General Information About Adult Central Nervous System (CNS) Tumors
Incidence and Mortality
Brain tumors account for 85% to 90% of all primary central nervous system (CNS) tumors. Estimated new cases and deaths from brain tumors and other nervous system tumors in the United States in 2018:
- New cases: 23,880.
- Deaths: 16,830.
Available registry data from the Surveillance, Epidemiology, and End Results (SEER) database for 2011 indicate that the combined incidence of primary invasive CNS tumors in the United States is 6.4 per 100,000 persons per year, with an estimated mortality of 4.3 per 100,000 persons per year. Worldwide, approximately 256,213 new cases of brain and other CNS tumors were diagnosed in the year 2012, with an estimated 189,382 deaths.
In general, the incidence of primary CNS tumors is higher in whites than in blacks, and mortality is higher in males than in females.
Primary brain tumors include the following in decreasing order of frequency:
- Anaplastic astrocytomas and glioblastomas (38% of primary brain tumors).
- Meningiomas and other mesenchymal tumors (27% of primary brain tumors).
- Pituitary tumors.
- CNS lymphomas.
- Low-grade astrocytomas.
Primary spinal tumors include the following in decreasing order of frequency:
- Schwannomas, meningiomas, and ependymomas (79% of primary spinal tumors).
- Vascular tumors.
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.
Few definitive observations have been made about environmental or occupational causes of primary CNS tumors.
The following potential risk factors have been considered:
- Exposure to vinyl chloride may be a risk factor for glioma.
- Epstein-Barr virus infection has been implicated in the etiology of primary CNS lymphoma.
- Transplant recipients and patients with AIDS have a substantially increased risk of primary CNS lymphoma.[1,5] (Refer to the PDQ summary on Primary CNS Lymphoma Treatment for more information.)
The familial tumor syndromes and related chromosomal abnormalities that are associated with CNS neoplasms include the following:[6,7]
- 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).
- Nevoid basal cell carcinoma syndrome (9q22.3).
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 loss of appetite, nausea, and vomiting.
- Changes in personality, mood, mental capacity, and concentration.
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.
All brain tumors, whether primary, metastatic, malignant, or benign, must be differentiated from other space-occupying lesions that can have similar clinical presentations, such as abscesses, arteriovenous malformations, and infarctions.
Contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) have complementary roles in the diagnosis of CNS neoplasms.[1,9,10]
- The speed of CT is desirable for evaluating clinically unstable patients. CT is superior for detecting calcifications, skull lesions, and hyperacute hemorrhages (bleeding less than 24 hours old) and helps direct differential diagnosis and immediate management.
- MRI has superior soft-tissue resolution. MRI can better detect isodense lesions, tumor enhancements, and associated findings such as edema, all phases of hemorrhagic states (except hyperacute), and infarctions. 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. Cases in which the clinical and radiologic picture clearly point to a benign tumor, which could potentially be managed with active surveillance without biopsy or treatment, are the exception. For other cases, 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 almost all locations in the brain.
Several genetic alterations have emerged in recent years as powerful prognostic factors in diffuse glioma (astrocytoma, oligodendroglioma, mixed glioma, and glioblastoma), and these alterations may guide patient management. Specific alterations include the following:
- DNA methylation of the O6-methylguanine-DNA methyltransferase (MGMT) gene promoter.
- Mutation of isocitrate dehydrogenase (IDH) 1 (IDH1) or IDH2 genes.
- Codeletion of chromosomes 1p and 19q.
(Refer to the Treatment of Primary Central Nervous System Tumors by Tumor Type section of this summary for more information.)
Refer to the following PDQ summaries for more information:
- 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.
- American Cancer Society: Cancer Facts and Figures 2018. Atlanta, Ga: American Cancer Society, 2018. Available online. Last accessed August 3, 2018.
- Howlader N, Noone AM, Krapcho M, et al., eds.: SEER Cancer Statistics Review, 1975-2011. Bethesda, Md: Thailand Cancer Help, 2014. Also available online. Last accessed June 1, 2018.
- Ferlay J, Soerjomataram I, Ervik M, et al.: GLOBOCAN 2012 v1.0, Cancer Incidence and Mortality Worldwide. Lyon, France: International Agency for Research on Cancer, 2013. IARC CancerBase No. 11. Available online. Last accessed August 2, 2018.
- 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.
- Cloughesy T, Selch MT, Liau L: Brain. In: Haskell CM: Cancer Treatment. 5th ed. Philadelphia, Pa: WB Saunders Co, 2001, pp 1106-42.
- 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]
- Ricci PE: Imaging of adult brain tumors. Neuroimaging Clin N Am 9 (4): 651-69, 1999. [PUBMED Abstract]