# Oligodendroglioma, IDH-mutant and 1p/19q-codeleted

Source: https://onco.cc/cancers/oligodendroglioma/  
OnCo record `oligodendroglioma` (Cancer). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Oligodendroglioma is the adult brain tumour most responsive to chemotherapy. It is recognised by an IDH mutation together with loss of parts of chromosomes 1 and 19, and after surgery it is treated with radiotherapy plus the PCV drug combination, or, for small grade 2 tumours, with vorasidenib or watchful waiting.

## Summary

Oligodendroglioma, IDH-mutant and 1p/19q-codeleted is defined in WHO 2021 by the combination of an IDH1 or IDH2 mutation with whole-arm codeletion of 1p and 19q; TERT promoter mutations are near universal and CIC and FUBP1 mutations common. It is graded 2 or 3 by mitotic activity, microvascular proliferation and necrosis; there is no grade 4. Calcification, frontal location and seizures are typical, and the tumour infiltrates cortex widely, so complete resection is often impossible.

The codeletion was first linked to chemosensitivity by Cairncross in 1998, and two trials that opened in the 1990s proved it: RTOG 9402 (radiotherapy with or without PCV before it) and EORTC 26951 (radiotherapy with or without PCV after it). In codeleted tumours the long-term reports in 2013 showed survival roughly doubled, with a median of 14.7 years against 7.3 years in RTOG 9402 and median survival not reached against 112 months in EORTC 26951, so radiotherapy followed by PCV became the standard for grade 3 disease and, after RTOG 9802, for high-risk grade 2 disease. CODEL is testing whether temozolomide can replace PCV, which is harder to tolerate; CATNON did not include codeleted tumours.

For grade 2 tumours with residual or recurrent disease and no pressing need for radiotherapy, INDIGO included oligodendroglioma alongside astrocytoma and vorasidenib is now an approved alternative to observation. Because patients live for many years, the cumulative cognitive effects of radiotherapy, the timing of treatment after surgery and the sequencing of vorasidenib, chemotherapy and radiotherapy are the live questions. Recurrent disease is treated with re-resection, temozolomide, lomustine or re-irradiation.

## Fields

- Kind: Cancer
- Last checked: 2026-09-17
- Also known as: Oligodendroglioma; Anaplastic oligodendroglioma; 1p/19q codeleted glioma
- Tags: subtype-page; cns
- Group: central nervous system
- Burden: A small share of adult gliomas, typically found in the frontal lobes of people in their thirties and forties; it has the best outlook of any diffuse adult glioma, with survival often measured in decades.
- Subtypes: Oligodendroglioma, IDH-mutant and 1p/19q-codeleted, grade 2; Oligodendroglioma, IDH-mutant and 1p/19q-codeleted, grade 3 (formerly anaplastic); Oligodendroglioma with minigemistocytes or gliofibrillary oligodendrocytes (morphological variants)
- Biomarkers: IDH1 or IDH2 mutation; Whole-arm 1p/19q codeletion (FISH, array or methylation-based copy number); TERT promoter mutation; CIC and FUBP1 mutations; CDKN2A/B homozygous deletion (shorter survival, rare); DNA methylation class

## Sections of this record

The page is a hub with ten sections in reading order; large sections have their own page. The same plan as JSON: https://onco.cc/api/v1/cancers/oligodendroglioma/sections.json

