What the Mayo Clinic said about Meningioma

This comes from the October 2007 Symposium on Solid Tumors.  I have bolded what was interesting to me.

An estimated 43,800 new cases of benign and malignant brain
tumors are diagnosed annually in the United States, including
3410 cases in children and adolescents. Of these patients,
approximately 12,760 will die. The incidence of
brain tumors is 14.8 per 100,000 person-years, with approximately
half being histologically benign. Even benign
tumors, if not amenable to excision or radiation therapy,
can be fatal as a result of progressive growth in the closed
space of the skull. Females have a slightly higher incidence
(15.1/100,000 person-years) than males (14.3/100,000 person-
years), likely because of the higher incidence of meningiomas
in women…

Meningiomas are usually benign and originate in the dura
that covers the brain and spinal cord. The incidence rate for
the tumor is approximately 2 cases per 100,000 individuals.
They are most common for women in the sixth and seventh
decades of life. Loss of chromosome 22 is characteristic of
meningiomas, although the prognostic significance of this
finding is unclear. The frequency of meningioma is increased
for patients with type 2 neurofibromatosis. Although
meningiomas can express receptors for androgen, estrogen,
progesterone, and somatostatin, therapies directed at these
receptors have not yet shown therapeutic efficacy.
Patients with meningiomas may present with features
typical of mass lesions in the brain, including seizures or
focal neurologic deficits. Meningiomas, which may be
asymptomatic, are also detected incidentally on CT or MRI
scans that are obtained for other reasons. The tumors have
a characteristic MRI appearance, usually consisting of uniform
contrast enhancement along the dura, with distinct
separation from the brain parenchyma. Also characteristic,
although not present in all cases, is the “dural tail,” ie,
contrast enhancement extending from the mass lesion.
There may be marked parenchymal edema, which is the
consequence of vascular endothelial growth factor secreted
by the tumor cells, leading to local mass effect.
Many meningiomas that are noted incidentally do not
require treatment at the time of original diagnosis. For
patients with asymptomatic meningioma, observation may
be appropriate. Epidemiological evidence suggests that as
many as two-thirds of these patients will not have symptoms
over time. If substantial mass effect is observed in patients
with or without symptoms, the treatment of choice is usually
complete resection. Surgery is often feasible if the meningioma
is located over the cortical convexity, olfactory
groove, anterior sagittal sinus, or posterior fossa. However,
resection may be more difficult for tumors at other sites, such
as sphenoidal, parasagittal, orbital, tentorial, or clivus locations.
Under those circumstances, external beam radiotherapy
or focal stereotactic radiotherapy may be extremely
useful for tumor control. In a Mayo Clinic study that compared
tumor control rates after surgical resection or SRS for
patients with small- to medium-size intracranial meningiomas
without symptomatic mass effect,36 SRS achieved better
tumor control (98% vs 88%) with fewer complications (10%
vs 22%) than surgical resection. With regard to the choice of
radiotherapy modality, SRS is usually reserved for the
smaller lesions (ie, <3-4 cm), whereas fractionated stereotactic
radiotherapy is used for larger lesions or meningiomas
near critical structures such as the optic nerves. No pharmaceutical
interventions have reproducibly demonstrated antitumor
efficacy for meningiomas.
Rarely, meningiomas may have atypical histologic features
or may be frankly malignant. Meningiomas can be
highly aggressive, and the approach to such tumors is
identical to that for benign meningiomas, although postoperative
radiation is typically delivered.

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