Loading
9 slides generated from the cancer page, with a quiz from the open benchmark and speaker notes that cite the sources. Arrow keys move between slides; Print gives one slide per page.
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.
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.
| Setting | Approach | Guideline |
|---|---|---|
| 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. | not mapped |
| Grade 2, residual or recurrent, not needing radiotherapy | Vorasidenib (INDIGO) or continued observation. | not mapped |
| 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. | not mapped |
| Recurrence | Re-resection, temozolomide or lomustine, re-irradiation; bevacizumab for symptoms. | not mapped |