What are the treatment options for recurrent meningioma 2 years after initial treatment, specifically regarding stereotactic radiation therapy (SRT)?

Stereotactic Radiation Therapy for Recurrent Meningioma

Stereotactic radiation therapy (SRT) is highly effective for recurrent meningiomas and should be considered the treatment of choice when complete surgical resection is not feasible or carries significant risk of morbidity. 1

Treatment Algorithm for Recurrent Meningioma

Initial Assessment

• Confirm recurrence with MRI (performed every 2-3 months for the first 1-2 years after initial treatment) 2
• Consider advanced imaging techniques (MR spectroscopy, MR perfusion, or PET) to differentiate tumor recurrence from radiation necrosis 2
• Assess tumor size, location, and proximity to critical structures
• Evaluate patient's performance status and comorbidities

Treatment Options Based on Recurrence Pattern

For Limited Recurrence (1-3 lesions):

1. Surgical Resection

   • Consider if tumor is accessible with minimal risk of morbidity 2
   • Particularly important if causing mass effect or neurological symptoms
   • Complete resection remains the preferred treatment if achievable 1

2. Stereotactic Radiation Therapy

   • For small tumors (<3-3.5 cm): Single-fraction stereotactic radiosurgery (SRS) 1

     • Typical dose: 12-16 Gy to the 50-90% isodose line 3
     • Excellent 5-year tumor control rates >90% 1

   • For larger tumors (>3-3.5 cm): Fractionated stereotactic radiotherapy (SRT) 1

     • Better for tumors near critical structures (optic chiasm, brainstem)
     • Provides equivalent tumor control with potentially lower toxicity for larger volumes

3. Combined Approach

   • Subtotal resection followed by adjuvant SRS/SRT
   • Particularly useful for skull base meningiomas where complete resection is challenging 1

For Multiple Recurrences (>3 lesions):

• Consider whole brain radiation therapy (WBRT) 2
• Standard regimens: 30 Gy in 10 fractions or 37.5 Gy in 15 fractions 2

Efficacy and Outcomes

• Local tumor control rates with SRS/SRT exceed 90% at 5 years for benign meningiomas 1
• Estimated 2-, 5-, and 10-year regional recurrence rates with SRS are 1.5%, 3.0%, and 6.6%, respectively 4
• Tumor regression is observed in approximately 54% of cases within 12-36 months after SRS treatment 5

Potential Adverse Effects

• Early adverse events (≤6 months after SRS) occur in approximately 11% of patients (CTCAE grade 1-2) 4
• Late adverse events occur in about 14% of patients 4
• Risk factors for adverse effects include:
  • Pre-existing neurological deficits
  • Larger treatment volumes
  • Proximity to critical structures

Special Considerations

For Previously Irradiated Patients

• Re-irradiation should only be considered when:
  1. It can be delivered without exceeding dose constraints on organs at risk
  2. Adequate coverage of target volumes can be achieved 2
  3. The patient had a positive response to the first course of radiation 2

For Patients with Poor Performance Status

• Consider hypofractionated radiation therapy regimens 2
• Palliative/best supportive care may be appropriate in some cases

Follow-up Recommendations

• MRI every 2-3 months for the first 1-2 years after treatment 2
• Continue regular imaging beyond 1-2 years for patients with active disease 2
• Be aware that post-treatment changes may mimic progression within the first 3 months after radiation 2

Emerging Options

• For patients with exhausted surgical and radiation options, systemic therapy may be considered in select cases, though evidence is limited 6

SRS and SRT represent highly effective treatment modalities for recurrent meningiomas, providing excellent long-term tumor control with acceptable toxicity profiles. The choice between these techniques should be based on tumor size, location, and proximity to critical structures.