# Neuro-oncology: Gliomas

> Glioma classification and treatment for NEET-SS Neurology: 2021 WHO molecular groups, Stupp regimen, MGMT methylation and pseudoprogression.

- Canonical URL: https://prepelephant.com/topics/neet-ss/neurology/neuro-oncology-gliomas
- Exam / course: NEET-SS · Subject: Neurology
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-02
- Last updated: 2026-10-02
- How to cite: "Neuro-oncology: Gliomas", PrepElephant, https://prepelephant.com/topics/neet-ss/neurology/neuro-oncology-gliomas

## Direct answer

Glioma classification changed fundamentally in 2021: adult diffuse gliomas are now defined by molecular markers first — IDH-mutant astrocytoma (grades 2-4, with CDKN2A/B homozygous deletion upstaging to grade 4), IDH-mutant and 1p/19q-codeleted oligodendroglioma, and IDH-wildtype glioblastoma, which can be diagnosed even from a low-grade-looking biopsy if it carries TERT promoter mutation, EGFR amplification or the combined +7/-10 chromosome signature. Glioblastoma treatment is the Stupp protocol: maximal safe resection followed by concomitant radiotherapy (60 Gy in 30 fractions) with daily temozolomide 75 mg/m², then six adjuvant cycles of 150-200 mg/m² on 5 days per 28-day cycle. MGMT promoter methylation predicts chemotherapy benefit and longer survival; IDH mutation is the strongest favourable prognostic marker in diffuse gliomas. The neurologist's job spans seizure control, steroid stewardship, recognising pseudoprogression on post-radiotherapy MRI, and honest survival conversations.

## What you must remember

- **The 2021 WHO map:** adult-type diffuse gliomas divide into astrocytoma, IDH-mutant (grades 2-4); oligodendroglioma, IDH-mutant and 1p/19q-codeleted (grades 2-3); glioblastoma, IDH-wildtype (grade 4) — plus paediatric-type entities such as diffuse midline glioma, H3 K27-altered.
- **Molecular upstaging rules:** CDKN2A/B homozygous deletion makes an IDH-mutant astrocytoma grade 4 regardless of histology; TERT promoter mutation, EGFR amplification or +7/-10 makes an IDH-wildtype tumour behave as glioblastoma.
- **Stupp dosing verbatim:** radiotherapy 60 Gy in 30 fractions with temozolomide 75 mg/m² daily throughout, then adjuvant temozolomide starting 150 mg/m² escalating to 200 mg/m², days 1-5 of each 28-day cycle for six cycles.
- **Prognostic hierarchy:** IDH mutation most favourable; MGMT promoter methylation predicts temozolomide responsiveness; 1p/19q codeletion adds chemosensitivity and the best outcomes among diffuse gliomas; age and extent of resection remain clinical anchors.
- **Radiology anchors:** glioblastoma as an enhancing rim-and-necrosis lesion with vasogenic oedema, often crossing the corpus callosum ("butterfly"); lower-grade gliomas as non-enhancing T2/FLAIR lesions, frequently frontal in IDH-mutant disease; perfusion rCBV elevation flags high-grade transformation.
- **Pseudoprogression:** new enhancement within 3-6 months after chemoradiotherapy, especially in MGMT-methylated tumours, mimics progression but stabilises or improves — clinicoradiological judgement, sometimes methionine-PET or biopsy, before changing therapy.
- **Seizure pragmatics:** low-grade gliomas seize frequently — antiseizure drug selection with enzyme-inhibiting interactions in mind (levetiracetam preferred alongside chemotherapy); prophylactic antiepileptics for unreformed seizures are not indicated; steroid (dexamethasone) only for symptomatic oedema, tapered to the lowest dose.

## A pathway from biopsy to adjuvant cycles

A 46-year-old presents with a first generalised seizure; MRI shows a non-enhancing FLAIR lesion in the right frontal lobe with low perfusion. Maximal safe resection returns an IDH-mutant, 1p/19q-intact astrocytoma without CDKN2A/B deletion — grade 2 — and management is observation with serial imaging versus radiotherapy-plus-temozolomide decided by risk factors (age over 40, incomplete resection push toward treatment), because low-grade does not mean benign. Contrast the 62-year-old whose left temporal enhancing ring lesion resects as IDH-wildtype glioblastoma, MGMT-methylated: Stupp protocol begins, and at the three-month post-radiotherapy scan the enhancement has grown — but the patient is clinically better, and methionine-PET shows low uptake: pseudoprogression, so adjuvant cycles continue, and the next scan plateaus. The skills being exercised are the exam's actual questions: naming the molecular diagnosis from the marker panel, writing the Stupp doses from memory, and refusing to call progression without weighing pseudoprogression, radionecrosis and steroid effect.

## Where candidates slip

The recurring gaps: quoting histology-only grades (a "grade 2" IDH-wildtype tumour with +7/-10 is glioblastoma — the molecular rule overrides); forgetting that oligodendroglioma requires both IDH mutation and 1p/19q codeletion (1p/19q loss alone means nothing without IDH); and mismanaging the post-treatment scan by starting second-line chemotherapy for pseudoprogression. The Indian practice note: generic temozolomide is widely available and affordable, but comprehensive molecular panels (IDH, ATRX, TERT, EGFR, 1p/19q, MGMT) are variable in cost and turnaround outside metropolitan centres — the examinable corollary is knowing the minimum viable panel: IDH mutation and 1p/19q status change the diagnosis, MGMT changes the conversation.

## Frequently asked questions

### Which molecular markers define glioblastoma, IDH-wildtype?

TERT promoter mutation, EGFR amplification, or combined chromosome +7/-10 — any one in an IDH-wildtype diffuse astrocytic tumour establishes glioblastoma even without grade 4 histology.

### What is the complete Stupp regimen?

Maximal safe resection, then 60 Gy radiotherapy in 30 fractions with concomitant temozolomide 75 mg/m² daily, followed by six adjuvant 5-day cycles at 150-200 mg/m² every 28 days.

### What does MGMT promoter methylation predict?

Better response to temozolomide and longer survival, because methylation silences the repair enzyme that removes temozolomide-induced DNA damage.

### Which genetic combination defines oligodendroglioma?

IDH mutation plus 1p/19q codeletion — the combination that confers chemosensitivity and the best prognosis among diffuse gliomas.

### What is pseudoprogression and how is it recognised?

New or increased enhancement within months of chemoradiotherapy that stabilises or improves without treatment change, more frequent with MGMT-methylated tumours — a clinicoradiological or PET-supported judgement.