Basic facts about brain tumours
Dr. Arun Oommen, Consultant Surgeon, Department of Neurosurgery
Brain tumor refers to formation of abnormal cells within the brain. There are two main types of brain tumors: cancerous(malignant) tumors and indolent(benign) tumors. Presentation may include headaches, seizures, problem with vision, vomiting, decreasing sensorium and mental changes. The headache is classically worst in the morning and relieved with vomiting. More specific problems may include difficulty in walking or speaking.
Most brain tumors 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 tumors. . Even if a person has a risk factor, it is often very hard to know how much it contributed to the tumor.
The best known environmental risk factor for brain tumors is radiation exposure most often from radiation therapy to treat some other condition., Before the risks of radiation were known, children with ringworm of the scalp (a fungal infection) were sometimes treated with low-dose radiation therapy, which increased their risk of brain tumors as they got older. Nowadays most radiation-induced brain tumors are caused by radiation to the head given to treat other cancers esp treatment for leukemia. These brain tumors usually develop around 10 to 15 years after the radiation. Radiation-induced tumors are still fairly rare, but because of the increased risk (as well as the other side effects), radiation therapy to the head is only given after carefully weighing the possible benefits and risks. The possible risk from exposure to imaging tests, such as x-rays or CT scans, is not known for sure. Some studies claim that it may increase risk for tumours like meningiomas and gliomas. These tests use much lower levels of radiation than those used in radiation treatments, so if there is any increase in risk, it is likely to be 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. A weakened immune system can be congenital (present at birth), or it can be caused by treatments for other cancers, treatment to prevent rejection of transplanted organs, or diseases such as AIDS.
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. But any increase in brain tumour risk from cancer treatment is small compared to the risk of not having the treatment for the original cancer.
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.
Most people with brain tumors do not have a family history, but in rare cases (5%) brain cancers run in families. In general, patients with familial cancer syndromes tend to have many tumors that first occur when they are young. Some of these familial cancer syndromes and the associated brain tumours include Neurofibromatosis type 1 & type 2 (schwannomas, meningiomas, gliomas, neurofibromas, ependymomas) Tuberous sclerosis(subependymal giant cell astrocytomas) Von Hippel-Lindau disease (hemangioblastomas) Li-Fraumeni syndrome (gliomas), Gorlin syndrome (basal cell nevus syndrome),Turcot syndrome, Cowden syndrome
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 tumors..
Exposure to aspartame(a sugar substitute) and infection with certain viruses(Epstein Barr virus, human Cytomegalovirus, polyoma virus) have been suggested as possible risk factors, but research on these continues..
Factors with uncertain, controversial, or unproven effects on brain tumor risk:
Cell phone use
This has been the subject of a great deal of debate in recent years. 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 inside cells. The phones, whose antennae are built-in and therefore are placed close to the head when being used, might somehow raise the risk of brain tumors.
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 into the long-term, heavy use of mobile phones needs to be conducted.
Studies to date provide no indication that environmental exposure to RF fields, such as from base stations, increases the risk of cancer or any other disease.
There are some inconclusive studies that Cell phone users had a mild increased risk of malignant gliomas. ,and acoustic neuromas.
Tumors are more likely to occur on the side of the head that the cell handset is used.
One hour of cell phone use per day may increases tumor risk after ten years or more. The same is true of any possible higher risks in children, who are increasingly using cell phones.
Cell phone technology also continues to change, and it’s not clear how this might affect any risk.
All these needs to be proved with further research and studies.
So as of now recommendations to reduce such risks can be by
Using an earpiece such that the hand set is away from the head
Avoid continuous use for more than 15- 20 minutes
More use of texting
Do not use telephone in a car without an external antenna.
Avoid using cell phones in fast moving objects like vehicles, lifts etc
Encourage people using phone continuously like receptionists, call centre workers etc to use land phones
Body size and Exercise
Overweight may have a slightly higher risk of meningioma than in smaller people. But being overweight doesn’t seem to affect glioma risk. Children weighing 4kg or more at birth have a small increased risk of some brain tumour types compared with lighter babies.Taller people might have an increased risk but the evidence on this is still mixed. Studies that look at food and drink in relation to brain tumour risk are not felt to be reliable. This is because brain tumours are relatively rare and measuring diet accurately is very difficult. People who are very physically active might reduce their brain tumour risk but the evidence is mixed.
Diet, Smoking and Alcohol
Some studies of diet and vitamin supplementation seem to indicate that dietary N-nitroso compounds may raise the risk of both childhood and adult brain tumors. Dietary N-nitroso compounds are formed in the body from nitrites or nitrates found in some cured meats, cigarette smoke, and cosmetics. It’s not yet clear whether smoking affects brain tumour risk. But some studies have shown increased risks for some types of brain tumour. Drinking alcohol doesn’t seem to affect risk.
Headache occurring in later onset of life and gradually increasing in intensity. There can be a constant aching pain without any painfree period inbetween. Usually Headache maximum in the morning and the victim wakes up with severe headache
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.
New onset seizures with can be focal seizures ( More significant) involving only part of the body or it can be generalized seizures.
Weakness or numbness- progressively increasing and can involve only one limb or one side of the body.
Visual problems especially when it involves the optic Nerve( nerve of vision) or pituitary gland.
Cognitive problems occurring suddenly like memory problems, behavioral changes, language problems , confusions etc
Difficulty in speech when tumour involves the speech area
Gait disturbances, imbalance ,in coordination or weakness of facial muscles
Rapid personality changes
Tumours like Meningiomas, Certain Gliomas, Pituitary adenomas, Nerve sheath tumors, germ cell tumours, haemangioblastomas, cavernomas, and certain Lymphomas are curable.
Survival rates in brain tumors depend on the
- Type of tumor, size, area involved and early detection
- Age and health of the patient,
- Extent of surgical tumor removal.
The primary and most desired course of action is surgical removal (resection) via craniotomy. Minimally invasive techniques is the trend in neurosurgery. Endoscopic surgeries are also being done. With the availability of ultramodern operating microscopes, neuronavigation systems, Cavitron ultra sonic aspirator, endoscopes and other sophisticated instruments along with better understanding of surgical techniques, the safety and success rate for brain tumour surgery has dramatically improved.
Radiotherapy is the most commonly used treatment for brain tumors. 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. Types of stereotactic radiosurgery, include Gamma knife, linear accelerator and Cyberknife.
Chemotherapy: is a treatment option for cancer, and can improve survival in 20% brain cancers.
Role of pharmacological therapy is limited except for anti epileptics(controlling fits) and steroids(reduce brain oedema)
Extensive research and studies are going on for better understanding of the behavior of different brain tumours and more and more treatment modalities are being tried to fight this dreaded disease. Immunotherapy/ biological response modifier (BRM) therapy, Oncolytic virus therapy. Targeted therapy of faulty genes or proteins, Gene therapy. Hormonal therapy, photodynamic therapy and Electric field therapy are some of the treatment modalities that may bring hope in the future.