A Brain Tumor Primer: Common Tumors and Presentation
Pankaj A. Gore, M.D.
Neurosurgeon and medical director,
Brain tumor and skull base surgery
Providence Brain and Spine Institute
How brain tumors present is significantly
related to their location, size and rate of
growth. Tumors associated with the
pituitary gland can manifest endocrine
effects related to pituitary hypofunction
or hyperfunction, for example, while many
slow-growing tumors, such as meningiomas and pituitary
tumors, may be discovered incidentally upon unrelated
Generally MR imaging should be ordered for any new,
persisting or dramatically changed headache, any
subacute progressive neurologic deficit (motor, sensory,
visual, cognitive or cranial nerve) or new seizure. In a
patient with history of systemic cancer, the threshold for
obtaining imaging in the setting of a new headache is even
lower. Sudden onset, severe headache should prompt an
urgent referral to the emergency room.
Meningiomas account for approximately
30 percent of intracranial
neoplasms. They arise from the
arachnoid cap cells of the meninges.
More than 90 percent of these
tumors tend to be benign, with the
remainder falling into atypical
(7 percent) and malignant (2 percent)
Meningiomas typically grow at 1-2
mm/year. Tumors less than 2 cm in
size tend to be asymptomatic, but
this is heavily dependent on location.
Stable, asymptomatic lesions or slowgrowing
tumors in patients over 70
years old are typically followed with
Surgical resection is the first line
of treatment in healthy patients.
Gamma Knife radiosurgery can
be utilized for tumors smaller than
10 cm3, for patients with a higher
risk of surgical morbidity or for
control of postoperative residual or
recurrence. External beam radiation
is usually reserved for postoperative
unresectable residual or recurrence
that is too large for Gamma Knife.
Patients who are postresection of
a meningioma need to be followed
long term as recurrence rates can
range from 10 to 20 percent, even
with gross total resection.
This heterogeneous group of tumors arises from the
“support cells” of the brain, the glia. They account for
45 percent of CNS tumors in patients 20 to 34 years old.
Eighty percent of low-grade gliomas present with seizure.
Patients have a variable course ranging from two to 20
years before malignant degeneration of the tumor.
Surgery is first-line treatment with the goal being
maximal safe resection. Adjuvant radiation alone
improves seizure control and progression-free survival by
two years but does not affect overall survival. Radiation
followed by PCV chemotherapy significantly improves
overall survival by five years in higher-risk patients
(subtotal tumor resections or age > 40).
Favorable prognostic factors include oligodendroglia
pathology, age < 40, gross total resection of tumor,
IDH-1 mutation and 1p19q chromosomal deletions.
These tumors are classified as WHO grade III and grade
IV gliomas. The incidence is 5/100,000, and 14,000 new
cases are diagnosed annually. Seventy percent of these are
glioblastoma, the most common malignant brain tumor.
GBM is frequently diagnosed in the sixth decade.
Symptoms onset is typically short (<3 months).
Headache, seizure and neurological deficit are all
Left, an MRI scan showed a large acoustic neuroma in a
32-year-old woman with balance difficulties and hearing
loss. She underwent uncomplicated resection of the
lesion with full preservation of facial nerve function. A
postoperative MRI, right, showed no evidence of residual
tumor. The patient continues to do well clinically.
Surgical resection of at least 95 to 98 percent of
glioblastoma has been shown to improve prognosis.
Standard adjuvant therapy consists of concurrent
radiation and TMZ chemotherapy followed by
maintenance TMZ. Tumor treatment fields is a novel
FDA-approved technology where electric fields are used
to interfere with mitotic spindle formation and cancer
Overall prognosis for GBM is poor. Median survival
is 14.6 months. Positive prognostic factors are extent of
resection, age < 60, Karnofsky performance score > 70
and a cell proliferation index < 20 percent.
MGMT is a gene involved in DNA replication.
MGMT promoter methylation in GBM increases the
two-year survival rate to 46 percent versus 14 percent
without MGMT methylation.
Pituitary adenomas are quite common. Cadaver studies
indicate that over 10 percent of the population may
harbor small pituitary tumors. Many are incidentally
found. Symptomatic tumors present via mass effect on
the normal gland, the optic chasm, the cavernous sinus or
via hormonal effects. Pituitary apoplexy is a hemorrhagic
or ischemic infarction of the pituitary gland, which can
result in severe headache, visual loss and/or diplopia.
Presentation is typically acute and warrants referral to the
Hormone-secreting tumors are known as functional
tumors. These make up slightly less than 50 percent of
tumors and are predominantly of the prolactin, growth
hormone or ACTH-secreting variety. Many “nonfunctioning”
tumors actually produce FSH and LH but
are clinically silent.
Smaller, nonfunctional tumors can be followed.
Prolactinomas are treated first-line with dopamine agonist
therapy. Surgery is indicated for all other functional
tumors and larger tumors with suprasellar extension.
Metastatic brain tumors are actually the most common
brain neoplasm as a group. They outnumber primary brain
tumors by almost 3 to 1. Like gliomas, symptoms are
related to location. There is a predilection for the periphery
of the cerebrum, but any structure in the nervous system
or adjacent areas can be affected. Headache, seizure and
neurologic deficit are common presentations.
Lung cancer is the most common type of brain
metastasis. Breast cancer, melanoma, renal cancer and
colorectal cancer will also commonly metastasize to the
brain. Radiation therapy is the mainstay of treatment.
Surgery is indicated in certain patients with solitary
tumors or significant mass effect, or if tissue diagnosis is
necessary. Stereotactic radiosurgery may also be used in
lieu of whole-brain radiation in certain patients.