A tumour is an abnormal mass of tissue. It is formed when there is uncontrolled growth and division of the cells in these tissues. Tumours are also called neoplasms. They may be
- non-cancerous (benign tumours) or
- cancerous (malignant tumours).
Brain tumours that develop in the brain are called primary tumours.
Brain tumours that have spread to the brain from another region in the body are secondary tumours. The process of tumour cells spreading to different parts from the cells of their origin is called metastasis. Tumour cells may spread through the circulating blood.
Tumours are generally graded to denote their characteristics and to help determine the appropriate treatment. Usually, the grades given to any tumour are 1,2,3 and 4.
They can be grade 1 or 2 tumours which show slow growth and have the least malignant properties, or they can be progressively classified as grade 3 or 4, which means they are growing fast and spreading rapidly.
Benign tumours can grow large but normally do not spread into nearby tissues or organs, or to other parts of the body. They usually grow at a slow pace and are classified as grade 1 or 2. Benign brain tumours are also classified by the type of cells and tissues which are affected. For example:
- Meningiomas affect the layers or the membranes that form the covers over the brain.
- Pituitary adenomas affect the small pituitary gland at the base of the brain.
- Hemangioblastomas are tumours of the blood vessels in the brain.
Strangely, some tumours show no symptoms. They are discovered incidentally while the patient is undergoing treatment for some other condition. Some of the common symptoms are:
- Persistent headaches and episodes of fits (epileptic seizures)
- Continuous sickness and a feeling of drowsiness
- Behavioural changes, and personality disorders
- Vision and speech difficulties and partial paralysis of the face and limbs.
Although the cause of most benign brain tumours is not certain, there are certain risk factors.
Age: Most patients are above 50 years of age,
History: There is almost always a family history of brain tumours.
Genetic disorders and some syndromes: Some genetic conditions may predispose individuals to develop certain benign tumours.
Radiation: If a patient has previously undergone radiotherapy, there is a chance of tumour formation.
The neurologist will start by testing basic functions of the brain, such as:
- Body reflexes,
- hand-eye coordination,
- balance and memory.
Further tests as follows could be carried out to detect the presence of a tumour:
CT scan and MRIs help to visualized detailed images of the brain.
In brain angiography, a catheter is inserted into an artery and guided to the desired region. With the help of contrast dyes, X- rays or digital images provide accurate information about abnormal tissues, and blood supply to tumours.
An Electro Encephalogram (EEG) is used to record the patient’s brain activity and confirm the cause of epileptic fits.
Biopsy: If a tumour is detected, a small sample of the tissue is surgically removed, and sent for microscopic evaluation. This procedure is called a biopsy. Doctors can then determine if the growth is benign or malignant and start appropriate treatment.
Benign brain tumours have well defined borders and are usually not present in deep tissues.
- Surgical removal of a benign brain tumour will be attempted if it can be safely done, without damage to the brain. The patient is kept awake for a part of the surgery to ensure that there is no inadvertent damage, especially to speech.
- If the tumour has been removed completely, there is usually no recurrence. But even if tiny bits of the abnormal tissue are left behind, there is a risk of the tumour growing back.
- In such a case, radiotherapy may be started.
- If the location of the tumour makes surgery risky, chemotherapy and radiation therapy may be used to shrink the tumour.
Although benign tumours are not aggressive in growth, they may be serious and sometimes even fatal.
Malignant tumours usually invade nearby tissues and the cancerous cells also tend to be transported through the blood to distant parts of the body. They are also referred to as metastatic tumours. They are usually classified as grade 3 or 4. Most malignant brain tumours are secondary tumours, which means they had originated somewhere else in the body.
The location of the tumour in the brain and its size greatly influence the symptoms and signs.
- Headaches which are worse during the mornings are among the earliest symptoms
- Epileptic fits or seizures may occur in a person with no history of fits
- Speech or vision problems become more obvious
- There is a constant feeling of sickness and vomiting without nausea
- Memory problems and changes in personality may be observed
- Difficulty in maintaining balance and walking is experienced
- Numbness and tingling sensation in one side of the face or other body parts
It is generally believed that the risk factors for benign and malignant brain tumours are the same. Environmental toxins, exposure to radiation and genetics are some known causes of malignant tumours.
Secondary brain tumours are usually seen in patients with a history of cancer in some other organ.
Some common cancers that can spread to the brain are breast and lung cancer; and kidney and colon cancer.
Diagnosis starts with a physical exam and thorough history-taking.
Neurological assessments are carried out to determine if any bodily functions are impaired.
Biopsy, CT, MRI and PET scans, cerebral angiography/ Brain angiogram can be done to determine the location of the tumour and the blood supply to it.
CSF/Spinal tap: Fluid from around the spine is drawn out and examined to determine if tumour cells or tumour markers are present in the cerebrospinal fluid.
The treatment of malignant tumours depends on the classification and the location of the tumour in the brain. The aim of treatment is to remove the tumour completely to prevent recurrence.
Surgery: Usually surgery is attempted when there are at least two areas of cancerous cells and the tumours are large and are causing serious symptoms
Radiotherapy may be carried out before surgery and almost always after surgery to kill the remaining cancer cells.
Chemotherapy is also given after surgery, either to eliminate cancerous cells or to relieve symptoms if surgery is not feasible.