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{{Use dmy dates|date=October 2012}}
{{Infobox medical condition
| Name = Brain tumor
| Image = Hirnmetastase MRT-T1 KM.jpg
| Caption = Brain [[metastasis]] in the right [[cerebral hemisphere]] from [[lung cancer]] shown on [[magnetic resonance imaging]].
| Field = [[Neurosurgery]], [[oncology]]
| ICD10 = {{ICD10|D|71}}, {{ICD10|D|33}},
| ICD9 = {{ICD9|191}}, {{ICD9|225.0}}
| ICDO =
| OMIM =
|DiseasesDB=30781
| MedlinePlus = 007222
| MedlinePlus_mult = {{MedlinePlus2|000768}}
| eMedicineSubj = emerg
| eMedicineTopic = 334
| MeshID = D001932
}}
A '''brain tumor''' or '''intracranial neoplasm''' occurs when abnormal cells form within the [[Human brain|brain]].<ref name=PDQ2014Pt>{{cite web|title=General Information About Adult Brain Tumors|url=http://www.cancer.gov/cancertopics/pdq/treatment/adultbrain/Patient/page1/AllPages|website=NCI|accessdate=8 June 2014|date=2014-04-14}}</ref> There are two main types of tumors: malignant or [[cancer]]ous tumors and [[benign tumor|benign]] tumors.<ref name=PDQ2014Pt/> Cancerous tumors can be divided
that have spread from somewhere else, known as [[brain metastasis]] tumors.<ref name=PDQ2014MD/> All types of brain tumors may produce symptoms that vary depending on the part of the brain involved.<ref name=PDQ2014Pt/> These may include [[headaches]], [[seizures]], problem with [[visual perception|vision]], [[vomiting]], and [[cognition|mental]] changes.<ref name=PDQ2014MD>{{cite web|title=Adult Brain Tumors Treatment
|url=http://www.cancer.gov/cancertopics/pdq/treatment/adultbrain/HealthProfessional/page1/AllPages|website=NCI|accessdate=8 June 2014|date=2014-02-28}}</ref><ref>{{cite book |last1=Longo |first1=Dan L |title=Harrison's principles of internal medicine |year=2012 |publisher=McGraw-Hill |isbn=978-0-07-174887-2 |page=3258 |edition=18th|chapter=369 Seizures and Epilepsy}}</ref> The headache is classically worse in the morning and goes away with vomiting.<ref name=PDQ2014Pt/> More specific problems may include difficulty in walking, speaking, and with sensation.<ref name=PDQ2014MD/><ref name=WCR2014CNS/> As the disease progresses [[unconsciousness]] may occur.<ref name=WCR2014CNS/>

<!-- Cause and Diagnosis -->
The cause of most brain tumors is unknown.<ref name=PDQ2014Pt/> [[Risk factor]]s that may occasionally be involved include a number of inherited conditions known as [[neurofibromatosis]] as well as exposure to the industrial chemical [[vinyl chloride]], the [[Epstein-Barr virus]], and [[ionizing radiation]].<ref name=PDQ2014Pt/><ref name=PDQ2014MD/><ref name=WCR2014CNS/> While concern has been raised about [[mobile phone]] use, the evidence is not clear.<ref name=WCR2014CNS/> The most common types of primary tumors in adults are: [[meningioma]]s (usually benign), and [[astrocytoma]]s such as [[glioblastoma]]s.<ref name=PDQ2014MD/> In children, the most common type is a malignant [[medulloblastoma]].<ref name=WCR2014CNS/> Diagnosis is usually by [[medical examination]] along with [[computed tomography]] or [[magnetic resonance imaging]].<ref name=PDQ2014Pt/> This is then often confirmed by a [[biopsy]].<ref name=PDQ2014MD/> Based on the findings, the tumors are divided into [[Grading of the tumors of the central nervous system|different grades of severity]].<ref name=PDQ2014MD/>

<!-- Treatment and Prognosis -->
Treatment may include some combination of [[surgery]], [[radiation therapy]] and [[chemotherapy]].<ref name=PDQ2014MD/> [[Anticonvulsant]] medication may be needed if seizures occur.<ref name=PDQ2014MD/> [[Dexamethasone]] and [[furosemide]] may be used to decrease swelling around the tumor.<ref name=PDQ2014MD/> Some tumors grow gradually, requiring only monitoring and possibly needing no further intervention.<ref name=PDQ2014MD/> Treatments that use a person's [[immune system]] are being studied.<ref name=PDQ2014Pt/> Outcome varies considerably depending on the type of tumor and how far it has spread at diagnosis.<ref name=WCR2014CNS/> Glioblastomas usually have poor outcomes while meningiomas usually have good outcomes.<ref name=WCR2014CNS/> The average [[five year survival rates|five-year survival rate]] for brain cancer in the United States is 33%.<ref>{{cite web|title=SEER Stat Fact Sheets: Brain and Other Nervous System Cance|url=http://seer.cancer.gov/statfacts/html/brain.html|website=NCI|accessdate=18 June 2014}}</ref>

<!-- Epidemiology -->
Secondary or [[metastasis|metastatic]] brain tumors are more common than primary brain tumors,<ref name=PDQ2014Pt/> with about half of metastases coming from [[lung cancer]].<ref name=PDQ2014Pt/> Primary brain tumors occur in around 250,000 people a year globally, making up less than 2% of cancers.<ref name=WCR2014CNS>{{cite book|title=World Cancer Report 2014.|date=2014|publisher=World Health Organization|isbn=9283204298|pages=Chapter 5.16}}</ref> In children younger than 15, brain tumors are second only to [[acute lymphoblastic leukemia]] as a cause of cancer.<ref name=WCR2014Peads>{{cite book|title=World Cancer Report 2014.|date=2014|publisher=World Health Organization|isbn=9283204298|pages=Chapter 1.3}}</ref> In Australia the average economic cost of a case of brain cancer is $1.9 million, the greatest of any type of cancer.<ref>{{cite web|title=Brain Tumour Facts 2011|url=http://www.btaa.org.au/BrainTumourFactSheet2011.pdf|website=Brain Tumour Alliance Australia|accessdate=9 June 2014|archiveurl=http://paperzz.com/doc/286239/pdf-file---brain-tumour-alliance-australia|archivedate=20 Nov 2014}}</ref>
{{TOC limit|3}}

==Signs and symptoms==
[[File:Brain headBorder.jpg|thumb|The main areas of the brain and limbic system.]]
The signs and symptoms of brain tumors are broad. People with brain tumors will experience them no matter if the tumor is benign (not cancerous) or cancerous.<ref>{{Cite web|url=http://www.merckmanuals.com/home/brain,-spinal-cord,-and-nerve-disorders/tumors-of-the-nervous-system/brain-tumors|title=Brain Tumors|access-date=2016-08-02}}</ref> Primary and secondary brain tumors present with similar symptoms, with symptoms depend on the location, size, and rate of growth of the tumor.<ref name="abta.org">{{Cite web|url=http://www.abta.org/brain-tumor-information/symptoms/mood-swings.html|title=Mood Swings and Cognitive Changes {{!}} American Brain Tumor Association|website=www.abta.org|access-date=2016-08-03}}</ref> For example, larger tumors in the frontal lobe can cause changes in the ability to think. However, a smaller tumor in an area such as [[Wernicke's area]] (small area responsible for language comprehension) can result in a greater loss of function.<ref>{{Cite web|url=http://www.brainsciencefoundation.org/bUnderstandbPrimaryBrainTumors/AdditionalResources/CopingWithPersonalityBehavioralChanges/tabid/283/Default.aspx|title=Coping With Personality & Behavioral Changes|website=www.brainsciencefoundation.org|access-date=2016-08-03}}</ref>

