Definition
A.Brain tumors most commonly arise from distant metastasis of other primary malignancies.
B.Subtypes and classification: Primary brain tumors are classified according to the histologic pattern of cell differentiation.
1.Gliomas.
a.Most commonly occurring primary brain tumors.
b.Several types, including:
i.Glioblastomas (most common).
ii.Astrocytomas.
iii.Oligodendrogliomas.
iv.Ependymomas.
2.Meningiomas.
3.Nerve sheath tumors.
4.Pituitary tumors.
5.Primary central nervous system (CNS) lymphoma (associated with HIV/AIDS and immunosuppression).
Incidence
A.The U.S. incidence rate of primary brain and CNS tumors in patients 20 years of age and older is 28.6 per 100,000 persons.
B.The incidence rate for children (ages 0–19) is much lower, 5.6 per 100,000 persons.
C.The 5-year overall survival rate for all malignant brain tumors is ∼34%.
D.Survival rates depend on histologic subtype. For example, the 5-year overall survival rates for anaplastic astrocytoma and glioblastoma are 28% and 5%, respectively.
Pathogenesis
A.Primary brain tumors proliferate from brain tissue most commonly from glial tissue.
1.Tumors that arise from glial tissue include astrocytomas, oligodendrogliomas, and ependymomas.
2.Nonglial primary type brain tumors are meningiomas, schwannomas, craniopharyngiomas, germ cell tumors, and pineal region tumors.
B.Typically primary brain tumors do not metastasize, although they can.
C.Secondary or metastatic brain tumors originate from another part of the body and spread to the brain.
1.Several types of secondary brain tumors spread quickly to the brain, including lung, breast, melanoma, colon, and kidney cancer.
Predisposing Factors
A.Ionizing radiation.
B.Exposure to cured foods.
C.HIV/AIDS.
D.Immunosuppression.
E.Cytomegalovirus (CMV) infection.
F.Familial predisposition.
1.Neurofibromatosis type 1 (NF1) and type 2 (NF2).
2.Li–Fraumeni syndrome.
3.Turcot syndrome.
Subjective Data
A.Common complaints/symptoms.
1.Patients with low-grade tumors may initially be asymptomatic.
2.Symptoms are related to compression of intracranial structures and/or increased intracranial pressure (ICP).
3.Nausea and/or vomiting may occur due to increased ICP.
4.Neurological symptoms.
a.Seizures.
b.Headaches.
c.Focal neurological deficits.
d.Syncope.
e.Visual changes.
f.Gait instability.
5.Symptoms/signs associated with pituitary tumors (e.g., prolactinomas).
a.Bitemporal hemianopsia due to compression of the optic chiasm.
b.Spontaneous bilateral nipple discharge.
c.Hypogonadism.
Physical Examination
A.Assess for evidence of primary tumors (most commonly lung followed by melanoma, renal cell, breast, and colorectal).
B.A full neurological exam must be performed in all patients with suspected brain tumors.
1.Mini-Mental State Exam.
2.Motor strength in all extremities.
3.Sensory testing.
4.Visual field testing.
5.Reflexes.
6.Cranial nerve testing.
7.Gait and cerebellar assessment.
8.Rectal tone.
Diagnostic Tests
A.Contrast enhanced MRI (diagnostic standard).
B.Single photon emission CT (SPECT) imaging may be used to detect defects in the blood-brain barrier and may be considered to distinguish benign from malignant brain lesions.
C.Consider lumbar puncture (contraindicated if evidence of elevated intracranial pressure).
D.Hormone evaluation for pituitary tumors.
E.Consider metastatic disease.
1.If metastatic disease is suspected, search for primary tumor (most commonly lung primary).
2.Biopsy of brain lesion is not necessary if metastatic disease is confirmed.
Differential Diagnosis
A.Gliomas.
B.Meningiomas.
C.Nerve sheath tumors.
D.Pituitary tumors.
E.Primary CNS lymphomas.
Evaluation and Management Plan
A.General plan.
1.Management of brain tumors is dependent on definitive pathology for diagnosis.
2.Biopsy or total resection (if possible) is recommended for all suspected brain malignancy.
3.The blood–brain barrier limits CNS penetration of many chemotherapies.
4.Treatment approach varies depending on grade.
a.Low-grade glioma (grade I or II).
i.Maximal safe resection is recommended for all patients.
ii.Low-risk patients.
1)Observation postoperatively is reasonable due to slow growth.
2)MRI should be obtained every 3 to 6 months for the first 5 years, then annually.
iii.High-risk patients.
1)Age greater than 40, subtotal resection, or unfavorable molecular features.
2)Consider radiation and adjuvant chemo-therapy.
b.High-grade glioma (grade III or IV).
i.Maximal safe resection.
ii.Combination therapy with adjuvant radiation therapy and chemotherapy following resection.
iii.Chemotherapy.
iv.Targeted therapy.
5.Seizure prophylaxis.
a.Patients with no prior history of seizures generally do not require prophylactic anticonvulsants.
b.Patients undergoing surgical resection of supratentorial tumors should be placed on prophylactic anticonvulsants.
B.Acute care issues in brain/CNS cancers.
1.Seizures.
2.Cerebral edema.
Follow-Up
A.Follow-up with the team on a regular basis is important, including medical oncology, radiation oncology, and the neurosurgeon.
Consultation/Referral
A.Referral to a neurosurgeon for biopsy/resection.
1.Histologic review of the biopsy is the most crucial component of diagnosing brain tumors.
2.Histologic classification dictates therapeutic approach.
3.Pathologic review.
Special/Geriatric Considerations
A.Prognosis of the patient is highly dependent on tumor location, the ability to resect it, tumor type, and age of patient.
B.Patients may develop seizures related to the location or aggressiveness of the tumor.
Bibliography
Ostrom, Q. T., Gittleman, H., Fulop, J., Liu, M., Blanda, R., Kromer, C., … Barnholtz-Sloan, J. S. (2015). CBTRUS Statistical Report: Primary brain and central nervous system tumors diagnosed in the United States in 2008–2012. Neuro Oncology, 17(Suppl. 4), iv1–iv62.