General Information About Adult Brain Tumors
Incidence and Mortality
Estimated new cases and deaths from brain and other nervous system tumors in the United States in 2015:
- New cases: 22,850.
- Deaths: 15,320.
Brain tumors account for 85% to 90% of all primary central nervous system (CNS) tumors. Available registry data from the Surveillance, Epidemiology, and End Results (SEER) database for 2007 indicate that the combined incidence of primary invasive CNS tumors in the United States is 6.36 per 100,000 persons per year with an estimated mortality of 4.22 per 100,000 persons per year. Worldwide, approximately 238,000 new cases of brain and other CNS tumors were diagnosed in the year 2008, with an estimated 175,000 deaths. In general, the incidence of primary brain tumors is higher in whites than in blacks, and mortality is higher in males than in females.
Few definitive observations on environmental or occupational causes of primary CNS tumors have been made. Exposure to vinyl chloride may predispose to the development of glioma. Epstein-Barr virus infection has been implicated in the etiology of primary CNS lymphoma. Transplant recipients and patients with the acquired immunodeficiency syndrome have substantially increased risks for primary CNS lymphoma.[2,5] (Refer to the PDQ summary on Primary CNS Lymphoma Treatment for more information.)
The glial cell tumors, anaplastic astrocytoma and glioblastoma, account for approximately 38% of primary brain tumors. Since anaplastic astrocytomas represent less than 10% of all CNS gliomas, phase III randomized trials restricted to the anaplastic astrocytomas are not practical. Meningiomas and other mesenchymal tumors account for approximately 27% of primary brain tumors.
Other less-common primary brain tumors include the following in decreasing order of frequency:
- Pituitary tumors.
- CNS lymphomas.
- Low-grade astrocytomas.
Schwannomas, meningiomas, and ependymomas account for up to 79% of primary spinal tumors. 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]
The clinical presentation of various brain tumors is best appreciated by considering the relationship of signs and symptoms to anatomy. General signs and symptoms include the following:
- Visual changes.
- Gastrointestinal symptoms such as nausea, loss of appetite, and vomiting.
- 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. Other clinical presentations of brain tumors include focal cerebral syndromes such as seizures. 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. Among 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.
Computed tomography (CT) and magnetic resonance imaging (MRI) have complementary roles in the diagnosis of CNS neoplasms.[8,10] The speed of CT is desirable for evaluating clinically unstable patients. CT 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. MRI 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. In posttherapy imaging, single-photon emission computed tomography (SPECT) and positron emission tomography (PET) may be useful in differentiating tumor recurrence from radiation necrosis.
Biopsy confirmation to corroborate the suspected diagnosis of a primary brain tumor is critical, whether before surgery by needle biopsy or at the time of surgical resection, except in cases in which the clinical and radiologic picture clearly point to a benign tumor. Radiologic patterns may be misleading, and a definitive biopsy is needed to rule out other causes of space-occupying lesions, such as metastatic cancer or infection. CT- or MRI-guided stereotactic techniques can be used to place a needle safely and accurately into all but a very few inaccessible locations within the brain.
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 chemotherapy.[2,7,11-15] Other CNS tumors are associated with characteristic patterns of altered oncogenes, altered tumor-suppressor genes, and chromosomal abnormalities. 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. 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.[2,8] 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.[2,16]
Origins of metastatic brain tumors
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%).[2,16] Eighty percent of brain metastases occur in the cerebral hemispheres, 15% occur in the cerebellum, and 5% occur in the brain stem. Metastases to the brain are multiple in more than 70% of cases, but solitary metastases also occur. 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.
Primary Brain Tumors
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 the following:
- Patient history.
- Neurological examination.
- Diagnostic procedures, including a contrast MRI of the brain.
Patients may describe any of the following:
- Sensory defects.
- Gait problems.
Often, family members or friends may notice the following:
- Emotional lability.
- 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 primary tumor metastasis may be sufficient to make the diagnosis of brain metastasis. In the case of a solitary lesion or a questionable relationship to the primary tumor, a brain biopsy (via resection or stereotactic biopsy) may be necessary. 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.
Other PDQ summaries containing information related to adult and childhood brain cancer include the following:
- American Cancer Society: Cancer Facts and Figures 2015. Atlanta, Ga: American Cancer Society, 2015. Available online. Last accessed April 1, 2015.
- Mehta M, Vogelbaum MA, Chang S, et al.: Neoplasms of the central nervous system. In: DeVita VT Jr, Lawrence TS, Rosenberg SA: Cancer: Principles and Practice of Oncology. 9th ed. Philadelphia, Pa: Lippincott Williams & Wilkins, 2011, pp 1700-49.
- Altekruse SF, Kosary CL, Krapcho M, et al.: SEER Cancer Statistics Review, 1975-2007. Bethesda, Md: National Cancer Institute, 2010. Also available online. Last accessed April 1, 2015.
- Ferlay J, Shin HR, Bray F, et al.: GLOBOCAN 2008: Cancer Incidence and Mortality Worldwide in 2008. Lyon, France: IARC CancerBase No. 10. Available online. Last accessed April 24, 2015.
- Schabet M: Epidemiology of primary CNS lymphoma. J Neurooncol 43 (3): 199-201, 1999. [PUBMED Abstract]
- Behin A, Hoang-Xuan K, Carpentier AF, et al.: Primary brain tumours in adults. Lancet 361 (9354): 323-31, 2003. [PUBMED Abstract]
- Kleihues P, Cavenee WK, eds.: Pathology and Genetics of Tumours of the Nervous System. Lyon, France: International Agency for Research on Cancer, 2000.
- 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]
- Cloughesy T, Selch MT, Liau L: Brain. In: Haskell CM: Cancer Treatment. 5th ed. Philadelphia, Pa: WB Saunders Co, 2001, pp 1106-42.
- Ricci PE: Imaging of adult brain tumors. Neuroimaging Clin N Am 9 (4): 651-69, 1999. [PUBMED Abstract]
- Buckner JC: Factors influencing survival in high-grade gliomas. Semin Oncol 30 (6 Suppl 19): 10-4, 2003. [PUBMED Abstract]
- DeAngelis LM: Brain tumors. N Engl J Med 344 (2): 114-23, 2001. [PUBMED Abstract]
- 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]
- Giordana MT, Ghimenti C, Leonardo E, et al.: Molecular genetic study of a metastatic oligodendroglioma. J Neurooncol 66 (3): 265-71, 2004. [PUBMED Abstract]
- Hoang-Xuan K, Capelle L, Kujas M, et al.: Temozolomide as initial treatment for adults with low-grade oligodendrogliomas or oligoastrocytomas and correlation with chromosome 1p deletions. J Clin Oncol 22 (15): 3133-8, 2004. [PUBMED Abstract]
- Patchell RA: The management of brain metastases. Cancer Treat Rev 29 (6): 533-40, 2003. [PUBMED Abstract]
- Schaefer PW, Budzik RF Jr, Gonzalez RG: Imaging of cerebral metastases. Neurosurg Clin N Am 7 (3): 393-423, 1996. [PUBMED Abstract]