[[Intracranial pressure]] is usually the first sign of a brain tumor and it can cause persistent headaches.<ref name=":4">{{Cite web|url=http://www.abta.org/brain-tumor-information/symptoms/headaches.html?referrer=http://www.abta.org/brain-tumor-information/symptoms/mood-swings.html?referrer=https://www.google.com/|title=Headaches {{!}} American Brain Tumor Association|website=www.abta.org|access-date=2016-08-03}}</ref><ref name=":52">{{Cite web|url=http://milesforhope.org/index.php/facts/brain-tumor-symptoms|title=Brain Tumor Symptoms {{!}} Miles for Hope {{!}} Brain Tumor Foundation|last=Jones|first=Caleb|website=milesforhope.org|access-date=2016-08-03}}</ref> These headaches may not respond to headache remedies and they may be accompanied by vomiting.<ref name=":4" />

The brain is divided into 4 lobes and each lobe or area has its own function.<ref name=":02">{{Cite journal|last=Gregg|first=N.|date=2014|title="Neurobehavioural Changes In Patients Following Brain Tumour: Patients And Relatives Perspective."|url=|journal=Supportive Care In Cancer|volume=|issue=|doi=|pmid=|access-date=|via=}}</ref><ref name=":1">{{Cite web|url=http://www.brainsciencefoundation.org/bUnderstandbPrimaryBrainTumors/AdditionalResources/CopingWithPersonalityBehavioralChanges/tabid/283/Default.aspx|title=Coping With Personality & Behavioral Changes|website=www.brainsciencefoundation.org|access-date=2016-07-27}}</ref> A tumor in any of these lobes may affect the area's performance. The location of the tumor is often linked to the symptoms experienced but each person may experience something different.<ref name=":22">{{Cite web|url=http://www.abta.org/brain-tumor-information/symptoms/mood-swings.html?referrer=https://www.google.com/|title=Mood Swings and Cognitive Changes {{!}} American Brain Tumor Association|website=www.abta.org|access-date=2016-07-27}}</ref>

[[Frontal lobe]] tumors may contribute to poor reasoning, inappropriate social behavior, personality changes, poor planning, lower inhibition,<ref name=":22"/> and decreased production of speech ([[Broca's area]])

[[Temporal lobe]]: Tumors in this lobe may contribute to poor memory, loss of hearing,<ref name=":1" /> difficulty in language comprehension ([[Wernicke's area|Wernicke's area)]]

[[Parietal lobe]]: Tumors here may result in poor interpretation of languages, decreased sense of touch and pain, and poor spatial and visual perception<ref name=":3">{{Cite web|url=https://www.mayfieldclinic.com/PDF/PE-AnatBrain.pdf|title=Anatomy of the Brain|last=|first=|date=|website=|publisher=|access-date=}}</ref>

[[Occipital lobe]]: Damage to this lobe may result in poor or loss of vision<ref name=":3" />

[[Cerebellum]]: Tumors in this area may cause poor balance, muscle movement, and posture<ref name=":3" />

[[Brainstem|Brain stem]]: Tumors on this can affect blood pressure, swallowing, and heartbeat<ref name=":1" />

===Behavior changes===

Despite being a common symptom of brain tumors, little research is done on personality and behavior changes in patients with brain tumors.<ref name=":02"/> A person's personality may be altered due to the tumor damaging lobes of the brain. Since the frontal, temporal, and parietal lobes<ref name="abta.org"/> control inhibition, emotions, mood, judgement, reasoning, and behavior, a primary or secondary tumor in that region can cause inappropriate social behavior,<ref name=":52"/> temper tantrums,<ref name=":52"/> laughing at things that aren't funny,<ref name=":52"/> and even psychological symptoms such as depression and anxiety.<ref name=":22"/>

Personality changes can have damaging effects as they can result in unemployment, unstable relationships, and lack of control.<ref name=":02" />

==Cause==
Epidemiological studies are required to determine risk factors.<ref>{{cite journal|last1=Krishnatreya|first1=M|last2=Kataki|first2=AC|last3=Sharma|first3=JD|last4=Bhattacharyya|first4=M|last5=Nandy|first5=P|last6=Hazarika|first6=M|title=Brief descriptive epidemiology of primary malignant brain tumors from North-East India.|journal=Asian Pacific Journal of Cancer Prevention |date=2014|volume=15|issue=22|pages=9871–3|pmid=25520120|doi=10.7314/apjcp.2014.15.22.9871}}</ref> Aside from exposure to [[vinyl chloride]] or [[ionizing radiation]], there are no known environmental factors associated with brain tumors. Mutations and deletions of so-called [[tumor suppressor gene]]s, such as [[P53]], are thought to be the cause of some forms of brain tumor.<ref>{{cite book |vauthors=Kleihues P, Ohgaki H, Eibl RH, Reichel MB, Mariani L, Gehring M, Petersen I, Höll T, von Deimling A, Wiestler OD, Schwab M | chapter = Type and frequency of p53 mutations in tumors of the nervous system and its coverings | title = Molecular Neuro-oncology and Its Impact on the Clinical Management of Brain Tumors | pages = 25–31 | year = 1994 | publisher = Springer |isbn=3540573518 |series=Recent results in cancer research |volume=135}}</ref> Inherited conditions, such as [[Von Hippel–Lindau disease]], [[multiple endocrine neoplasia]], and [[Neurofibromatosis|neurofibromatosis type 2]] carry a high risk for the development of brain tumors.

Although studies have not shown any link between [[Mobile phone radiation and health|cell phone or mobile phone radiation]] and the occurrence of brain tumors,<ref>{{cite journal |vauthors=Frei P, Poulsen AH, Johansen C, Olsen JH, Steding-Jessen M, Schüz J | title = Use of mobile phones and risk of brain tumours: update of Danish cohort study. | journal = BMJ | volume = 343 | pages = d6387 | date = 19 October 2011 | pmid = 22016439 | pmc = 3197791 | doi = 10.1136/bmj.d6387 }}</ref> the [[World Health Organization]] has classified mobile phone radiation on the [[International Agency for Research on Cancer|IARC]] scale into [[List of IARC Group 2B carcinogens|Group 2B]] – possibly carcinogenic.<ref name="WHO_IARC_110531">{{cite press release|url= http://www.iarc.fr/en/media-centre/pr/2011/pdfs/pr208_E.pdf |format= PDF|title= IARC classifies radiofrequency electromagnetic fields as possibly carcinogenic to humans|work= [[World Health Organization]] press release N° 208|publisher= [[International Agency for Research on Cancer]]|date= 31 May 2011|accessdate= 2 June 2011}}</ref> Discounting claims that current cell phone usage may cause brain cancer, modern, third-generation (3G) phones emit, on average, about 1% of the energy emitted by the GSM (2G) phones that were in use when epidemiological studies that observed a slight increase in the risk for glioma – a malignant type of brain cancer –among heavy users of wireless and cordless telephones were conducted. <ref name=WCR2014CNS/>

==Pathophysiology==
[[File:Brain Cancer Regions.png|thumb|Brain cancer regions.]]

