5-30% of high-grade brain tumors.
Constitutes 2.7% of brain tumors and 9.5% of all central nervous system gliomas.
Patients with oligodendrgliomas present in the fourth and fifth decades, and have symptoms, including seizures, headaches, and focal neurologic deficits.
On hematoxylin and eosin staining have round nuclei and fine delicate branching vessels are also defined by having an isocitrate dehydrogenase (IDH) gene family mutation and combined whole-arm losses of 1p and 19q (1p/19q codeletion).
Oligodendrogliomas are IDH mutant tumors that arise from oligodendroglioma precursors,and are divided into two tumor grades two and three.
Oligodendrogliomas demonstrate chromosome arm, 1p/19q codeletion.
5-10% of gliomas are mixed oligoastrocytomas.
Genetic signature correlates with improved outcome.
Improved survival with deletions of chromosomes 1p and 19q, present in over 50% of anaplastic oligodendrogliomas.
High response rate to treatment.
Ki-67 proliferation rate less than 5% in oligodendrogliomas and higher in anaplastic oligodendrogliomas.
Anaplastic oligodendroglioma is sensitive to chemotherapy and is linked to loss of heterozygosity for chromosomes 1p and 19q.
Anaplastic oligodendrogliomas are classified as IDH- mutant 1p/19q codeleted gliomas with increased mitotic activity, microvascular proliferation and/or necrosis.
Anaplastic oligodendrogliomas have a better prognosis than high-grade IDH mutant astrocytomas and a much better prognosis then IDH wild type glioblastomas..
Anaplastic. oligodendrogliomas account for approximately 5% of adult gliomas and 0.5% of all primary tumors affecting the CNS.
The optimal treatment for anaplastic oligodendroglioma is a combination of radio therapy and chemotherapy (Procarbazine, Lomustine and vincristine (PCV), or temozolomide) after resection.
Median survival for anaplastic oligodendroglioma is 15 years.
Two randomized studies comparing radiation therapy alone with radiation plus adjuvant chemotherapy with procarbazine, vincristine and lomustine or neoadjuvant initiation of the same agents for anaplastic oligodendroglioma did not improve survival (Cairncross, G, van den Bent MJ).
Disease-free survival is prolonged by the addition of chemotherapy at progressive disease following radiation.
Approximately 20% of patients with anaplastic oligodendrogliomas have a poor outcome and survive less than five years: Poor prognostic factors have yet to be defined.
The median survival ranges from 12 to 15 years.