- Overview (on the hub): The TL;DR, the family this cancer belongs to, the organ, who gets it and what the state of the art is. https://onco.cc/cancers/oligodendroglioma/#overview [3 state-of-the-art points]
- Types and stages (on the hub): Anatomy, the subtypes and how they differ, how it is staged, and where advanced disease spreads. https://onco.cc/cancers/oligodendroglioma/#what-it-is [3 subtypes]
- Symptoms and diagnosis (on the hub): How this cancer shows itself, how the diagnosis is confirmed, and the biomarkers clinicians test for. https://onco.cc/cancers/oligodendroglioma/#finding-it [6 biomarkers]
- Treatment (on the hub): The standard of care by setting, the medicines, surgery and radiotherapy named in it, and the regimens behind them. https://onco.cc/cancers/oligodendroglioma/#treating-it [4 settings, 3 decisions with options]
- Trials and papers (on the hub): Trials recruiting now, the landmark trials, the trials held by this cancer's subtypes, the key papers and what they mean, the latest literature, and the milestones year by year. https://onco.cc/cancers/oligodendroglioma/#evidence [6 trials, 5 key papers, 8 milestones]
- Biology and targets (on the hub): The molecular landscape: the targets and how often each appears, the pathways, the mechanics stages and the preclinical models. https://onco.cc/cancers/oligodendroglioma/#science [2 targets, 1 pathway]
- Countries and centres (own page): Cases by country, the UK and NHS pathway and other country lenses, the expert centres with trials on record, and the centres named on this cancer's subtypes. https://onco.cc/cancers/oligodendroglioma/where-you-are/
- Decisions and support (on the hub): The decisions you may face, the aids that walk through them, the warnings on record, the first sixty days and the questions to ask. https://onco.cc/cancers/oligodendroglioma/#living-with-it [18 questions, 6 red cards]
- Pipeline and open problems (own page): Everything in development, the medicines held by this cancer's subtypes, the open problems and what is being done about them, the roadmaps, and what changed on this record. https://onco.cc/cancers/oligodendroglioma/coming/ [7 medicines, 6 trials, 4 open problems]
- Data (own page): Every connected record, the notes, the JSON, Markdown and RDF twins, and where the record came from and when it was checked. https://onco.cc/cancers/oligodendroglioma/data/ [44 connected records]

## Standard of care

- Newly diagnosed: Maximal safe resection and molecular diagnosis with 1p/19q testing; observation is reasonable after gross total resection of a grade 2 tumour in a younger patient. ([Extent of resection (RANO resect classes)](https://onco.cc/terms/extent-of-resection/), [DNA methylation profiling](https://onco.cc/technologies/methylation-profiling/), [Active surveillance](https://onco.cc/technologies/active-surveillance/))
- Grade 2, residual or recurrent, not needing radiotherapy: Vorasidenib (INDIGO) or continued observation. ([Vorasidenib](https://onco.cc/drugs/vorasidenib/), [INDIGO](https://onco.cc/trials/indigo/))
- Grade 2, high risk, and grade 3: Radiotherapy followed by PCV (procarbazine, lomustine, vincristine), the regimen validated in RTOG 9402, EORTC 26951 and RTOG 9802; radiotherapy with temozolomide is an alternative being compared in CODEL. ([IMRT / IGRT (modern external beam)](https://onco.cc/technologies/imrt-igrt/), [Procarbazine](https://onco.cc/drugs/procarbazine/), [Lomustine (CCNU)](https://onco.cc/drugs/lomustine/), [Vincristine](https://onco.cc/drugs/vincristine/), [RTOG 9402](https://onco.cc/trials/rtog-9402/), [EORTC 26951](https://onco.cc/trials/eortc-26951/), [Temozolomide](https://onco.cc/drugs/temozolomide/))
- Recurrence: Re-resection, temozolomide or lomustine, re-irradiation; bevacizumab for symptoms. ([Temozolomide](https://onco.cc/drugs/temozolomide/), [Lomustine (CCNU)](https://onco.cc/drugs/lomustine/), [Re-irradiation](https://onco.cc/terms/re-irradiation/), [Bevacizumab (glioblastoma use)](https://onco.cc/drugs/bevacizumab-glioma/))

## State of the art

- Oligodendroglioma was the first brain tumour in which a chromosomal marker predicted benefit from chemotherapy, fifteen years before the trials confirmed it.
- Radiotherapy plus PCV roughly doubled survival in codeleted tumours and is still the standard for grade 3 disease.
- Vorasidenib gives grade 2 patients a drug option before radiotherapy for the first time.