===Meninges===
Human brains are surrounded by a system of [[connective tissue]] membranes called [[meninges]] that separate the [[Human brain|brain]] from the [[Human skull|skull]]. This three-layered covering is composed of (from the outside in) the [[dura mater]] ("hard mother"), [[arachnoid mater]] ("spidery mother"), and [[pia mater]] ("tender mother"). The arachnoid and pia are physically connected and thus often considered as a single layer, the pia-arachnoid. Between the arachnoid mater and the pia mater is the [[subarachnoid space]] which contains [[cerebrospinal fluid]] (CSF). This fluid circulates in the narrow spaces between cells and through the cavities in the brain called [[Ventricular system|ventricles]], to nourish, support, and protect the brain tissue. [[Blood vessels]] enter the [[central nervous system]] through the perivascular space above the pia mater. The cells in the blood vessel walls are joined tightly, forming the [[blood–brain barrier]] which protects the brain from [[toxins]] that might enter through the blood.
Tumors of the meninges are [[meningioma]]s and are often benign.

===Brain matter===
The brains of humans and other [[vertebrates]] are composed of very soft tissue and a gelatin-like texture. Living brain tissue has a pink tint in color on the outside ([[grey matter]]), and nearly complete white on the inside ([[white matter]]), with subtle variations in color. Three separate brain areas make up most of the brain's volume:
*[[telencephalon]] (cerebral hemispheres or [[cerebrum]])
*[[mesencephalon]] (midbrain)
*[[cerebellum]]

These areas are composed of two broad classes of cells: [[neurons]] and [[glia]]. These two types are equally numerous in the brain as a whole, although [[glial cells]] outnumber [[neurons]] roughly 4 to 1 in the [[cerebral cortex]]. Glia come in several types, which perform a number of critical functions, including structural support, metabolic support, insulation, and guidance of development.

Primary tumors of the glial cells are called [[glioma]]s and often are malignant by the time they are diagnosed.

===Spinal cord and other tissues===
The [[pons]] in the [[brainstem]] is a specific region that consists of myelinated axons much like the spinal cord.
The [[thalamus]] and [[hypothalamus]] of the [[diencephalon]] also consist of neuron and glial cell tissue with the hypophysis ([[pituitary gland]]) and [[pineal gland]] (which is glandular tissue) attached at the bottom; tumors of the [[pituitary]] and [[pineal gland]] are often benign.
The [[medulla oblongata]] is at the start of the spinal cord and is composed mainly of neuron tissue enveloped in [[Schwann cells]] and meninges tissue. The [[spinal cord]] is made up of bundles of these [[axons]]. Glial cells such as Schwann cells in the periphery or, within the cord itself, [[oligodendrocytes]], wrap themselves around the axon, thus promoting faster transmission of electrical signals and also providing for general maintenance of the environment surrounding the cord, in part by shuttling different compounds around in response to injury or other stimulus.

==Diagnosis==
[[File:Postermass.png|thumb|A posterior fossa tumor leading to mass effect and midline shift]]

Most of the brain is separated from the blood by the [[blood-brain barrier]] (BBB), which exerts a restrictive control as to which substances are allowed to pass. Therefore, many tracers that reach tumors in the body very easily would only reach brain tumors once there is a disruption of the BBB. Thus the disruption of the BBB, which can be detected by a MRI and CT, is regarded as the main diagnostic indicator for malignant gliomas, meningiomas, and brain metastases.<ref name="Herholz">{{cite journal |last1=Herholz |first1=Karl |last2=Langen |first2=Karl-Josef |last3=Schiepers |first3=Christiaan |last4=Mountz |first4=James M. |title=Brain Tumors |journal=Seminars in Nuclear Medicine |volume=42 |issue=6 |pages=356–70 |year=2012 |pmid=23026359 |pmc=3925448 |doi=10.1053/j.semnuclmed.2012.06.001 }}</ref>

Although there is no specific or singular clinical symptom or sign for any brain tumors, the presence of a combination of symptoms and the lack of corresponding clinical indications of infections or other causes can be an indicator to redirect diagnostic investigation towards the possibility of an intracranial neoplasm. Brain tumors have similar characteristics and obstacles when it comes to diagnosis and therapy with tumors located elsewhere in the body. However, they create specific issues that follow closely to the properties of the organ they are in.<ref name="Herholz" />

The diagnosis will often start by taking a [[medical history]] noting medical antecedents, and current symptoms. Clinical and laboratory investigations will serve to exclude infections as the cause of the symptoms. Examinations in this stage may include the eyes, [[otolaryngology|otolaryngological]] (or ENT) and electrophysiological exams. The use of [[electroencephalography]] (EEG) often plays a role in the diagnosis of brain tumors.

Swelling, or obstruction of the passage of [[cerebrospinal fluid]] (CSF) from the brain may cause (early) signs of increased [[intracranial pressure]] which translates clinically into [[headaches]], [[vomiting]], or an altered state of [[consciousness]], and in children changes to the diameter of the [[human skull|skull]] and bulging of the [[fontanelle]]s. More complex symptoms such as endocrine dysfunctions should alarm doctors not to exclude brain tumors.

A bilateral temporal [[visual field]] defect (due to compression of the [[optic chiasm]]) or dilatation of the pupil, and the occurrence of either slowly evolving or the sudden onset of [[focal neurologic symptom]]s, such as [[cognitive]] and [[behavioral]] impairment (including impaired judgment, memory loss, lack of recognition, spatial orientation disorders), [[Wiktionary:personality|personality]] or emotional changes, [[hemiparesis]], [[hypoesthesia]], [[aphasia]], [[ataxia]], [[visual field]] impairment, impaired sense of smell, impaired hearing, [[facial paralysis]], [[diplopia|double vision]], or more severe symptoms such as [[tremor]]s, paralysis on one side of the body [[hemiplegia]], or (epileptic) seizures in a patient with a negative history for epilepsy, should raise the possibility of a brain tumor.

===Imaging===
[[Medical imaging]] plays a central role in the diagnosis of brain tumors. Early imaging methods—invasive and sometimes dangerous— such as [[pneumoencephalography]] and cerebral [[angiography]] have been abandoned in favor of non-invasive, high-resolution techniques, especially [[magnetic resonance imaging]] (MRI) and [[computed tomography]] (CT) scans. Neoplasms will often show as differently colored masses (also referred to as processes) in CT or MRI results.

* Benign brain tumors often show up as hypodense (darker than brain tissue) mass lesions on CT scans. On MRI, they appear either hypodense or isointense (same intensity as brain tissue) on [[spin-lattice relaxation|T1-weighted]] scans, or hyperintense (brighter than brain tissue) on [[spin-spin relaxation|T2-weighted]] MRI, although the appearance is variable.
*[[Contrast agent]] uptake, sometimes in characteristic patterns, can be demonstrated on either CT or MRI scans in most malignant primary and metastatic brain tumors.
*Pressure areas where the brain tissue has been compressed by a tumor also appear hyperintense on T2-weighted scans and might indicate the presence a diffuse neoplasm due to an unclear outline. Swelling around the tumor known as ''peritumoral edema'' can also show a similar result.

This is because these tumors disrupt the normal functioning of the BBB and lead to an increase in its permeability. However, it is not possible to diagnose high- versus low-grade gliomas based on enhancement pattern alone.

