Brain tumor overview: Difference between revisions
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Imaging plays a central role in the diagnosis of brain tumors. On head CT scan, brain cancer is characterized by hypodense mass lesions. | Imaging plays a central role in the diagnosis of brain tumors. On head CT scan, brain cancer is characterized by hypodense mass lesions. | ||
===MRI=== | |||
Imaging plays a central role in the diagnosis of brain tumors. On MRI brain, brain tumor is characterized by hypointense or isointense on T1-weighted scans, or hyperintense on T2-weighted MRI. | |||
===Other Diagnostic Studies=== | ===Other Diagnostic Studies=== | ||
Revision as of 19:14, 21 August 2015
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Brain tumor Microchapters |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
A brain tumor is any intracranial tumor created by abnormal and uncontrolled cell division, normally either in the brain itself (neurons, glial cells (astrocytes, oligodendrocytes, ependymal cells), lymphatic tissue, blood vessels), in the cranial nerves (myelin-producing Schwann cells), in the brain envelopes (meninges), skull, pituitary and pineal gland, or spread from cancers primarily located in other organs (metastatic tumors). Primary (true) brain tumors are commonly located in the posterior cranial fossa in children and in the anterior two-thirds of the cerebral hemispheres in adults, although they can affect any part of the brain. In the United States in the year 2005, it was estimated that there were 43,800 new cases of brain tumors (Central Brain Tumor Registry of the United States, Primary Brain Tumors in the United States, Statistical Report, 2005 - 2006) [1], which accounted for 1.4 percent of all cancers, 2.4 percent of all cancer deaths[2], and 20–25 percent of pediatric cancers[2][3]. Ultimately, it is estimated that there are 13,000 deaths/year as a result of brain tumors[1].
Historical Perspective
Classification
Brain tumors can be classified into two main categories: primary and secondary tumors. Primary tumors originate in astrocytes, oligodendrocytes and ependymal cells. Secondary tumors originate in malignant cancers located primarily in other organs. Brain tumors are classified depending on location of the tumor, type of tissue involved and whether they are benign or malignant.
Pathophysiology
Causes
The cause of brain tumors is unknown.[4]
Differentiating brain tumors from other diseases
Brain tumors should be differentiated from essential tremor, stroke, chronic subdural hematoma, meningitis, orbital optic neuritis, arteriovenous malformation, intraocular optic neuritis and brain abscess.
Epidemiology and Demographics
In 2012, the prevalence and incidence of brain tumors were 148,818 and 6.4 per 100,000 persons per year respectively. The case-mortality rate of brain tumors is 4.4 per 100,000 persons per year. Patients of all age-group develop this cancer. Males are more affected with brain tumors than females. It usually affects individuals of the caucasian race. African Americans are less likely to develop this cancer.
Risk factors
Brain tumors are associated with a number of predisposing risk factors such as radiation, inherited conditions like neurofibromatosis; von Hippel-Lindau syndrome; Li-Fraumeni syndrome; Turcot syndrome, viruses such as Ebstein-Barr virus, chemicals such as formaldehyde; vinyl chloride; acrylnitrile and genetic factors.
Natural History, Complications and Prognosis
The complications of brain tumors are brain herniation, loss of brain function and recurrence. The prognosis in primary brain tumors depends on the type of tumor, age, functional status of the patient, the extent of surgical tumor removal, spread of metastasis and biogenetic markers.[5]. Patients with benign gliomas may survive for many years[6][7] while survival in most cases of glioblastoma multiforme is limited to a few months after diagnosis. The 5-year survival rate is 33.3%.
Diagnosis
Staging and Grading
The subtypes of brain tumors have different staging systems based on the grade, extent of spread, size and presence of distant metastases. The grades of brain tumors are subdivided into Grades 1,2,3 and 4. The lower the grade, better the prognosis.
History and Symptoms
The most common symptoms of brain tumors are headache, seizures, visual changes and changes in personality, mood and concentration.
Physical examination
Common physical examination findings of brain tumors include altered sense of consciousness, anisocoria, papilledema and focal neurological deficits.
CT
Imaging plays a central role in the diagnosis of brain tumors. On head CT scan, brain cancer is characterized by hypodense mass lesions.
MRI
Imaging plays a central role in the diagnosis of brain tumors. On MRI brain, brain tumor is characterized by hypointense or isointense on T1-weighted scans, or hyperintense on T2-weighted MRI.
Other Diagnostic Studies
Electrophysiological exams, such as electroencephalography (EEG) play a marginal role in the diagnosis of brain tumors. The definitive diagnosis of brain tumor can only be confirmed by histological examination of tumor tissue samples obtained either by means of brain biopsy or open surgery. The histologic examination is essential for determining the appropriate treatment and the correct prognosis.
Treatment
Medical Therapy
Although there is no generally accepted therapeutic management for primary brain tumors, a surgical attempt at tumor removal or at least cytoreduction (that is, removal of as much tumor as possible, in order to reduce the number of tumor cells available for proliferation) is considered in most cases[8]. However, due to the infiltrative nature of these lesions, tumor recurrence, even following an apparently complete surgical removal, is not uncommon. Postoperative radiotherapy and chemotherapy are integral parts of the therapeutic standard for malignant tumors. Radiotherapy may also be administered in cases of "low-grade" gliomas, when a significant tumor burden reduction could not be achieved surgically.
Surgery
Meningiomas, with the exception of some tumors located at the skull base, can be successfully removed surgically, but the chances are less than 50%. In more difficult cases, stereotactic radiosurgery, such as Gamma Knife radiosurgery, remains a viable option. Most pituitary adenomas can be removed surgically, often using a minimally invasive approach through the nasal cavity and skull base (trans-nasal, trans-sphenoidal approach). Large pituitary adenomas require a craniotomy (opening of the skull) for their removal. Radiotherapy, including stereotactic approaches, is reserved for the inoperable cases.
References
- ↑ 1.0 1.1 Greenlee RT, Murray T, Bolden S, Wingo PA. Cancer statistics, 2000. CA Cancer J Clin 2000;50:7-33. PDF. PMID 10735013.
- ↑ 2.0 2.1 American Cancer Society. Accessed June 2000.
- ↑ Chamberlain MC, Kormanik PA. Practical guidelines for the treatment of malignant gliomas. West J Med 1998;168:114-120. PMID 9499745.
- ↑ National Library of Medicine.http://www.nlm.nih.gov/medlineplus/cancer.html
- ↑ Nicolato A, Gerosa MA, Fina P, Iuzzolino P, Giorgiutti F, Bricolo A. Prognostic factors in low-grade supratentorial astrocytomas: a uni-multivariate statistical analysis in 76 surgically treated adult patients. Surg Neurol 1995;44:208-21; discussion 221-3. PMID 8545771.
- ↑ Janny P, Cure H, Mohr M, Heldt N, Kwiatkowski F, Lemaire JJ, Plagne R, Rozan R. Low grade supratentorial astrocytomas. Management and prognostic factors. Cancer 1994;73:1937-45. PMID 8137221.
- ↑ Piepmeier J, Christopher S, Spencer D, Byrne T, Kim J, Knisel JP, Lacy J, Tsukerman L, Makuch R. Variations in the natural history and survival of patients with supratentorial low-grade astrocytomas. Neurosurgery 1996;38:872-8; discussion 878-9. PMID 8727811.
- ↑ Nakamura M, Konishi N, Tsunoda S, Nakase H, Tsuzuki T, Aoki H, Sakitani H, Inui T, Sakaki T. Analysis of prognostic and survival factors related to treatment of low-grade astrocytomas in adults. Oncology 2000;58:108-16. PMID 10705237.