Brain tumours is the generic name for a group of about 130 different diseases [cite] that are all caused by the uncontrolled growth of cells within the brain, spinal cord, or elsewhere within the central nervous system. Different types of brain tumour can be either benign or malignant. Although benign tumours tend to stay localised at the site at which they initially arise, they can be fatal if left untreated, and can occasionally become malignant. Malignant tumours are capable of spreading to other regions of the brain and central nervous system.
Brain tumours are generally named after the type of brain or nerve cell from which they developed, or the region of the brain in which they are growing (for example, tumours arising in cells called astrocytes are named astrocytomas, wheras tumours arising in the pituitary gland are called pituitary tumours). The most common brain tumours in adults are gliomas, which develop from cells called glial cells; they account for about 70 per cent of new cases in US adults. [1] In children, the most common form is medulloblastoma [ref].
Cancers that arise elsewhere in the body can also spread to the brain. These are called secondary brain tumours, and tend to behave and respond to similar treatments to the original (primary) cancer type from which they arose.
Brain tumours can cause a diverse range of symptoms, all of which are hard to tell apart from other more common conditions. These are divided into symptoms caused by the physical pressure inside the skull - including fits, persistent headaches and seizures - and others caused when a growing tumour the disruption of normal brain functioning - such as memory, personality and coordination problems.
The causes of brain tumours are still poorly understood. The only environmental cause recognised by the International Agency for Research on Cancer (IARC) is ionising radiation (for example, medical x-rays). The risk of developing the disease generally increases with age. However some forms are more common in children. The disease is also more common in people with certain inherited genetic conditions, such as neurofibramatosis.
Approximately 256,000 people worldwide are diagnosed with a malignant brain tumour each year [2].
Classification
editTumours of the brain and central nervous system are classified by a number of different systems and methods, and according to a number of different attributes.
The World Health Organisation's 'classification of tumours of the central nervous system' [3] classifies tumours according to their location or tissue of origin within the brain or central nervous system (as determined by CT or MRI imaging, see 'Diagnosis'). While essential for proper understanding of brain tumour epidemiology, such classification is not necessarily useful in the treatment and management of the disease.
Thus, an essential step in determining the best treatment for a patient is the analysis of a tumour sample using a microscope (histopathology), to assign a brain tumour's grade. Listed using Roman numerals from I to IV, tumour grade indicates the likely speed of growth and spread, i.e. a tumour's aggressiveness. Grade I tumours are considered the slowest growing, whereas grade IV are the fastest. However, grading is not always possible due to the fact that a tumour's position in the brain may make obtaining a tissue sample impossible. Approximately xx% of tumours are ungraded and listed in statistics as 'tumours of unknown/uncertain behaviour'.
Increasingly, in keeping with the general trend towards genetic and molecular classification of diseases, brain tumours are classified according to the specific molecular defects inside tumour cells. [4] This is leading to a new understanding of the difference between benign and malignant tumours, and on the origins and development of the disease.
Types of brain tumour
edit- Main article: List of types of brain tumour [need to create?]
Gliomas
editLooking at all age groups, around 45 out of 100 primary brain tumours originate in the glial cells that support nervous tissue, and are called gliomas. There are 3 main types of glioma:
- Astrocytoma (including glioblastoma multiforme - a grade IV astrocytoma)
- Oligodendroglioma
- Ependymoma
Meningiomas
editAbout 25 out of every 100 brain tumours originates in the tissues covering the nervous system (the meninges) and are termed meningiomas.
Pituitary adenomas
editTumours arising in the pituitary gland are termed pituitary adenomas, and account for about 15 per 100 brain tumours.
Nerve sheath tumour
editAbout 8 in 100 brain and CNS tumours are nerve sheath tumours, that arise from the myelin sheath surrounding nerve tissue.
Lymphomas
editAbout 5 in every 100 brain tumours originates in the immune cells that patrol the central nervous system (CNS) and are termed CNS lymphomas.
Other types
editOther forms of brain tumour can be extremely rare overall, but more common among children (for example, medulloblastoma, which is rare in adults but accounts for nearly 15 in every hundred children diagnosed with a malignant brain tumour).
Signs & symptoms
editThe symptoms of brain tumours are often hard to differentiate from other more common ailments, as well as other neurological conditions. Broadly speaking, they are divided into two categories - symptoms caused by the physical presence of a mass within the brain or central nervous system; and those caused by the disruption to normal neurological function by the growing tumour.
