Brain tumour

Description

Brain tumours are the result of the overgrowth of abnormal (mutated) cells from tissue within the skull (cranium). The  presenting symptoms are the result of the expanding tumour causing a rise in intra-cranial pressure and distortion of the normal brain tissue.

• Some of the symptoms caused by a brain tumour can include: seizures, weakness, headache, confusion and change in behaviour.
• A tumour, whether it's in your brain or elsewhere, is a mass of often rapidly grrowing abnormal cells.
• Brain tumours can be benign or malignant.

The brain controls vital functions such as memory and learning, the senses (hearing, sight, smell, taste, and touch), and emotion. It also controls other parts of the body, including muscles, organs, and blood vessels. The tumours as they grow, compress the normal brain tissue and in so doing affect the function of that particlar part of the brain. As a result, brain tumours, both benign and malignant, can have a major impact on the normal function of the patient.

The prognosis of brain tumours is dependent on the type of tumour (benign or malignant), the grade of the tumour (this describes its rate of growth) and the position of the tumour in the brain (this determines whether it is operable and how much can be safely resected by the neurosurgeon). The intervention that offers the best chances of a good outcome remains surgical removal of as much of the tumour as possible. Despite this, and along with  recent advances in radiotherapy and chemotherapy, the majority of malignant brain tumours have a poor prognosis. 

Fortunately brain tumours are relatively rare, but in children under 15 it is the second leading cause of cancer deaths.

The diagnosis of brain tumours has been increasing in recent years.  Experts are not yet sure whether this is due to better detection methods or an actual increase in the number of tumours. The link of low-dose ionising radiaiton to the head, mainly from cell phones and cordless phones has raised concerns of a possible link to this increase. In early 2011 a directive was issued by by a group of concerned doctors in Sweden who had done extensive research into this. They suggest that everyone, young children in particular, should limit their use of cell phones to short calls, and preferably use text messaging, handsfree or speaker phone settings. They feel that there is compelling evidence linking cell phone use to damage to brain tissue, leading to an increased risk of tumours as well as other brain cell damage.

Tumour types

Brain tumours fall into two main categories:

• Primary — These tumours begin in brain tissue. About 25 percent of brain tumours are primary. Primary brain tumours can be benign or malignant. About 40% percent are benign and can be treated successfully.

Although the causes of primary brain tumours are unknown, about five percent are believed to be related to hereditary factors. Primary tumours are more common in children under age 15 and in older adults. Within this category, there are many types of  tumours, depending on which kind of cell in the brain initially became malignant. The brain tissue consists of two main types of cells – neurones and glial cells. Most malinant tumours arise from the glial cells and are called gliomas or astrocytomas. There are also blood vessels and the meninges which cover the brain and spinal cord and tumours or can arise from the cells of these structures.

• Metastatic - Metastatic or secondary brain tumours are tumours resulting from a cancer that started elsewhere in the body and then spread (metastasized) to the brain via the blood stream. Melanoma, lung, colon and breast  cancers are the most common cancers that may  spread to the brain. About 75 percent of brain tumours are metastatic. 

Symptoms

Brain tumours, whether benign or malignant, can cause a variety of problems depending on their location inside the confined space of the head. As the brain is surrounded by a rigid skull, the increase in size of the tumour causes a resultant increase in intra-cranial pressure. The signs and symptoms of a brain tumour are  dependent on the tumour type, rate of growth and location of the lesion.

Signs and symptoms can include:

• Seizures
• Weakness or change in sensation
• Headaches
• Change in behaviour

The main symptom in children is headache or unsteadiness on walking or seizures. Adults will mostly have seizures, weakness and change in behaviour, with or without headache.

When a headache can spell trouble

They can also signal temporal arteritis, an inflammation that affects arteries in the scalp, brain and eyes. Temporal arthritis can lead to blindness or stroke if left untreated: note that it has nothing to do with brain tumours.

So how do you know when to seek medical care for a headache? Talk to your doctor about new headache pain or any headache that concerns you. Even if you have a history of headaches, see your doctor if the pattern changes, or they feel different. Most importantly, be aware that headache alone is unlikely to be associated with a brain tumour: the main reason to see a doctor for your headache is to receive effective treatment for your headaches so that they become less troublesome.

