What is the recommended adjuvant treatment for a patient with a meningioma (brain tumor) grade 2 after undergoing a Simpson's (Simpson's grading system for meningioma resection) grade 2 resection?

Adjuvant Radiation Therapy for Grade 2 Meningioma After Simpson Grade 2 Resection

Adjuvant radiation therapy is recommended following Simpson grade 2 resection of WHO grade 2 meningioma to improve local control and reduce the risk of recurrence. 1

Treatment Decision Algorithm

Factors to Consider:

• WHO grade 2 (atypical) meningioma
• Simpson grade 2 resection (complete tumor removal with dural attachment coagulation)
• Risk of recurrence

Recommended Treatment Approach:

1. Adjuvant Radiation Therapy
   • Dose: 45-54 Gy in 1.8-2.0 Gy fractions 1
   • Recommended dose range: 50-54 Gy 1
   • Timing: Within 6 months of surgical resection 2

Evidence Supporting Adjuvant Radiation

The NCCN guidelines specifically state that WHO grade 2 meningiomas may be treated by fractionated conformal radiotherapy with doses of 45-54 Gy 1. For subtotally resected WHO grade 2 meningiomas, radiation therapy should be considered 1.

Recent evidence from a large retrospective cohort study demonstrated that adjuvant radiotherapy is independently associated with a lower chance of recurrence for atypical meningiomas. The mean time to recurrence was significantly longer in patients who received adjuvant RT (43.7 months) compared to those who did not (34.7 months) 2.

Another study showed that adjuvant radiotherapy improves local control for atypical meningiomas even after Simpson Grade I, II, or III resections 3. This study found that the median time to local failure was 180 months with adjuvant radiotherapy compared to only 46 months with surgery alone (p=0.002) 3.

Important Considerations

Prognostic Factors

Poor prognostic factors that strengthen the case for adjuvant radiation include:

• Age > 35-40 years 1
• Low Karnofsky score 1
• Contrast enhancement on MRI 1
• Large tumor volume or mass effect 1
• Involvement of deep structures 1

Potential Alternative Approach

While the weight of evidence favors adjuvant radiation, one recent propensity score-adjusted analysis suggested that observation with salvage radiation at recurrence might be a reasonable alternative after gross total resection 4. However, this study has limitations and the predominant evidence still supports upfront adjuvant radiation for WHO grade 2 meningiomas after Simpson grade 2 resection.

Radiation Planning

• Target volume should include the tumor bed with appropriate margins
• MRI should be used for radiological evaluation and follow-up 1
• Fractionated conformal radiotherapy is the standard approach 1

Follow-up Recommendations

• Regular MRI surveillance to detect potential recurrence
• Clinical evaluation for neurological symptoms
• Long-term follow-up is essential as recurrences can occur years after initial treatment

Pitfalls to Avoid

1. Delaying radiation therapy beyond 6 months after surgery may reduce its effectiveness
2. Inadequate radiation dose (less than 45 Gy) may not provide optimal tumor control
3. Failing to recognize that recurrent disease is more difficult to control than primary disease, underscoring the importance of aggressive initial treatment 3
4. Overlooking the fact that WHO grade 2 meningiomas have significantly higher recurrence rates than grade 1 meningiomas, justifying more aggressive initial management

In summary, the evidence strongly supports the use of adjuvant radiation therapy after Simpson grade 2 resection of WHO grade 2 meningioma to maximize local control and improve outcomes related to morbidity, mortality, and quality of life.