The definitive [[medical diagnosis|diagnosis]] of brain tumor can only be confirmed by [[histology|histological examination]] of [[tumor]] [[Biological tissue|tissue]] samples obtained either by means of brain [[biopsy]] or open [[surgery]]. The histological examination is essential for determining the appropriate treatment and the correct [[prognosis]]. This examination, performed by a [[pathologist]], typically has three stages: interoperative examination of fresh tissue, preliminary microscopic examination of prepared tissues, and follow-up examination of prepared tissues after immunohistochemical staining or genetic analysis.

===Pathology===
[[Image:Oligodendroglioma1 high mag.jpg|thumb|[[Micrograph]] of an [[oligodendroglioma]], a type of brain cancer. Brain [[biopsy]]. [[H&E stain]].]]
Tumors have characteristics that allow determination of malignacy and how they will evolve, and determining these characteristics will allow the medical team to determine the management plan.

[[Anaplasia]] or dedifferentiation: loss of differentiation of cells and of their orientation to one another and blood vessels, a characteristic of anaplastic tumor tissue. Anaplastic cells have lost total control of their normal functions and many have deteriorated cell structures. Anaplastic cells often have abnormally high nuclear-to-cytoplasmic ratios, and many are multinucleated. Additionally, the nuclei of anaplastic cells are usually unnaturally shaped or oversized. Cells can become anaplastic in two ways: neoplastic tumor cells can dedifferentiate to become anaplasias (the dedifferentiation causes the cells to lose all of their normal structure/function), or cancer stem cells can increase in their capacity to multiply (i.e., uncontrollable growth due to failure of differentiation).

[[Atypia]]: an indication of abnormality of a cell (which may be indicative for malignancy). Significance of the abnormality is highly dependent on context.

[[Neoplasia]]: the (uncontrolled) division of cells. As such, neoplasia is not problematic but its consequences are: the uncontrolled division of cells means that the mass of a neoplasm increases in size, and in a confined space such as the intracranial cavity this quickly becomes problematic because the mass invades the space of the brain pushing it aside, leading to compression of the brain tissue and increased intracranial pressure and destruction of [[Parenchyma|brain parenchyma]]. Increased intracranial pressure (ICP) may be attributable to the direct mass effect of the tumor, increased blood volume, or increased cerebrospinal fluid (CSF) volume, which may in turn have secondary symptoms.

[[Necrosis]]: the (premature) death of cells, caused by external factors such as infection, toxin or trauma. Necrotic cells send the wrong chemical signals which prevents [[phagocytes]] from disposing of the dead cells, leading to a buildup of dead tissue, cell debris and toxins at or near the site of the necrotic cells<ref name=necrs>{{MedlinePlus|002266|Necrosis}}</ref>

Arterial and venous [[hypoxia (medical)|hypoxia]], or the deprivation of adequate oxygen supply to certain areas of the brain, occurs when a tumor makes use of nearby blood vessels for its supply of blood and the neoplasm enters into competition for nutrients with the surrounding brain tissue.

More generally a neoplasm may cause release of metabolic end products (e.g., free radicals, altered electrolytes, neurotransmitters), and release and recruitment of cellular mediators (e.g., cytokines) that disrupt normal parenchymal function.

===Classification===

====Secondary brain tumors====
Secondary tumors of the brain are [[metastasis|metastatic]] and have invaded the brain from [[cancer]]s originating in other organs. This means that a cancerous neoplasm has developed in another organ elsewhere in the body and that cancer cells have leaked from that primary tumor and then entered the [[lymphatic system]] and [[blood vessels]]. They then circulate through the bloodstream, and are deposited in the brain. There, these cells continue growing and dividing, becoming another invasive neoplasm of the primary cancer's tissue. Secondary tumors of the brain are very common in the terminal phases of patients with an incurable metastasized cancer; the most common types of cancers that bring about secondary tumors of the brain are [[lung cancer]], [[breast cancer]], malignant [[melanoma]], [[kidney cancer]], and [[colon cancer]] (in decreasing order of frequency).

Secondary brain tumors are more common than primary ones; in the United States there are about 170,000 new cases every year. Secondary brain tumors are the most common cause of tumors in the intracranial cavity. The [[human skull|skull]] bone structure can also be subject to a neoplasm that by its very nature reduces the volume of the intracranial cavity, and can damage the brain.<ref>{{MedlinePlusEncyclopedia|000769|Metastatic brain tumor}}</ref>

====By behavior====
Brain tumors or intracranial neoplasms can be [[cancerous]] (malignant) or non-cancerous (benign). However, the definitions of malignant or benign neoplasms differs from those commonly used in other types of cancerous or non-cancerous neoplasms in the body.
In cancers elsewhere in the body, three malignant properties differentiate benign tumors from malignant forms of cancer: benign tumors are self-limited and do not invade or metastasize. Characteristics of malignant tumors include:

* uncontrolled mitosis (growth by division beyond the normal limits)
* [[anaplasia]]: the cells in the neoplasm have an obviously different form (in size and shape). Anaplastic cells display marked [[pleomorphism (cytology)|pleomorphism]]. The [[cell nuclei]] are characteristically extremely hyperchromatic (darkly stained) and enlarged; the nucleus might have the same size as the [[cytoplasm]] of the cell (nuclear-cytoplasmic ratio may approach 1:1, instead of the normal 1:4 or 1:6 ratio). [[Giant cells]] – considerably larger than their neighbors – may form and possess either one enormous nucleus or several nuclei ([[syncytium|syncytia]]). Anaplastic nuclei are variable and bizarre in size and shape.
* invasion or infiltration (medical literature uses these terms as synonymous equivalents. However, for clarity, the articles that follow adhere to a convention that they mean slightly different things; this convention is not followed outside these articles):
** Invasion or invasiveness is the spatial expansion of the tumor through uncontrolled mitosis, in the sense that the neoplasm invades the space occupied by adjacent tissue, thereby pushing the other tissue aside and eventually compressing the tissue. Often these tumors are associated with clearly outlined tumors in imaging.
** Infiltration is the behavior of the tumor either to grow (microscopic) tentacles that push into the surrounding tissue (often making the outline of the tumor undefined or diffuse) or to have tumor cells "seeded" into the tissue beyond the circumference of the tumorous mass; this does not mean that an infiltrative tumor does not take up space or does not compress the surrounding tissue as it grows, but an infiltrating neoplasm makes it difficult to say where the tumor ends and the healthy tissue starts.
* [[metastasis]] (spread to other locations in the body via lymph or blood).

Of the above malignant characteristics, some elements do not apply to primary neoplasms of the brain:
* Primary brain tumors rarely metastasize to other organs; some forms of primary brain tumors can metastasize but will not spread outside the intracranial cavity or the central spinal canal. Due to the BBB, cancerous cells of a primary neoplasm cannot enter the bloodstream and get carried to another location in the body. (Occasional isolated case reports suggest spread of certain brain tumors outside the central nervous system, e.g. bone metastasis of [[glioblastoma multiforme]].<ref>{{cite journal |vauthors=Frappaz D, Mornex F, Saint-Pierre G, Ranchere-Vince D, Jouvet A, Chassagne-Clement C, Thiesse P, Mere P, Deruty R | title = Bone metastasis of glioblastoma multiforme confirmed by fine needle biopsy | journal = Acta Neurochirurgica | volume = 141 | issue = 5 | pages = 551–552 | year = 1999 | pmid = 10392217 | doi = 10.1007/s007010050342 }}</ref>)
* Primary brain tumors generally are invasive (i.e. they will expand spatially and intrude into the space occupied by other brain tissue and compress those brain tissues); however, some of the more malignant primary brain tumors will infiltrate the surrounding tissue.

