What is the best course of treatment for a patient diagnosed with a meningioma?

Treatment of Meningioma

For newly diagnosed meningiomas, complete surgical resection remains the definitive treatment when achievable with minimal morbidity, while observation is appropriate for small asymptomatic lesions, and radiation therapy (stereotactic radiosurgery or fractionated radiotherapy) serves as either primary treatment for surgically inaccessible tumors or adjuvant therapy for incompletely resected or higher-grade lesions. 1, 2, 3

Initial Treatment Algorithm

Asymptomatic Small Meningiomas (<30 mm)

• Observation with serial MRI surveillance every 6-12 months is the recommended approach for asymptomatic small meningiomas, particularly in elderly patients, those with significant comorbidities, or tumors in eloquent/deep locations 1, 4, 3
• Surgery should be considered if the tumor demonstrates growth on serial imaging, becomes symptomatic, or is accessible with acceptable surgical risk 1, 2
• The preservation of neurological function and quality of life takes priority over complete tumor resection 2

Symptomatic Meningiomas or Large Tumors

• Complete surgical resection including removal of the involved dura is the treatment of choice when feasible with minimal or no morbidity 1, 5, 2, 3
• Modern surgical techniques including image-guided surgery (frameless stereotaxy) and intraoperative neurophysiological monitoring improve precision and reduce surgical complications 2
• For posterior fossa meningiomas with significant mass effect and brainstem compression, surgical resection via infratentorial craniotomy or craniectomy is indicated 5

Radiation Therapy Indications

Primary Radiation Therapy

• Stereotactic radiosurgery (SRS) is appropriate as primary treatment for small to moderate-sized tumors in surgically inaccessible locations, high-risk patients, or those wishing to avoid invasive treatment 2, 4, 3
• Fractionated radiotherapy is indicated for larger tumors where SRS is not feasible due to size or proximity to dose-limiting organs 6, 4

Adjuvant Radiation Therapy

• External beam radiation therapy (EBRT) is indicated for WHO grade 3 (malignant) meningiomas after surgery 1, 6
• EBRT is also indicated for subtotally resected WHO grade 2 (atypical) meningiomas 1, 6
• For incompletely resected WHO grade 1 meningiomas, radiation therapy should be considered based on tumor location, patient age, and life expectancy 6, 3

Advanced Treatment Options for Refractory Disease

Peptide Receptor Radionuclide Therapy (PRRT)

• PRRT using radiolabeled somatostatin receptor ligands should be considered for meningiomas progressing after multiple prior lines of treatment when other local therapy options (surgery, radiotherapy) are no longer applicable 7, 1
• SSTR-directed PET imaging must confirm positive expression of SSTR type 2 receptors before initiating PRRT 7
• PRRT remains investigational and should ideally be performed within clinical trials when feasible 7

PRRT Eligibility Criteria

• Karnofsky performance status above 60% or ECOG 0-2 7
• GFR ≥40 ml/min/1.73 m² 7
• Adequate bone marrow function: WBC ≥3,000/μl with ANC ≥1,000/μl, platelets ≥75,000/μl, RBC ≥3,000/μl 7
• Adequate hepatic function: total bilirubin <3× upper limit of normal, albumin ≥30 g/l, INR <1.5 7
• Brain MRI within 2 weeks prior to PRRT as baseline 7

PRRT Treatment Regimen

• Standard regimen consists of 4 treatment cycles spaced 8±2 weeks apart, adapted from neuroendocrine tumor protocols 7
• Acute side effects include nausea (4%), vomiting (7%), and lymphopenia (9%), which are generally clinically manageable 7
• Antiepileptic drugs should be prescribed for acute post-treatment seizures 7, 8
• Corticosteroids should be prescribed for signs of intracranial hypertension 7, 8

Pharmacotherapy for Refractory Meningiomas

• Medical therapy has limited efficacy and is reserved for inoperable, radiation-refractory meningiomas 9
• Hydroxyurea, interferon-α, and somatostatin analogues (Sandostatin LAR) are the only recognized medical therapies, though results have been modest 4, 9
• Targeted therapies directed at PDGF, EGF, and VEGF pathways have shown limited success with significant toxicity 9

Diagnostic Imaging Requirements

Initial Diagnosis

• MRI with contrast is the gold standard for meningioma evaluation, demonstrating homogeneous dural-based enhancement, dural tail sign, and CSF cleft between tumor and brain 1
• CT can detect larger meningiomas with calcifications but is significantly inferior to MRI and frequently misses small lesions 1

Advanced Imaging

• SSTR-directed PET imaging should be obtained when tumor extension or diagnosis of recurrence is unclear 7, 1
• SSTR PET is particularly useful for differentiating meningioma recurrence from treatment-related changes (radionecrosis/scar) 7, 1
• SSTR PET is essential for patient/lesion selection for PRRT eligibility and response assessment 7

Critical Management Pitfalls

• Do not assume all enhancing dural-based lesions are meningiomas—metastases, gliomas, and primary CNS lymphoma can present similarly 8, 1
• Do not underestimate potential for significant intraoperative blood loss, particularly with large hemispheric or intraventricular tumors 8, 1
• Do not overlook the need for specialized neurosurgical expertise for skull base, cavernous sinus, or intraventricular locations 8, 1
• Avoid relying on CT alone for excluding meningioma, as negative CT does not rule out the diagnosis 1

Acute Complications Management

Post-PRRT Complications

• Hydrate with normal saline and repeat antiemetic administration for metabolic acidosis-related nausea and vomiting 7, 8
• Monitor for acute seizures and intracranial hypertension as specific post-PRRT complications 7, 8
• Maintain awareness of potential symptomatic edema or radionecrosis as delayed presentations 8

General Acute Changes

• Administer dexamethasone to reduce peritumoral edema in patients with significant mass effect or neurological symptoms 8
• Immediate neurosurgical consultation is required for progressive neurological deterioration, declining Glasgow Coma Scale, or signs of herniation 8

Surveillance Strategy

• For WHO grade 1 meningiomas, perform MRI with contrast every 6-12 months 1
• SSTR PET may be useful in distinguishing tumor recurrence from post-treatment changes during surveillance 1
• Recurrence rates for completely resected benign meningiomas can reach 20% within 25 years, necessitating long-term follow-up 1