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MAWRIN, CHUNG, AND PREUSSER
grade and have annual growth rates of 1 to 3 mm per year. 99 If
an observational approach is taken, close follow-up with serial
imaging and clinical neurologic assessment is required to
avoid overlooking the development of symptoms that suggest
more rapid tumor growth. If tumor growth is documented
or if clinical symptoms develop or progress,
discussion about treatment should be revisited.
SURGERY
The usual initial treatment is surgical excision of the tumor
and its dural base, particularly for tumors located on the
outer brain surface and surgically easily accessible. After
gross total resection (i.e., complete excision of the tumor and
its dural attachments) of a benign meningioma, the risk of
tumor recurrences are 5%, 10%, and 30% at 5, 10, and 15
years, respectively. 100 The extent of surgery is reported by
Simpson grade. Sughrue et al 101 reported that, for patients
who have grade 1 meningioma, the extent of resection impacts
the risk of recurrence and progression-free survival. After
Simpson grade 1, 2, 3, and 4 resections, the respective
5-year progression-free survival rates were 95%, 85%, 88%,
and 81%. 101
Not all meningiomas can be totally resected without an unacceptable
risk of postoperative neurologic defıcits. For skullbased
meningiomas, a particular surgical risk is cranial nerve
palsy. 102-104 Newer microsurgical and endoscopic techniques
in combination with advances in neuroimaging have improved
the outcomes of surgical resection of meningiomas.
105,106 Finally, there has been a move toward optimizing
functional preservation by utilizing a combination of the currently
available surgical and radiotherapy techniques personalized
to the patient and particular clinical situation over
achieving radical resections that results in functional loss.
RADIOTHERAPY
The role of radiotherapy in the management of meningiomas
depends on patient factors, such as their comorbidities and
preference, and on tumor factors, including tumor size, resectability,
and—particularly—grade. Radiotherapy also is
usually recommended for recurrent meningiomas after initial
surgical resection, either as monotherapy or as adjuvant
therapy after reresection. 107
In general, radiotherapy is recommended after surgical resection
of malignant (WHO grade 3) meningiomas because
of the considerably better 5-year progression-free survival
seen with surgery followed by adjuvant radiotherapy (80%)
compared with surgery alone (15%). 108 Radiotherapy was
shown to shrink any remaining tumor burden in addition to
preventing tumor recurrence. 109,110
For atypical (WHO grade 2) meningiomas, the optimal
timing of radiotherapy is less clear, particularly after a complete
resection. Retrospective studies have demonstrated that
early adjuvant radiotherapy for nonbenign meningiomas improves
progression-free survival, but the majority of these
studies have evaluated grade 2 and 3 meningiomas together,
and the benefıt may reflect selection bias of higher risk cases
to receive adjuvant radiotherapy versus those that did not receive
radiotherapy postoperatively. 108,111-113 As the goals of
treatment shift toward optimizing functional outcome and
minimizing treatment-related toxicity, close observation is
typically preferred after a gross total resection of a grade 2
meningioma. After an incomplete resection or at the time of
tumor recurrence, radiotherapy options, including potential
radiosurgery or fractionated radiotherapy, are offered, depending
on the volume and location of the tumor. 114
For WHO grade 1 meningiomas, there is even greater controversy
about the optimal management, because there are a
greater number of management options, including observation,
radiosurgery alone, fractionated radiotherapy alone,
surgical resection alone, or a combination of surgery with
postoperative radiosurgery or fractionated radiotherapy. After
surgical resection, there is controversy about early postoperative
radiotherapy versus delayed radiotherapy at the
time of tumor recurrence. Data support the improved local
control of early adjuvant radiotherapy compared with surgery,
particularly after partial resection. 115 In contrast, a delay
in radiotherapy until tumor recurrence can help spare
radiotherapy and its associated toxicities in a proportion of
patients who do not experience tumor recurrence. 116
Radiosurgery
Radiosurgery can be delivered with a variety of devices, including
the Gamma Knife, Cyberknife, and a linear accelerator
(LINAC). A single fraction to a marginal dose of 10 to 15
Gy is usually given. 117,118 Because treatment of a larger target
volume results in greater treatment-related toxicity, radiosurgery
typically is offered to tumors that are smaller volume
and not in very close proximity to critical structures, such as
the optic chiasm. 119 In a multicenter study of 254 patients
treated up front for petroclival meningioma with radiosurgery
(140 patients) or with radiosurgery after surgery (144
patients), the actuarial progression-free survival rates were
93% and 84% at 5 and 10 years, respectively. 120 Similar tumor
control, with actuarial 5- and 10-year progression-free survival
rates of 95% and 92%, respectively, has been reported
for sellar and parasellar meningiomas treated with a singlefraction
radiosurgery treatment to a median prescription
dose of 13 Gy (range, 5 to 30 Gy). 121
Fractionated Radiotherapy
Fractionated radiotherapy is often delivered with stereotactic
radiotherapy (SRT) or image-guided radiotherapy approaches
to optimize the precision of radiotherapy delivery
in combination with intensity-modulated radiotherapy techniques
to improve the dose shaping around complex targets
in close vicinity to critical normal structures. For benign meningiomas,
fractionated radiotherapy is offered for large volume
tumors or those in very close proximity to critical
structures, such as the optic chiasm. The volume that is targeted
for benign tumors is typically the enhancing tumor,
with a minimal margin for set-up error. The radiation dose
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