## Open problems

- Whether temozolomide can replace PCV without losing survival (CODEL).
- How to sequence vorasidenib, chemotherapy and radiotherapy over a disease course of decades.
- Late cognitive effects of radiotherapy in long survivors.
- No effective treatment for the rare tumours that acquire CDKN2A/B loss or hypermutation.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Oligodendroglioma
- Wikipedia: https://en.wikipedia.org/wiki/Oligodendroglioma
- RTOG 9402 long-term results (JCO 2013): https://doi.org/10.1200/JCO.2012.43.2674
- EORTC 26951 long-term results (JCO 2013): https://doi.org/10.1200/JCO.2012.43.2229

## Connected records

- cancers: [Astrocytoma, IDH-mutant (grades 2 to 4)](https://onco.cc/cancers/idh-mutant-astrocytoma/), [Brain and spinal cord tumours (all types)](https://onco.cc/cancers/brain-tumours/), [Diffuse midline glioma, H3 K27-altered (including DIPG)](https://onco.cc/cancers/dipg-dmg/), [Glioma & glioblastoma](https://onco.cc/cancers/glioblastoma/), [Paediatric high-grade glioma (excluding diffuse midline glioma)](https://onco.cc/cancers/paediatric-high-grade-glioma/), [Paediatric low-grade glioma](https://onco.cc/cancers/paediatric-low-grade-glioma/)
- technologies: [Active surveillance](https://onco.cc/technologies/active-surveillance/), [DNA methylation profiling](https://onco.cc/technologies/methylation-profiling/), [IMRT / IGRT (modern external beam)](https://onco.cc/technologies/imrt-igrt/)
- terms: [1p/19q codeletion](https://onco.cc/terms/1p19q-codeletion/), [CDKN2A/B homozygous deletion](https://onco.cc/terms/cdkn2a-homozygous-deletion/), [Extent of resection (RANO resect classes)](https://onco.cc/terms/extent-of-resection/), [Re-irradiation](https://onco.cc/terms/re-irradiation/)
- targets: [IDH1 / IDH2](https://onco.cc/targets/idh/)
- drugs: [Bevacizumab (glioblastoma use)](https://onco.cc/drugs/bevacizumab-glioma/), [Lomustine (CCNU)](https://onco.cc/drugs/lomustine/), [Procarbazine](https://onco.cc/drugs/procarbazine/), [Safusidenib](https://onco.cc/drugs/safusidenib/), [Temozolomide](https://onco.cc/drugs/temozolomide/), [Vincristine](https://onco.cc/drugs/vincristine/), [Vorasidenib](https://onco.cc/drugs/vorasidenib/)
- pathways: [Glioma (KEGG map)](https://onco.cc/pathways/glioma-signalling/)
- trials: [CODEL](https://onco.cc/trials/codel/), [EORTC 22033-26033](https://onco.cc/trials/eortc-22033/), [EORTC 26951](https://onco.cc/trials/eortc-26951/), [INDIGO](https://onco.cc/trials/indigo/), [Phase II Study of Carmustine, Streptozocin, and Mercaptopurine for Refractory or Recurrent Brain Neoplasms](https://onco.cc/trials/nct00004688/), [RTOG 9402](https://onco.cc/trials/rtog-9402/)
- key papers: [EORTC 26951: adjuvant PCV after radiotherapy for anaplastic oligodendroglial tumours, long-term follow-up](https://onco.cc/key-papers/paper-eortc-26951-van-den-bent-jco-2013/), [INDIGO: vorasidenib, the first targeted drug for IDH-mutant low-grade glioma](https://onco.cc/key-papers/paper-indigo-nejm-2023/), [RTOG 9402: PCV chemotherapy before radiotherapy for anaplastic oligodendroglioma, long-term results](https://onco.cc/key-papers/paper-rtog-9402-cairncross-jco-2013/), [RTOG 9802: radiation plus procarbazine, lomustine and vincristine in high-risk low-grade glioma](https://onco.cc/key-papers/paper-rtog-9802-buckner-nejm-2016/), [The 2021 WHO classification of tumours of the central nervous system: a summary](https://onco.cc/key-papers/paper-who-2021-cns-louis-neuro-oncology-2021/)
- people: [Jan C. Buckner](https://onco.cc/people/jan-buckner/)
- biomarkers: [1p/19q codeletion](https://onco.cc/biomarkers/1p19q-codeletion-readout/), [IDH1 R132 mutation](https://onco.cc/biomarkers/idh1-r132/), [IDH2 mutation (R140 and R172)](https://onco.cc/biomarkers/idh2-mutation/)

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JSON: https://onco.cc/api/v1/entities/oligodendroglioma.json