What is the recommended diagnostic work‑up and treatment plan for patients with gliomas, including management of different WHO grades?

Management of Gliomas: Diagnostic Work-Up and Treatment by WHO Grade

Maximum safe surgical resection is the cornerstone of glioma management across all grades, followed by molecular characterization to guide adjuvant therapy decisions based on IDH mutation status and 1p/19q codeletion. 1

Diagnostic Work-Up

Initial Imaging

• Brain MRI with and without gadolinium-based contrast is the diagnostic gold standard, including T2-weighted, FLAIR, and 3D T1-weighted sequences 1
• Perfusion MRI and amino acid PET can identify metabolic hotspots for targeted tissue sampling, particularly useful when biopsy is planned over open resection 1

Clinical Assessment

• Document Karnofsky Performance Status (KPS), neurological function, and age—these directly influence treatment decisions 1
• Use NANO scale for standardized neurological examination documentation 1
• Perform neurocognitive screening with MMSE or MoCA 1

Molecular Characterization (Essential)

The 2021 WHO classification requires molecular profiling to guide treatment:

• IDH1/IDH2 mutation status (by immunohistochemistry and gene sequencing)
• 1p/19q codeletion status (distinguishes oligodendrogliomas from astrocytomas)
• MGMT promoter methylation (predicts temozolomide benefit in glioblastoma)
• CDKN2A/B homozygous deletion (upgrades IDH-mutant astrocytomas to grade 4) 1

Treatment by Molecular Subtype and Grade

IDH-Mutant Astrocytoma, WHO Grade 2

Surgical Approach:

• Maximum safe resection whenever feasible 1
• Younger patients (<40-45 years) who are asymptomatic or have seizures only can be observed after gross total resection 1

Adjuvant Treatment for High-Risk Patients (age ≥40 years or incomplete resection):

• Radiotherapy (50-54 Gy in 1.8-2 Gy fractions) followed by PCV chemotherapy (procarbazine, lomustine, vincristine) 1
• This regimen extends overall survival from 7.8 to 13.3 years based on RTOG 9802 1

At Progression:

• Temozolomide or nitrosourea chemotherapy 1

IDH-Mutant Astrocytoma, WHO Grade 3

Standard Treatment:

• Radiotherapy (54-60 Gy in 1.8-2 Gy fractions) followed by maintenance temozolomide 1
• This is based on the CATNON trial showing survival benefit with maintenance temozolomide in IDH-mutant grade 3 gliomas 1

At Progression:

• Nitrosourea or temozolomide rechallenge 1

IDH-Mutant, 1p/19q-Codeleted Oligodendroglioma, WHO Grade 2

For Patients Requiring Treatment:

• Radiotherapy (50-54 Gy in 1.8-2 Gy fractions) followed by PCV chemotherapy 1
• Watch-and-wait is acceptable after gross total resection in select patients 1

At Progression:

• Temozolomide 1

IDH-Mutant, 1p/19q-Codeleted Oligodendroglioma, WHO Grade 3

Standard Treatment:

• Radiotherapy (54-60 Gy in 1.8-2 Gy fractions) followed by PCV chemotherapy 1
• Based on EORTC 26951 and RTOG 9402 trials showing median survival of approximately 14 years 1

At Progression:

• Temozolomide 1

IDH-Wild-Type Glioblastoma, WHO Grade 4

For Patients <70 Years with Good KPS:

• Gross total resection whenever feasible 1
• Concurrent chemoradiotherapy: Radiotherapy (60 Gy in 1.8-2 Gy fractions) with daily temozolomide (75 mg/m²) throughout radiotherapy, followed by 6 cycles of maintenance temozolomide (150-200 mg/m², days 1-5 of 28-day cycles) 1

For Patients ≥70 Years:

• If MGMT promoter methylated: Temozolomide chemoradiotherapy or temozolomide alone 1
• If MGMT promoter unmethylated: Hypofractionated radiotherapy alone (40 Gy in 15 fractions) 1
• Patients with good KPS (≥70) benefit from radiotherapy over best supportive care 1

At Progression:

• Nitrosourea, temozolomide rechallenge, or bevacizumab 1
• Re-resection should be considered if gross total resection is achievable 1

Critical Surgical Considerations

Extent of Resection:

• Maximum safe resection improves overall survival across all glioma grades 1
• Use intraoperative MRI or ultrasound to maximize extent of resection 2
• Awake craniotomy with intraoperative mapping for tumors in eloquent cortex 2
• Functional MRI and DTI preoperatively to decrease surgical morbidity 2

Important Caveat: 5-ALA fluorescence-guided surgery is NOT recommended for WHO grade 2 gliomas (insufficient fluorescence) 2

Follow-Up Protocol

• Neurological examination and MRI every 3-6 months 1
• Be alert for pseudoprogression in the first months after radiotherapy—increased imaging abnormalities may not represent true progression 1

Key Pitfalls to Avoid

1. Do not treat IDH-wild-type grade 2/3 astrocytomas the same as IDH-mutant tumors—these are heterogeneous and many harbor molecular features of glioblastoma requiring more aggressive treatment 1

2. MGMT promoter methylation testing is essential for elderly glioblastoma patients to guide treatment selection between radiotherapy alone versus combined modality treatment 1

3. PCV, not temozolomide, is the standard chemotherapy for oligodendrogliomas based on level II evidence from EORTC 26951 and RTOG 9402 1

4. Extending temozolomide maintenance beyond 6 cycles does not improve survival 1

5. Tumor-treating fields remain controversial despite phase III data and are not widely available in Europe 1