Meningioma

Updated by Mark Edson

BACKGROUND

What % of all primary CNS tumors do meningiomas account for in adults?

34%. Meningioma is the most common benign 1^st-degree CNS tumor. (Central Brain Tumor Registry of the United States, 2012 update). Autopsy studies suggest prevalence of subclinical meningiomas in up to 3% of the general population.

What are the age and sex predilection for meningiomas?

Meningiomas appear late in life (mean age at Dx 62, incidence peaks in the 8^th decade). Females are more commonly affected than males (2:1).

What are some risk factors for meningiomas?

Prior RT (RR 10, median interval to development 20 yrs), NF-2, and HRT in women (RR 2).

Which protein is defective in NF-2, and to what else does NF-2 predispose?

Merlin; bilat acoustic neuromas/ependymomas and juvenile subcapsular cataracts

What histologic features can be seen in meningiomas?

Psammoma bodies and calcifications

List 5 negative prognostic factors for meningiomas.

Negative prognostic factors for meningiomas:

1. High grade

2. Young age

3. Chromosome alterations

4. Poor performance status

5. STR

What is the grade classification of meningiomas?

WHO grade I (benign), grade II (atypical), and grade III (anaplastic/malignant).

According to the 2007 WHO classification, what criterion upgrades an otherwise grade I meningioma to grade II?

Brain invasion.

What is the prevalence of grades II–III meningiomas?

6% and 4%, respectively. 90% are grade I.

Name the histologies associated with WHO grades II–III meningiomas.

Grade II: atypical, clear cell, chordoid

Grade III: anaplastic, rhabdoid, papillary

Of grade I meningiomas, which histologic subtype is most aggressive?

The angioblastic subtype is the most aggressive grade I meningioma.

What is the OS difference between atypical and anaplastic meningiomas?

Atypical 12 yrs vs. anaplastic 3.3 yrs (Yang SY et al., J Neurol Neurosurg Psychiatry 2008)

What are some prognostic factors identified for anaplastic meningiomas?

Brain invasion, adj RT, extent of resection, and p53 overexpression (Yang SY et al., J Neurol Neurosurg Psychiatry 2008)

WORKUP/STAGING

What is the most common Sx at presentation for meningiomas?

HA is the most common presenting Sx.

What is the appearance of meningiomas on CT/MRI?

Homogeneously and intensely enhancing mass, +/– dural tail

What % of meningiomas exhibit a dural tail? In what other tumors/lesions can dural tails be seen?

60%. Dural tails can also be seen in chloroma, lymphoma, and sarcoidosis.

What proportion of incidentally found meningiomas remain stable on imaging?

Two-thirds. The majority remain stable on imaging.

For meningiomas, with what are slower growth rates associated?

Slower growth rates are associated with older pts and calcifications.

What surgical grading system is used in meningiomas? For what does it predict?

Simpson grade (I/GTR–V/decompression) predicts the likelihood of LR.

In what anatomic regions is GTR more difficult to achieve for meningioma resection?

Cavernous sinus, petroclival region, postsagittal sinus, and optic nerve.

How is optic sheath meningioma diagnosed?

Optic sheath meningioma is diagnosed clinically/radiographically by a neuro-ophthalmologist/MRI (no Bx).

TREATMENT/PROGNOSIS

What are the Tx paradigms for meningiomas?

Meningioma Tx paradigms:

If incidental/asymptomatic: observation

If grade I and symptomatic/progressive: surgery +/– RT

If grade II or III: surgery + RT

For which types of meningioma is RT the primary Tx modality?

Optic nerve sheath and cavernous sinus (inaccessible regions)

When should observation be considered?

Observation should be considered with incidental/asymptomatic and stable lesions. Consider surgery for large (≥30 mm) lesions, if accessible.

When is RT utilized after surgery for meningiomas?

RT should be utilized after surgery if there is recurrent Dz or STR or if there is anaplastic histology or brain invasion.

What is the avg time to recurrence after surgery for meningiomas?

4 yrs is the avg time to recurrence after surgery.

What are the 10-yr recurrence rates with surgery alone after either GTR or STR?

10-yr recurrence rates with surgery alone are ~10% after GTR and 60% after STR.

Is there a benefit to upfront RT after STR for grade I meningioma?

This is controversial (upfront control rates are considered equivalent to salvage rates). RTOG 0539 will attempt to address this question in its low-risk cohort.

What are the RT doses employed for meningiomas?

RT doses are 54 Gy for benign and 60 Gy for malignant tumors (PTV = GTV + 1–2 cm).

Is there any RT dose-response data for meningiomas?

Yes. Goldsmith BJ et al. showed improved PFS with doses >52 Gy. (J Neurosurg 1994)

What are typical SRS doses used for meningiomas?

Typical SRS doses range from 12–16 Gy to 50% IDL at the tumor margin (depending on location/size).

What is the 5-yr LC rate for meningiomas after SRS?

The 5-yr LC rate is ~95% for grade I tumors. For grades II–III, it is 68% and 0%, respectively. (Stafford SL et al., Neurosurgery 2001)

What poor prognostic factors have been identified in pts receiving SRS for meningiomas?

Male sex, previous surgery, tumors located in parasagittal/falx/convexity regions (Pollock BE et al., Neurosurgery 2012)

Should the dural tail be covered in the RT field?

In general, no; however this is controversial. Some studies have shown improved 5-yr DFS when the dural tail was included in SRS prescription isodose. (DiBiase SJ et al., IJROBP 2004)

TOXICITY

What is the surgical complication rate after resection for meningiomas?

After resection, the surgical complication rate is 2%–30% depending on the location/type; 1%–14% mortality (worse in the elderly).

If observed, pts should get MRIs at what intervals?

At 3 mos, 6 mos, and 12 mos, then every 6–12 mos for 5 yrs, then every 1–3 yrs if stable

What is the toxicity rate for SRS if doses >16 Gy are used?

There is temporary toxicity in 10% of pts and permanent toxicity in 6% of pts. Perilesional edema is observed in 15%. (Kullova A et al., J Neurosurg 2007)

What is the RT dose limitation to the chiasm when SRS is used?

The chiasm should be limited to 8 Gy with SRS.

How are optic nerve sheath/cavernous sinus meningioma pts followed?

These pts should be followed with serial MRIs, neuro-ophthalmology exams, and regular endocrinology exams.

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