Symptoms caused by pressure
editThese include:
Headaches
editAbout 1 in 3 people with a brain tumour first go to their doctor with headaches. Typically, a headache caused by a brain tumour tends to be quite bad, although can be mild at first. They may last for a long time, starting with a severe headache receding throughout the day.
Fits (seizures)
editAbout 1 in 4 people diagnosed with a brain tumour are diagnosed with fits. These can manifest themselves in many ways, from fits in single limbs, to whole-body fits, and momentary unconsciousness. They can often be controlled with anti-epilepsy medicines.
Nausea
editAs with headaches, this may be more serious in the morning.
Drowsiness
editDrowsiness is often a symptom of a more advanced brain tumour, as progressive growth of the tumour increases tiredness. If untreated, this can lead to unconsciousness.
Visual problems
editProblems with sight are also a symptom of raised intracranial pressure caused by a brain tumour. They can include blurred vision, floating shapes, tunnel vision, or a loss of vision that comes and goes.
Symptoms caused by disruption of brain function
editThese are strongly dependent on the location of the tumour in the nervous system.
Frontal lobe
edit- Changes in personality
- Swearing or loss of inhibitions
- Apathy
- Difficulty with planning and organising
- Irritability or aggressiveness
- Weakness in part of the face, or on one side of the body
- Difficulty walking
- Loss of sense of smell
- Problems with sight or speech
Temporal lobe
edit- Forgetting words
- Difficulty finding the correct word
- Short-term memory loss
- Fits associated with strange feelings, smells or déjà vu
- Hearing voices
Parietal lobe
edit- Difficulty speaking or understanding what is said
- Problems with reading or writing
- Loss of feeling in part of the body
Occipital lobe
edit- Sight problems or loss of vision on one side
Cerebellum (hindbrain)
edit- Poor coordination
- Uncontrolled movement of the eyes
- Sickness
- Neck stiffness
- Dizziness
Brain stem
edit- Poor coordination
- Drooping eyelid or mouth on one side
- Difficulty swallowing
- Difficulty speaking
- Seeing double
Spinal cord
edit- Pain
- Numbness in part of the body
- Weakness in the legs or arms
- Loss of control of the bladder or bowe
Pituitary gland
edit- Irregular or infrequent periods
- Infertility in men and women
- Lack of energy
- Weight gain
- Mood swings
- High blood pressure
- Diabetes
- Enlarged hands and feet
Nerves controlling sight
edit- Failing sight
Hearing nerves
edit- Failing hearing
Meninges
edit- Headache
- Sickness
- Sight problems
- Problems with movement
Causes and risk factors
editKnown risk factors
editSuspected risk factors
editControversies
editDevelopment
editDepends on region in brain, can develop from many cell types.
Diagnosis
editAlthough 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
Treatment
editOutcomes
editDistribution
editAccording to the GLOBOCAN database [2], in 2012, for every 100,000 people worldwide, there were 3.4 cases of primary malignant brain and CNS tumours. Rates were higher in men (3.9 per 100,000) than in women (3.0 per 100,000). Overall, this represented an estimated 139,608 males and 116,605 females who were diagnosed worldwide with a primary malignant brain tumour in 2012, an overall total of just over 256,000 people.
Research directions
edit- ^ Wen, Patrick Y.; Kesari, Santosh (31 July 2008). "Malignant Gliomas in Adults". New England Journal of Medicine. 359 (5): 492–507. doi:10.1056/NEJMra0708126.
- ^ a b "GLOBOCAN 2012 v1.0 - Cancer Incidence and Mortality Worldwide: IARC CancerBase No. 11". GLOBOCAN. International Agency for Research on Cancer. Retrieved 2/19/2014.
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(help) - ^ Louis, DN; Ohgaki, H; Wiestler, OD; Cavenee, WK; Burger, PC; Jouvet, A; Scheithauer, BW; Kleihues, P (August 2007). "The 2007 WHO classification of tumours of the central nervous system". Acta neuropathologica. 114 (2): 97–109. PMID 17618441.
- ^ Kheirollahi, Majid; Dashti, Sepideh; Khalaj, Zahra; Nazemroaia, Fatemeh; Mahzouni, Parvin (2015). "Brain tumors: Special characters for research and banking". Advanced Biomedical Research. 4 (1): 4. doi:10.4103/2277-9175.148261.
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