN2A/p16 deletions) were only found in oc casional cases. The authors also assessed the frequency of chromosome 1p lo ss in a series of anonymous high-grade astrocytoma samples obtained from a tumor bank and demonstrate that this genetic change is uncommon, occurring in only 10% of cases. Conclusions. Although any prognostic importance of chromosome 1p loss in as trocytic or mixed astrocytic-oligodendroglial gliomas can only be determine d in larger and prospective series, these findings raise the possibility th at some high-grade gliomas with chromosome 1p loss, in addition to pure ana plastic oligodendrogliomas, may follow a more favorable clinical course.