Of numerous [[Grading of the tumors of the central nervous system|grading systems]] in use for the classification of tumor of the central nervous system, the [[World Health Organization]] [[Grading of the tumors of the central nervous system#WHO grading|(WHO) grading system]] is commonly used for astrocytoma. Established in 1993 in an effort to eliminate confusion regarding diagnoses, the WHO system established a four-tiered histologic grading guideline for astrocytomas that assigns a grade from 1 to 4, with 1 being the least aggressive and 4 being the most aggressive.

===Types===
Tumors can be [[benign]] or [[malignant]], can occur in different parts of the brain, and may be primary or secondary. A primary tumor is one that has started in the brain, as opposed to a [[metastasis|metastatic]] tumor, which is something that has spread to the brain from another part of the body.<ref>{{cite web|url=http://www.cancer.gov/cancertopics/wyntk/brain/page1|title=What you need to know about brain tumors|accessdate=25 February 2012|publisher=National Cancer Institute}}</ref> The incidence of metastatic tumors are more prevalent than primary tumors by 4:1.<ref>{{cite journal |author=Merrel RT |journal=Dis Mon. |date=Dec 2012 |volume=58 |issue=12 |pages=678–89 |doi=10.1016/j.disamonth.2012.08.009 |pmid=23149521 |title=Brain tumors.}}</ref> Tumors may or may not be [[symptomatic]]: some tumors are discovered because the patient has symptoms, others show up incidentally on an imaging scan, or at an autopsy.

The most common primary brain tumors are:<ref>{{Cite book | publisher = Springer | isbn = 978-1-84882-910-7 | editor = Lee, Joung H. |author1=Park, Bong Jin |author2=Kim, Han Kyu |author3=Sade, Burak |author4=Lee, Joung H. | chapter = Epidemiology | title = Meningiomas: Diagnosis, Treatment, and Outcome | year = 2009 | page = 11 }}
</ref>
* [[Gliomas]] (50.4%)
* [[Meningiomas]] (20.8%)
* [[Pituitary adenomas]] (15%)
* [[Nerve sheath tumors]] (8%)

These common tumors can also be organized according to tissue of origin as shown below:<ref>Sattar, Husain A. Pathoma.com</ref>{{vn|date=July 2014}}
{| class="wikitable"
|-
!
Tissue of origin
! Children !! Adults
|-
| [[Astrocytes]] || [[Pilocytic astrocytoma|Pilocytic Astrocytoma]] (PCA) || [[Glioblastoma multiforme|Glioblastoma Multiforme]] (GBM)
|-
| [[Oligodendrocytes]] || || [[Oligodendroglioma]]
|-
| [[Ependyma]] || [[Ependymoma]] ||
|-
| [[Neurons]] || [[Medulloblastoma]] ||
|-
| [[Meninges]] || || [[Meningioma]]
|}

====Specific types====
{{main article|WHO classification of the tumors of the central nervous system}}
[[Anaplastic astrocytoma]], [[Astrocytoma]], [[Central neurocytoma]], [[Choroid plexus carcinoma]], [[Choroid plexus papilloma]], [[Choroid plexus tumor]], [[Dysembryoplastic neuroepithelial tumour]], [[Ependymal tumor]], [[Fibrillary astrocytoma]], [[Giant-cell glioblastoma]], [[Glioblastoma multiforme]], [[Gliomatosis cerebri]], [[Gliosarcoma]], [[Hemangiopericytoma]], [[Medulloblastoma]], [[Medulloepithelioma]], [[Meningeal carcinomatosis]], [[Neuroblastoma]], [[Neurocytoma]], [[Oligoastrocytoma]], [[Oligodendroglioma]], [[Optic nerve sheath meningioma]], [[Pediatric ependymoma]], [[Pilocytic astrocytoma]], [[Pinealoblastoma]], [[Pineocytoma]], [[Pleomorphic anaplastic neuroblastoma]], [[Pleomorphic xanthoastrocytoma]], [[Primary central nervous system lymphoma]], [[Sphenoid wing meningioma]], [[Subependymal giant cell astrocytoma]], [[Subependymoma]], [[Trilateral retinoblastoma]].

==Treatment==
When a brain tumor is diagnosed, a medical team will be formed to assess the treatment options presented by the leading surgeon to the patient and his/her family. Given the location of primary solid neoplasms of the brain in most cases a "do-nothing" option is usually not presented. Neurosurgeons take the time to observe the evolution of the neoplasm before proposing a management plan to the patient and his/her relatives. These various types of treatment are available depending on neoplasm type and location and may be combined to give the best chances of survival:
* Surgery: complete or partial resection of the tumor with the objective of removing as many tumor cells as possible.
* Radiotherapy: the most commonly used treatment for brain tumors; the tumor is irradiated with beta, x rays or gamma rays.
* Chemotherapy: is a treatment option for cancer, however it is not always used to treat brain tumors as the blood-brain barrier can prevent some drugs from reaching the cancerous cells.
* A variety of experimental therapies are available through clinical trials.

Survival rates in primary brain tumors depend on the type of tumor, age, functional status of the patient, the extent of surgical tumor removal and other factors specific to each case.<ref>{{cite journal |last1=Nicolato |first1=Antonio |last2=Gerosa |first2=Massimo A. |last3=Fina |first3=Paolo |last4=Iuzzolino |first4=Paolo |last5=Giorgiutti |first5=Fabrizia |last6=Bricolo |first6=Albino |title=Prognostic factors in low-grade supratentorial astrocytomas: A uni-multivariate statistical analysis in 76 surgically treated adult patients |journal=Surgical Neurology |volume=44 |issue=3 |pages=208–21; discussion 221–3 |year=1995 |pmid=8545771 |doi=10.1016/0090-3019(95)00184-0 }}</ref>

===Surgery===
The primary and most desired course of action described in medical literature is surgical removal (resection) via [[craniotomy]]. Minimally invasive techniques are becoming the dominant trend in neurosurgical oncology.<ref>{{cite journal |vauthors=Spetzler RF, Sanai N | title = The quiet revolution: Retractorless surgery for complex vascular and skull base lesions | journal = Journal of Neurosurgery | volume = 116 | issue = 2 | pages = 291–300 | year = 2012 | pmid = 21981642 | pmc = | doi = 10.3171/2011.8.JNS101896 }}</ref> The prime remediating objective of surgery is to remove as many tumor cells as possible, with complete removal being the best outcome and [[cytoreduction]] ("debulking") of the tumor otherwise. In some cases access to the tumor is impossible and impedes or prohibits surgery.

Many [[meningiomas]], with the exception of some tumors located at the skull base, can be successfully removed surgically.
Most [[pituitary adenoma]]s can be removed surgically, often using a minimally invasive approach through the [[nasal cavity]] and skull base (trans-nasal, trans-sphenoidal approach). Large [[pituitary adenoma]]s require a [[craniotomy]] (opening of the skull) for their removal. Radiotherapy, including [[stereotactic]] approaches, is reserved for inoperable cases.

Several current research studies aim to improve the surgical removal of brain tumors by labeling tumor cells with [[Aminolevulinic acid|5-aminolevulinic acid]] that causes them to [[Fluorescence|fluoresce]].<ref name="Brain tumor clinical trials database">{{cite web |url= http://www.cliniclog.com/brain_tumour_trials.php |title=Introduction to brain cancer |work=cliniclog.com |author=Paul Brennan |accessdate=19 December 2011|date=4 August 2008}}</ref> 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.

