How do you manage a patient with residual meningioma tumor after 1 year of tumor resection?

Management of Residual Meningioma After Tumor Resection

Stereotactic radiosurgery (SRS) is the recommended treatment for residual meningioma detected one year after initial tumor resection, as it provides excellent tumor control with minimal complications. 1

Diagnostic Evaluation

• MRI without and with IV contrast is the standard imaging modality for evaluating residual meningioma, with recommended follow-up intervals based on WHO tumor grade 1
• For WHO grade 1 meningiomas, MRI surveillance should be performed every 6-12 months 1, 2
• Somatostatin receptor (SSTR) PET imaging should be obtained if tumor extension is unclear or to differentiate recurrence from treatment-related changes 1
• SSTR PET/CT or PET/MRI provides more accurate delineation of residual tumor extent, particularly for WHO grade 2 and 3 tumors 1

Treatment Algorithm for Residual Meningioma

For WHO Grade 1 Residual Meningioma:

• SRS is the preferred treatment option with 5-year progression-free survival (PFS) rates ranging from 86% to 99% 1
• SRS offers higher rates of tumor shrinkage compared to fractionated stereotactic radiotherapy (SRT) (53% vs 29%, p<0.04) 1
• Post-SRS neurological preservation rates range from 80% to 100% 1
• Tumor typically stabilizes after SRS, with 95% achieving steady state by 5 years and 90% by 10 years 1

For WHO Grade 2-3 Residual Meningioma:

• More frequent MRI surveillance is necessary (every 3-4 months for grade 3) 3
• Consider hypofractionated SRT for larger residual tumors or those with pre-existing edema to minimize complications 1
• SSTR PET imaging is particularly valuable for assessing response to radiotherapy in higher-grade meningiomas 1
• For treatment-refractory cases with positive SSTR expression, peptide receptor radionuclide therapy (PRRT) may be considered 1

Follow-up Protocol After Treatment

• For completely resected WHO grade 1 meningiomas with no residual tumor, annual MRI can be discontinued if there is no recurrence after 11 years 3
• For residual or incompletely resected meningiomas of any grade, indefinite MRI surveillance is recommended 3
• Routine radiological follow-up can be extended to longer intervals after the tumor has attained a steady state 1
• Clinical follow-up should continue with routine neurological exams and ophthalmological assessment 1

Special Considerations

• Re-radiosurgery may be considered for recurrent residual tumor after initial SRS, particularly for benign (WHO grade 1) meningiomas 4
• WHO tumor grade is a significant factor for progression-free survival after re-radiosurgery (p=0.004) 4
• For larger residual tumors or those near critical structures, hypofractionated SRT may have less likelihood of causing post-radiosurgical edema than single-fraction SRS 1
• Residual tumor is best detected on MRI studies obtained within the first 5 days after surgery, as membrane thickness increases by 3-8 weeks post-surgery and may obscure small residual meningioma 5

Treatment Efficacy and Outcomes

• SRS for residual meningioma shows 10-year PFS rates ranging from 69% to 97% 1
• Tumor shrinkage is more common after SRS compared to SRT, though clinical improvement rates are similar 1
• For completely resected WHO grade 1 meningiomas that later recur, the 5-year and 10-year cumulative incidence of recurrence is 10% and 20%, with no recurrences beyond 11 years 3
• For incompletely resected meningiomas of all grades, recurrences can occur throughout the observation period, necessitating indefinite follow-up 3