Note: Information on brain tumors in children is available in the PDQ summary on Childhood Brain and Spinal Cord Tumors Treatment Overview.

Note: Estimated new cases and deaths from brain and other nervous system tumors in the United States in 2008:[1]

• New cases: 21,810.
• Deaths: 13,070.

Brain tumors account for 85% to 90% of all primary central nervous system (CNS) tumors.[2] Available registry data from the Surveillance, Epidemiology, and End Results (SEER) database for 1996 to 2000 indicate that the combined incidence of primary invasive CNS tumors in the United States is 6.6 per 100,000 persons per year with an estimated mortality of 4.7 per 100,000 persons per year.[3] Worldwide, approximately 176,000 new cases of brain and other CNS tumors were diagnosed in the year 2000, with an estimated mortality of 128,000.[4] In general, the incidence of primary brain tumors is higher in whites than in blacks, and mortality is higher in males than in females.[2]

Anaplastic astrocytoma and glioblastoma account for approximately 38% of primary brain tumors; meningiomas and other mesenchymal tumors account for approximately 27%.[2] Other less common primary brain tumors include pituitary tumors, schwannomas, CNS lymphomas, oligodendrogliomas, ependymomas, low-grade astrocytomas, and medulloblastomas, in decreasing order of frequency. Schwannomas, meningiomas, and ependymomas account for as much as 79% of primary spinal tumors.[5] Other less common primary spinal tumors include sarcomas, astrocytomas, vascular tumors, and chordomas, in decreasing order of frequency. The familial tumor syndromes (and respective chromosomal abnormalities that are associated with CNS neoplasms) include neurofibromatosis type I (17q11), neurofibromatosis type II (22q12), von Hippel-Lindau disease (3p25-26), tuberous sclerosis (9q34, 16p13), Li-Fraumeni syndrome (17p13), Turcot syndrome type 1 (3p21, 7p22), Turcot syndrome type 2 (5q21), and nevoid basal cell carcinoma syndrome (9q22.3).[6,7]

Few definitive observations on environmental or occupational causes of primary CNS tumors have been made.[2] Exposure to vinyl chloride may predispose to the development of glioma.[8] Epstein-Barr virus infection has been implicated in the etiology of primary CNS lymphoma.[9] Transplant recipients and patients with the acquired immunodeficiency syndrome have substantially increased risks for primary CNS lymphoma.[2,10] (Refer to the PDQ summary on Primary CNS Lymphoma Treatment for more information.)

The clinical presentation of various brain tumors is best appreciated by considering the relationship of signs and symptoms to anatomy.[2] General signs and symptoms include headaches; gastrointestinal symptoms such as nausea, loss of appetite, and vomiting; and changes in personality, mood, mental capacity, and concentration. Whether primary, metastatic, malignant, or benign, brain tumors must be differentiated from other space-occupying lesions such as abscesses, arteriovenous malformations, and infarction, which can have a similar clinical presentation.[11] Other clinical presentations of brain tumors include focal cerebral syndromes such as seizures.[2] Seizures are a presenting symptom in approximately 20% of patients with supratentorial brain tumors and may antedate the clinical diagnosis by months to years in patients with slow-growing tumors. Of all patients with brain tumors, 70% with primary parenchymal tumors and 40% with metastatic brain tumors develop seizures at some time during the clinical course.[12]

Computed tomography (CT) and magnetic resonance imaging (MRI) have complementary roles in the diagnosis of CNS neoplasms.[11,13] The speed of CT is desirable for evaluating clinically unstable patients; it is superior for detecting calcification, skull lesions, and hyperacute hemorrhage (bleeding less than 24 hours old) and helps direct differential diagnosis as well as immediate management. MRI has superior soft-tissue resolution; it can better detect isodense lesions, tumor enhancement, and associated findings such as edema, all phases of hemorrhagic states (except hyperacute), and infarction. High-quality MRI is the diagnostic study of choice in the evaluation of intramedullary and extramedullary spinal cord lesions.[2] In posttherapy imaging, single-photon emission computed tomography (SPECT) and positron emission tomography (PET) may be useful in differentiating tumor recurrence from radiation necrosis.[11]

Specific genetic or chromosomal abnormalities involving deletions of 1p and 19q have been identified for a subset of oligodendroglial tumors, which have a high response rate to lomustine, procarbazine, and vincristine (PCV) therapy.[7,14-18] Other CNS tumors are associated with characteristic patterns of altered oncogenes, altered tumor-suppressor genes, and chromosomal abnormalities. As noted above, familial tumor syndromes with defined chromosomal abnormalities are associated with gliomas. (Refer to the Classification section of this summary for more information.)