Any person undergoing brain surgery may suffer from [[epilepsy|epileptic seizures]]. These can take the form of either [[absence seizures]] or [[tonic-clonic seizures]]. Medication can lessen and sometimes prevent these attacks.

Multiple metastatic tumors are generally treated with radiotherapy and chemotherapy rather than surgery and the prognosis in such cases is determined by the primary tumor, and is generally poor.

===Radiation therapy===
The goal of radiation therapy is to kill tumor cells while leaving normal brain tissue unharmed. In standard [[external beam radiation therapy]], multiple treatments of standard-dose "fractions" of radiation are applied to the brain. This process is repeated for a total of 10 to 30 treatments, depending on the type of tumor. This additional treatment provides some patients with improved outcomes and longer survival rates.

[[Radiosurgery]] is a treatment method that uses computerized calculations to focus radiation at the site of the tumor while minimizing the radiation dose to the surrounding brain. Radiosurgery may be an adjunct to other treatments, or it may represent the primary treatment technique for some tumors. Forms used include [[stereotactic]] radiosurgery, such as [[Gamma knife]], [[Cyberknife]] or [[Novalis radiosurgery|Novalis Tx]] [[radiosurgery]].<ref>{{cite web |url=http://www.sdcyberknife.com/comparison.htm |title=Radiosurgery treatment comparisons – Cyberknife, Gamma knife, Novalis Tx |accessdate=22 July 2014}}</ref>{{medrs|date=July 2014}}

[[Radiotherapy]] may be used following, or in some cases in place of, resection of the tumor. Forms of radiotherapy used for brain cancer include [[external beam radiation therapy]], the most common, and [[brachytherapy]] and [[proton therapy]], the last especially used for children.

Radiotherapy is the most common treatment for secondary brain tumors. The amount of radiotherapy depends on the size of the area of the brain affected by cancer. Conventional external beam "whole-brain radiotherapy treatment" (WBRT) or "whole-brain irradiation" may be suggested if there is a risk that other secondary tumors will develop in the future.<ref>{{cite web |publisher=Cancer Research UK |url=http://www.cancerhelp.org.uk/help/default.asp?page=5301 |title=Treating secondary brain tumours with WBRT |accessdate=5 June 2012}}</ref> Stereotactic radiotherapy is usually recommended in cases involving fewer than three small secondary brain tumors.

People who receive stereotactic radiosurgery (SRS) and whole-brain radiation therapy (WBRT) for the treatment of metastatic brain tumors have more than twice the risk of developing learning and memory problems than those treated with SRS alone.<ref>{{cite web |publisher=MD Anderson Cancer Center |url=http://www.mdanderson.org/diseases/braincancer/display.cfm?id=8f11775f-75bb-4d7b-b3ac46878a1d56d0&method=displayfull&pn=00c8a30f-c468-11d4-80fb00508b603a14 |title=Whole Brain Radiation increases risk of learning and memory problems in cancer patients with brain metastases |accessdate=5 June 2012 }}</ref><ref>{{cite web |publisher=International RadioSurgery Association |url=http://www.irsa.org/metastatic_tumors.html |title=Metastatic brain tumors |accessdate=5 June 2012}}</ref>

===Chemotherapy===
Patients undergoing chemotherapy are administered drugs designed to kill tumor cells. Although chemotherapy may improve overall survival in patients with the most malignant primary brain tumors, it does so in only about 20 percent of patients. Chemotherapy is often used in young children instead of radiation, as radiation may have negative effects on the developing brain. The decision to prescribe this treatment is based on a patient's overall health, type of tumor, and extent of the cancer. The toxicity and many side effects of the drugs, and the uncertain outcome of chemotherapy in brain tumors puts this treatment further down the line of treatment options with surgery and radiation therapy preferred.

UCLA Neuro-Oncology publishes real-time survival data for patients with a diagnosis of glioblastoma multiforme. They are the only institution in the United States that displays how brain tumor patients are performing on current therapies. They also show a listing of chemotherapy agents used to treat high-grade glioma tumors.<ref>{{cite web |publisher=UCLA Neuro-Oncology Program |url=http://www.neurooncology.ucla.edu/Performance/GlioblastomaMultiforme.aspx |title=How Our Patients Perform: Glioblastoma Multiforme |accessdate=5 June 2012 }}</ref>

===Other===
A [[Shunt (medical)|shunt]] may be used to relieve symptoms caused by [[intracranial pressure]], by reducing the build-up of fluid ([[hydrocephalus]]) caused by the blockage of the free flow of [[cerebrospinal fluid]].<ref>{{cite web|author=Dalvi A |url=http://www.emedicinehealth.com/normal_pressure_hydrocephalus/page9_em.htm |title=Normal Pressure Hydrocephalus Causes, Symptoms, Treatment |work=eMedicineHealth |publisher=Emedicinehealth.com |accessdate=17 February 2012}}</ref>

==Prognosis==
The prognosis of brain cancer depends on the type of cancer diagnosed. Medulloblastoma has a good prognosis with [[Medulloblastoma#Treatment and prognosis|chemotherapy, radiotherapy, and surgical resection]] while glioblastoma multiforme has a median survival of only 12 months even with aggressive [[chemoradiotherapy]] and surgery. Brainstem gliomas have the poorest prognosis of any form of brain cancer, with most patients dying within one year, even with therapy that typically consists of radiation to the tumor along with [[corticosteroid]]s. However, one type, focal brainstem gliomas in children, seems open to exceptional prognosis and long-term survival has frequently been reported.<ref>{{cite web|url=http://www.childhoodbraintumor.org/index.php?option=com_content&view=article&id=57:brain-stem-gliomas-in-childhood&catid=34:brain-tumor-types-and-imaging&Itemid=53 |title=Brain Stem Gliomas in Childhood |publisher=Childhoodbraintumor.org |accessdate=17 February 2012}}</ref>

===Glioblastoma multiforme===
{{Main article|Glioblastoma multiforme}}
Glioblastoma multiforme is the most aggressive ([[grading of the tumors of the central nervous system|grade IV]]) and most common form of a malignant brain tumor. Even when aggressive multimodality therapy consisting of radiotherapy, chemotherapy, and surgical excision is used, median survival is only 12–17 months. Standard therapy for glioblastoma multiforme consists of maximal surgical [[Segmental resection|resection]] of the tumor, followed by radiotherapy between two and four weeks after the [[craniotomy|surgical procedure]] to remove the cancer, then by [[temozolomide|chemotherapy]]. Most patients with glioblastoma take a [[corticosteroid]], typically [[dexamethasone]], during their illness to relieve symptoms. Experimental treatments include [[radiosurgery#Gamma Knife|gamma knife radiosurgery]],<ref>
{{cite web|url=http://brain.mgh.harvard.edu/patientguide.htm |title=GBM Guide – MGH Brain Tumor Center |publisher=Brain.mgh.harvard.edu |accessdate=17 February 2012}}
</ref> [[boron neutron capture therapy]] and [[gene therapy]].<ref>{{cite journal |author1=Chien-Kuo Tai |author2=Noriyuki Kasahara |url=http://www.nhhs.net/ourpages/auto/2009/3/25/49144229/Ram_s%20second%20paper.pdf |title=Replication-competent retrovirus vectors for cancer gene therapy |journal=Frontiers in Bioscience |volume=13 |pages=3083–3095 |date=1 January 2008 |pmid=17981778 |doi=10.2741/2910}}</ref><ref>{{cite journal |vauthors=Murphy AM, Rabkin SD | date = Apr 2013 | title = Current status of gene therapy for brain tumors | url = | journal = Transl. Res. | volume = 161 | issue = 4| pages = 339–54 | doi = 10.1016/j.trsl.2012.11.003 | pmid = 23246627 }}</ref>

