KOCHI: Most brain tumours are not linked with any known risk factors and have no obvious cause. But there are a few factors that can raise the risk of brain tumours.
Radiation exposure
The best known environmental risk factor for brain tumours is radiation exposure, most often from radiation therapy to treat some other condition for example leukemia. These brain tumours usually develop around 10 to 15 years after the radiation. Radiation-induced tumours are still fairly rare. The possible risk from exposure to imaging tests, such as X-rays or CT scans, is not known for sure. However, the risk is negligibly small.
Immune system disorders and drug induced
People with impaired immune systems have an increased risk of developing lymphomas (cancers of lymphocytes) of the brain or spinal cord. Giving the cancer drug methotrexate into the fluid around the spinal cord (intrathecal methotrexate) for the treatment of leukaemia has been shown to increase the risk of brain tumours.
Post menopausal women who are taking hormone replacement therapy (HRT) or oral contraceptives may have a slightly increased risk of developing meningioma but more research is needed to confirm this.
Family history
In rare cases (5 per cent) brain cancers run in families and usually occur first when they are young. Some of these include Neurofibromatosis ,Tuberous sclerosis, Von Hippel-Lindau disease etc.
Other factors
Environmental factors such as exposure to solvents, pesticides, oil products, rubber, or vinyl chloride (a chemical used to manufacture plastics), petroleum products, and certain other chemicals have been linked with an increased risk of brain tumours.
Exposure to aspartame (a sugar substitute) and infection with certain viruses (EB virus, human CMV, polyoma virus) have been suggested as possible risk factors.
Factors with uncertain, controversial, or unproven effects on brain tumour risk
1) Cell phone use
Cell phones give off radiofrequency (RF) rays, a form of energy on the electromagnetic spectrum between FM radio waves and those used in microwave ovens, radar, and satellite stations. Cell phones do not give off ionizing radiation, the type that can cause cancer by damaging the DNA . In 2011, International Agency for Research on Cancer (IARC) classified mobile phone radiation as Group 2B - possibly carcinogenic. That means that there ‘could be some risk’ of carcinogenicity, so additional research needs to be conducted.
2) Diet, smoking and alcohol
Dietary N-nitroso compounds may raise the risk of both childhood and adult brain tumours. These compounds are formed in the body from nitrites or nitrates found in some cured meats, cigarette smoke, and cosmetics. Drinking alcohol doesn’t seem to affect the risk.
Warning signals
Tumours produce symptoms either due to compression or irritation of brain
l Headache occurring in later onset of life and gradually increasing in intensity. There can be a constant aching pain. Usually headache is maximum in the morning and the victim wakes up with severe headache
l Projectile vomiting mostly on waking up in the morning. Here the vomiting will not be preceded by nausea. Vomiting offers temporary relief to the headache.
l New onset seizures with can be focal seizures involving only part of the body or it can be generalised seizures.
l Weakness or numbness- progressively increasing and can involve only one limb or one side of the body.
l Visual problems especially when it involves the optic nerve or pituitary gland.
l Cognitive problems occurring suddenly like memory problems, behavioral changes, language problems , confusions etc
l Difficulty in speech, sudden gait disturbances, imbalance in coordination or weakness of facial muscles