Metastatic Brain Tumors

Brain metastases outnumber primary neoplasms by at least 10 to 1, and they occur in 20% to 40% of cancer patients.[19] Because no national cancer registry documents brain metastases, the exact incidence is unknown, but it has been estimated that 98,000 to 170,000 new cases are diagnosed in the United States each year.[2,11] This number may be increasing because of the capacity of MRI to detect small metastases and because of prolonged survival resulting from improved systemic therapy.[2,19]

The most common primary cancers metastasizing to the brain are lung cancer (50%), breast cancer (15%–20%), unknown primary cancer (10%–15%), melanoma (10%), and colon cancer (5%).[19,20] Eighty percent of brain metastases occur in the cerebral hemispheres, 15% occur in the cerebellum, and 5% occur in the brain stem.[20] Metastases to the brain are multiple in more than 70% of cases, but solitary metastases also occur.[19] Brain involvement can occur with cancers of the nasopharyngeal region by direct extension along the cranial nerves or through the foramina at the base of the skull. Dural metastases may constitute as much as 9% of total CNS metastases.[21]

A lesion in the brain should not be assumed to be a metastasis just because a patient has had a previous cancer; such an assumption could result in overlooking appropriate treatment of a curable tumor. Primary brain tumors rarely spread to other areas of the body, but they can spread to other parts of the brain and to the spinal axis.

The diagnosis of brain metastases in cancer patients is based on patient history, neurological examination, and diagnostic procedures. Patients may describe headaches, weakness, seizures, sensory defects, or gait problems. Often, family members or friends may notice lethargy, emotional liability, or personality change.

A physical examination may show objective neurological findings or only minor cognitive changes. The presence of multiple lesions and a high predilection of tumor may be sufficient to make the diagnosis of metastases. In the case of a solitary lesion or a questionable relationship to the primary tumor, a brain biopsy (usually a stereotactic biopsy) may be necessary. In one study, the diagnosis of single brain metastasis was changed in 6 of 54 patients after the lesion was biopsied. The six patients had primary brain tumors or infectious and inflammatory lesions.[22] CT scans with contrast or MRIs with gadolinium are quite sensitive in diagnosing the presence of metastases. PET scanning and spectroscopic evaluation are new strategies to diagnose cerebral metastases and to differentiate the metastases from other intracranial lesions.[23]

References

1. American Cancer Society.: Cancer Facts and Figures 2008. Atlanta, Ga: American Cancer Society, 2008. Also available online. Last accessed October 1, 2008. 
   
   
2. Levin VA, Leibel SA, Gutin PH: Neoplasms of the central nervous system. In: DeVita VT Jr, Hellman S, Rosenberg SA, eds.: Cancer: Principles and Practice of Oncology. 6th ed. Philadelphia, Pa: Lippincott Williams & Wilkins, 2001, pp 2100-60. 
   
   
3. Trends in SEER incidence and U.S. mortality using the joinpoint regression program 1975-2000 with up to three joinpoints by race and sex. In: Ries LAG, Eisner MP, Kosary CL, et al.: SEER Cancer Statistics Review, 1975-2000. Bethesda, Md: National Cancer Institute, 2003., Section 3: Brain and Other Nervous System Cancer (Invasive), Table III-1. Also available online. Last accessed August 4, 2008. 
   