===Oligodendrogliomas===
{{Main article|Oligodendroglioma}}
[[Oligodendroglioma]]s are incurable but slowly progressive malignant brain tumors. They can be treated with [[Segmental resection|surgical resection]], [[chemotherapy]], [[radiotherapy]] or a combination. For some suspected low-grade (grade II) tumors, only a course of watchful waiting and symptomatic therapy is opted for. These tumors show a high frequency of co-deletions of the p and q arms of [[chromosome 1 (human)|chromosome 1]] and [[chromosome 19 (human)|chromosome 19]] respectively (1p19q co-deletion) and have been found to be especially chemosensitive with one report claiming them to be one of the most chemosensitive tumors.<ref>{{cite journal |vauthors=Ty AU, See SJ, Rao JP, Khoo JB, Wong MC |title=Oligodendroglial tumor chemotherapy using "decreased-dose-intensity" PCV: a Singapore experience |journal=Neurology |volume=66 |issue=2 |pages=247–9 |date=January 2006 |pmid=16434664 |doi=10.1212/01.wnl.0000194211.68164.a0 |url=http://www.neurology.org/cgi/content/abstract/66/2/247 }}</ref> A median survival of up to 16.7 years has been reported for grade II oligodendrogliomas.<ref>{{cite web|url=http://www.neurology.org |title=Neurology |publisher=Neurology |accessdate=17 February 2012}}</ref>

==Epidemiology==
Figures for incidences of cancers of the brain show a significant difference between more- and less-developed countries (the less-developed countries have lower incidences of tumors of the brain),<ref>{{cite journal |vauthors=Bondy ML, Scheurer ME, Malmer B, etal | year = 2008 | title = Brain Tumor Epidemiology: Consensus from the Brain Tumor Epidemiology Consortium (BTEC) | url = | journal = Cancer | volume = 113 | issue = 7 Suppl | pages = 1953–1968 | doi = 10.1002/cncr.23741 }}</ref>— this could be explained by undiagnosed tumor-related deaths (patients in extreme poor situations do not get diagnosed, simply because they do not have access to the modern diagnostic facilities required to diagnose a brain tumor) and by deaths caused by other poverty-related causes that preempt a patient's life before tumors develop or tumors become life-threatening. Nevertheless, studies{{which|date=November 2012}} suggest that certain forms of primary brain tumors are more prevalent among certain groups of the population.

The incidence of low-grade astrocytoma has not been shown to vary significantly with nationality. However, studies examining the incidence of malignant [[central nervous system]] (CNS) tumors have shown some variation with national origin. Since some high-grade lesions arise from low-grade tumors, these trends are worth mentioning. Specifically, the incidence of CNS tumors in the United States, Israel, and the Nordic countries is relatively high, while Japan and Asian countries have a lower incidence. These differences probably reflect some biological differences as well as differences in pathologic diagnosis and reporting.<ref name=gallo>{{cite journal|vauthors=Jallo GI, Benardete EA |title=Low-Grade Astrocytoma |date=January 2010 |url=http://emedicine.medscape.com/article/1156429-overview}}</ref>
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{{cite journal |author=Ana M Crespo-Rodríguez; James G Smirniotopoulos; Elisabeth J Rushing |title=MR and CT imaging of 24 pleomorphic xanthoastrocytomas (PXA) and a review of the literature. |journal= Neuroradiology |volume=49 |issue= 4|pages=307–15 |date=April 2007 |pmid=17205313 |doi= 10.1007/s00234-006-0191-z|url=http://www.biomedsearch.com/nih/MR-CT-imaging-24-pleomorphic/17205313.html}}
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Worldwide data on incidence of cancer can be found at the [[WHO]] (World Health Organisation) and is handled by the IARC ([[International Agency for Research on Cancer]]) located in France.<ref>{{cite web |url=http://www-dep.iarc.fr |title=CANCERMondial |publisher=International Agency for Research on Cancer |accessdate=17 February 2012}}</ref>
<!-- following tables were extracted from the online database GloboCancer :
*[[Regional Summary of Occurence of cancers of the Brain & nervous system in Women]],
*[[Regional Summary of Occurence of cancers of the Brain & nervous system in Men]],
*[[Country based Incidence Rate of cancers of the Brain & nervous system in Women]],
*[[Country based Incidence Rate of cancers of the Brain & nervous system in Men]]
Some conclusions can be drawn from these figures. -->

===United States===
For the United States in the year 2005, it was projected that there would be 43,800 new cases of brain tumors <ref>{{cite web|url=http://www.cbtrus.org/reports/2005-2006/2006report.pdf |title=Central Brain Tumor Registry of the United States, Primary Brain Tumors in the United States, Statistical Report, 2005–2006 |accessdate=23 July 2014}}</ref><ref name=r1>{{cite journal |vauthors=Greenlee RT, Murray T, Bolden S, Wingo PA | title = Cancer statistics, 2000 | journal = CA Cancer J Clin | volume = 50 | issue = 1 | pages = 7–33 | year = 2000 | pmid = 10735013 | doi = 10.3322/canjclin.50.1.7 }}</ref>
which accounted for less than 1 percent of all cancers, 2.4 percent of all cancer deaths,<ref name=r2>{{cite web |publisher=American Cancer Society |url=http://www.cancer.org/Cancer/BrainCNSTumorsinAdults/DetailedGuide/brain-and-spinal-cord-tumors-in-adults-key-statistics |title=What are the key statistics about brain and spinal cord tumors? |date=May 1, 2012 }}</ref> and 20–25 percent of pediatric cancers.<ref name=r2/><ref>{{cite journal |vauthors=Chamberlain MC, Kormanik PA | title = Practical guidelines for the treatment of malignant gliomas | journal = West. J. Med. | volume = 168 | issue = 2 | pages = 114–20 | date = February 1998 | pmid = 9499745 | pmc = 1304839 }}
</ref> Ultimately, it is estimated there are 13,000 deaths per year in the United States alone as a result of brain tumors.<ref name=r1/>

===UK===
Brain, other CNS or intracranial tumors are the ninth most common cancer in the UK (around 10,600 people were diagnosed in 2013), and it is the eighth most common cause of cancer death (around 5,200 people died in 2012).<ref>{{cite web|title=Brain, other CNS and intracranial tumours statistics|url=http://www.cancerresearchuk.org/cancer-info/cancerstats/types/brain/|website=Cancer Research UK|accessdate=27 October 2014}}</ref>

==Research==

===Immunotherapy===
[[Cancer immunotherapy]] is being actively studied. For malignant gliomas no therapy has been shown to improve life expectancy as of 2015.<ref>{{cite journal|last1=Bloch|first1=O|title=Immunotherapy for malignant gliomas.|journal=Cancer Treatment and Research|date=2015|volume=163|pages=143–58|pmid=25468230|doi=10.1007/978-3-319-12048-5_9}}</ref>

===Vesicular stomatitis virus===
{{See also|Oncolytic virus}}
In 2000, researchers used the [[vesicular stomatitis virus]], or VSV, to infect and kill cancer cells without affecting healthy cells.<ref>{{cite journal |vauthors=Auer R, Bell JC |url=http://www.futuremedicine.com/doi/full/10.2217/fon.11.134 |title=Oncolytic viruses: smart therapeutics for smart cancers |journal=Future Oncology |date=January 2012 |volume=8 |issue=1 |pages=1–4 |doi=10.2217/fon.11.134 |pmid=22149027}}</ref><ref>{{cite journal |author=Garber K |url=http://jnci.oxfordjournals.org/content/98/5/298.full |title=China Approves World's First Oncolytic Virus Therapy For Cancer Treatment |journal=J Natl Cancer Inst |date=1 March 2006 |volume=98 |issue=5 |pages=298–300 |doi=10.1093/jnci/djj111 |pmid=16507823}}</ref>

The initial discovery of the virus' [[oncolytic]] properties were limited to only a few types of cancer. Several independent studies have identified many more types susceptible to the virus, including [[glioblastoma multiforme]] cancer cells, which account for the majority of brain tumors.

