Adult brain tumors overview
|
Adult brain tumors Microchapters |
|
Diagnosis |
|---|
|
Treatment |
|
Case Studies |
|
Adult brain tumors overview On the Web |
|
American Roentgen Ray Society Images of Adult brain tumors overview |
|
Risk calculators and risk factors for Adult brain tumors overview |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Anaplastic astrocytoma and glioblastoma account for approximately 38% of primary brain tumors; meningiomas and other mesenchymal tumors account for approximately 27%. 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. 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).
Causes
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.
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. 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.)
Epidemiology and Demographics
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 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. 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. In general, the incidence of primary brain tumors is higher in whites than in blacks, and mortality is higher in males than in females.
History and Symptoms
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 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. 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. 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.
Diagnosis
Computed tomography (CT) and magnetic resonance imaging (MRI) have complementary roles in the diagnosis of CNS neoplasms. 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. In posttherapy imaging, single-photon emission computed tomography (SPECT) and positron emission tomography (PET) may be useful in differentiating tumor recurrence from radiation necrosis.