   
4. Parkin DM, Bray F, Ferlay J, et al.: Estimating the world cancer burden: Globocan 2000. Int J Cancer 94 (2): 153-6, 2001.  [PUBMED Abstract]
   
   
5. Preston-Martin S: Descriptive epidemiology of primary tumors of the spinal cord and spinal meninges in Los Angeles County, 1972-1985. Neuroepidemiology 9 (2): 106-11, 1990.  [PUBMED Abstract]
   
   
6. Behin A, Hoang-Xuan K, Carpentier AF, et al.: Primary brain tumours in adults. Lancet 361 (9354): 323-31, 2003.  [PUBMED Abstract]
   
   
7. Kleihues P, Cavenee WK, eds.: Pathology and Genetics of Tumours of the Nervous System. Lyon, France: International Agency for Research on Cancer, 2000. 
   
   
8. Moss AR: Occupational exposure and brain tumors. J Toxicol Environ Health 16 (5): 703-11, 1985.  [PUBMED Abstract]
   
   
9. Hochberg FH, Miller G, Schooley RT, et al.: Central-nervous-system lymphoma related to Epstein-Barr virus. N Engl J Med 309 (13): 745-8, 1983.  [PUBMED Abstract]
   
   
10. Schabet M: Epidemiology of primary CNS lymphoma. J Neurooncol 43 (3): 199-201, 1999.  [PUBMED Abstract]
    
    
11. Hutter A, Schwetye KE, Bierhals AJ, et al.: Brain neoplasms: epidemiology, diagnosis, and prospects for cost-effective imaging. Neuroimaging Clin N Am 13 (2): 237-50, x-xi, 2003.  [PUBMED Abstract]
    
    
12. Cloughesy T, Selch MT, Liau L: Brain. In: Haskell CM: Cancer Treatment. 5th ed. Philadelphia, Pa: WB Saunders Co, 2001, pp 1106-42. 
    
    
13. Ricci PE: Imaging of adult brain tumors. Neuroimaging Clin N Am 9 (4): 651-69, 1999.  [PUBMED Abstract]
    
    
14. Buckner JC: Factors influencing survival in high-grade gliomas. Semin Oncol 30 (6 Suppl 19): 10-4, 2003.  [PUBMED Abstract]
    
    
15. Louis DN, Cavenee WK: Neoplasms of the central nervous system. In: DeVita VT Jr, Hellman S, Rosenberg SA, eds.: Cancer: Principles and Practice of Oncology. 6th ed. Philadelphia, Pa: Lippincott Williams & Wilkins, 2001, pp 2091-100. 
    
    
16. DeAngelis LM: Brain tumors. N Engl J Med 344 (2): 114-23, 2001.  [PUBMED Abstract]
    
    
17. Ueki K, Nishikawa R, Nakazato Y, et al.: Correlation of histology and molecular genetic analysis of 1p, 19q, 10q, TP53, EGFR, CDK4, and CDKN2A in 91 astrocytic and oligodendroglial tumors. Clin Cancer Res 8 (1): 196-201, 2002.  [PUBMED Abstract]
    
    
18. Giordana MT, Ghimenti C, Leonardo E, et al.: Molecular genetic study of a metastatic oligodendroglioma. J Neurooncol 66 (3): 265-71, 2004.  [PUBMED Abstract]
    
    
19. Patchell RA: The management of brain metastases. Cancer Treat Rev 29 (6): 533-40, 2003.  [PUBMED Abstract]
    
    
20. Wen PY, Black PM, Loeffler JS: Treatment of metastatic cancer. In: DeVita VT Jr, Hellman S, Rosenberg SA, eds.: Cancer: Principles and Practice of Oncology. 6th ed. Philadelphia, Pa: Lippincott Williams & Wilkins, 2001, pp 2655-70. 
    
    
21. Posner JB, Chernik NL: Intracranial metastases from systemic cancer. Adv Neurol 19: 579-92, 1978.  [PUBMED Abstract]
    
    
22. Noordijk EM, Vecht CJ, Haaxma-Reiche H, et al.: The choice of treatment of single brain metastasis should be based on extracranial tumor activity and age. Int J Radiat Oncol Biol Phys 29 (4): 711-7, 1994.  [PUBMED Abstract]
    
    
23. Schaefer PW, Budzik RF Jr, Gonzalez RG: Imaging of cerebral metastases. Neurosurg Clin N Am 7 (3): 393-423, 1996.  [PUBMED Abstract]
    
    

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