In 2008, researchers artificially engineered strains of VSV that were less cytotoxic to normal cells. This advance allows administration of the virus without coadministration with [[interferon]]. Consequently, administration of the virus can be given intravenously or through the [[olfactory nerve]]. In the research, a human brain tumor was implanted into [[mouse|mice]] brains.

Research on virus treatment like this has been conducted for some years, but no other viruses have been shown to be as efficient or specific as the VSV mutant strains.

===Retroviral replicating vectors===
[[Image:Tumor BrainstemGlioma2.JPG|thumb|A [[brainstem]] [[glioma]] in four-year-old. MRI, [[sagittal]], without contrast]]
Led by Prof. Nori Kasahara, researchers from [[University of Southern California|USC]], who are now at [[University of California, Los Angeles|UCLA]], reported in 2001 the first successful example of applying the use of [[Viral vector|retroviral replicating vectors]] towards transducing cell lines derived from solid tumors.<ref>{{cite journal |vauthors=Logg CR, Tai CK, Logg A, Anderson WF, Kasahara N |journal=Human Gene Therapy |date=20 May 2001 |doi=10.1089/104303401750195881 |title=A uniquely stable replication-competent retrovirus vector achieves efficient gene delivery in vitro and in solid tumors |volume=12 |issue=8 |pages=921–932 |pmid=11387057 }}</ref> Building on this initial work, the researchers applied the technology to ''in vivo'' models of cancer and in 2005 reported a long-term survival benefit in an experimental brain tumor animal model.<ref>{{cite journal |vauthors=Tai CK, Wang WJ, Chen TC, Kasahara N |journal=Molecular Therapy |date=November 2005 |doi=10.1016/j.ymthe.2005.03.017 |url=http://www.nature.com/mt/journal/v12/n5/full/mt20051365a.html |title=Single-shot, multicycle suicide gene therapy by replication-competent retrovirus vectors achieves long-term survival benefit in experimental glioma |volume=12 |issue=5 |pages=842–851 |pmid=16257382 }}</ref>{{medrs|date=July 2014}} Subsequently, in preparation for human clinical trials, this technology was further developed by Tocagen (a pharmaceutical company primarily focused on brain cancer treatments) as a combination treatment ([[Toca 511 & Toca FC]]). This has been under investigation since 2010 in a Phase I/II clinical trial for the potential treatment of recurrent high-grade glioma including glioblastoma multiforme (GBM) and anaplastic astrocytoma. No results have yet been published.<ref>{{cite web |publisher=Clinical Trials.gov |date=July 2014 |url=http://clinicaltrials.gov/ct2/show/NCT01156584?term=toca+511&rank=1 |title=A Study of a Retroviral Replicating Vector Administered to Subjects With Recurrent Malignant Glioma }}</ref>

==Children==
{{update|section|PMID 23436013|date=July 2014}}
In the USA, about 2,000 children and adolescents younger than 20 years of age are diagnosed with malignant brain tumors each year. Higher incidence rates were reported in 1985–1994 than in 1975–1983. There is some debate as to the reasons; one theory is that the trend is the result of improved diagnosis and reporting, since the jump occurred at the same time that [[Magnetic resonance imaging|MRIs]] became available widely, and there was no coincident jump in [[Mortality rate|mortality]]. The central nervous system cancer survival rate in children is approximately 60%. The rate varies with the type of cancer and the age of onset: younger patients have higher mortality.<ref>{{cite web |url= http://seer.cancer.gov/publications/childhood/cns.pdf |title=CNS and Miscellaneous Intracranial and Instraspinal Neoplasms |accessdate=4 December 2008 |vauthors=Gurney JG, Smith MA, Bunin GR |work=SEER Pediatric Monograph |publisher=[[National Cancer Institute]]|pages=51–57 |quote=In the US, approximately 2,200 children and adolescents younger than 20 years of age are diagnosed with malignant central nervous system tumors each year. More than 90 percent of primary CNS malignancies in children are located within the brain. }}</ref>

In children under 2, about 70% of brain tumors are [[medulloblastoma]]s, [[ependymoma]]s, and low-grade [[glioma]]s. Less commonly, and seen usually in infants, are [[teratoma]]s and [[ATRT|atypical teratoid rhabdoid tumor]]s.<ref>{{cite web |url=http://www.childhoodbraintumor.org/brain-tumor-types-and-imaging/163-infantile-brain-tumors.html |title=Infantile Brain Tumors |author=Rood BR |publisher=The Childhood Brain Tumor Foundation |accessdate=23 July 2014}}</ref> [[Germ cell tumor]]s, including teratomas, make up just 3% of pediatric primary brain tumors, but the worldwide incidence varies significantly.<ref name=pmid18586924>{{cite journal |vauthors=Echevarría ME, Fangusaro J, Goldman S | title = Pediatric central nervous system germ cell tumors: a review | journal = Oncologist | volume = 13 | issue = 6 | pages = 690–9 | date = June 2008 | pmid = 18586924 | doi = 10.1634/theoncologist.2008-0037 }}</ref>

In the UK, 429 children aged 14 and under are diagnosed with a brain tumour on average each year, and 563 children and young people under the age of 19 are diagnosed.<ref>{{cite web |url=https://www.thebraintumourcharity.org/understanding-brain-tumours/symptoms-and-information/childhood-brain-tumours/| title= About childhood brain tumours |accessdate=16 June 2016}}</ref>

==See also==
*[[Timeline of brain cancer]]
*[[List of brain tumor patients|List of notable brain tumor patients]]

==References==
{{Reflist|2}}

==External links==
{{commons category|Brain neoplasms}}
* {{DMOZ|/Health/Conditions_and_Diseases/Cancer/Brain_and_CNS/|Brain and CNS cancers}}
* [http://www.cancerhelp.org.uk/type/brain-tumour/ Brain tumour information] from [[Cancer Research UK]]
* [http://www.bccancer.bc.ca/HPI/CancerManagementGuidelines/NeuroOncology/default.htm Neuro-Oncology:] Cancer Management Guidelines
* [http://rad.usuhs.edu/medpix/kiosk_image.html?pt_id=13381&imageid=52032 MedPix Teaching File] MR Scans of Primary Brain Lymphoma, etc.

{{Nervous tissue tumors}}
{{Tumors}}

{{Authority control}}

{{DEFAULTSORT:Brain Tumor}}
[[Category:Disorders causing seizures]]
[[Category:Brain tumor]]
[[Category:RTT]]

Revision as of 13:24, 1 September 2016

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