In addition, see your doctor or go to the emergency room immediately if you have any of these warning signs:

• Sudden, severe headache pain, often like a "thunderclap"
• Headache with fever, stiff neck, rash, mental confusion, seizures, double vision, weakness, numbness, vomiting, or difficulty speaking
• Chronic, progressive headache that worsens after coughing, exertion, straining or a sudden movement

Diagnosis

Diagnosing a brain tumour usually involves several steps. Your physician may perform a neurological examination, which includes checking your vision, hearing, balance, coordination and reflexes, among other things.

You may also have a computed tomography (CT) scan or magnetic resonance image (MRI) scan. A CT scan is a diagnostic test that uses computers and X-rays to create pictures of the body. An MRI scan is similar, but uses magnetic waves instead of X-rays.

Often surgery is required to determine whether a brain tumour exists and what type of tumour it is. A small sample of tumour tissue may be surgically removed and examined under a microscope. This is called a biopsy. Sometimes a biopsy is done by making a small hole in the skull and using a needle to extract a sample of the tumour.

Once the brain tumour is detected, additional tests will be performed to determine the type of tumour. If a biopsy specimen is taken, the tumour cells will be examined carefully under a microscope to see how different they appear from normal cells. Cells from higher-grade, more abnormal-looking tumours usually grow faster and are more malignant than cells from lower-grade tumours. The doctor needs to know the type and grade of tumour in order to plan treatment.

Brain tumours are grouped according to their location within the brain and the appearance and behaviour of the tumour tissue.

The following groupings are used:

Infratentorial tumours are those that occur in the lower part of the brain. Tumours found in this region include:

• Medulloblastoma: Occurs in children and young adults and tends to spread down to the spinal canal and spinal cord.
• Cerebellar astrocytoma: A benign tumour occurring in young adults and children. It is frequently curable by surgery only.
• Brain stem glioma: Mostly malignant tumours of the lower central part of the brain, infiltrating the area of the brain responsible for such vital functions as breathing, blood pressure, body temperature control and so on.

Supratentorial tumours are those that occur in the upper part of the brain. Common supratentorial tumours include:

• Cerebral astrocytoma and oligodendroglioma: The prognosis of these tumours depends on the exact location of the tumour (how accessible it is for surgery) and the grade of the tumour (how malignant the cells look under the microscope). The most malignant variant is called Glioblastoma Multiformae.
• Craniopharyngioma: These tumours generally occur just above the pituitary gland. Located at the bottom of the brain, the pituitary gland is about the size of a pea and controls many vital functions. Craniopharyngiomas do not spread, but may interfere with important structures near them, causing serious problems.
• Central nervous system germ cell tumour: Germ cell tumours arise from the sex cells found in the brain. There are different types of germ cell tumours, including germinomas, embryonal cell carcinomas, choriocarcinomas, and teratomas. These tumours usually occur in the centre of the brain, and can spread to other parts of the brain and spinal cord.
• Supratentorial primitive neuroectodermal and pineal tumours: Very malignant tumours similar to medulloblastoma originating from primitive brain cells. They tend to spread along the spinal canal to other structures of the brain and the spinal cord.
• Visual pathway and hypothalamic glioma: These are tumours arising from the optic nerves (nerve that conduct the image from the eyes to the brain). They usually occur in children and can cause blindness.
• Meningioma: Usually benign tumours arising from the envelope of the brain. These tumours rarely infiltrate the brain; rather they compress the underlying brain structures.
• Pituitary gland tumours: These are generally benign growths of cells from the pituitary gland. The pituitary gland (or hypophysis) secretes hormones that are responsible for functions of other glands such as:

             - Thyroid gland (energy level)

             - Adrenal glands (general well being and body salt balance)

             - Testes and ovaries

             -  Lactating glands

The major symptoms, besides headache, are accelerated or stunted growth, lack of energy, metabolic disturbances, irregular menstrual periods among many others. As the optic nerves are very close to the gland, tumours of the pituitary gland can cause blindness as a result of nerve compression.

Recurrent brain tumour

Recurrent disease means that the cancer has come back (recurred) after it has been treated. It may recur in its original location, in another part of the central nervous system, or systemically (throughout the body).

Treatment

Treatment depends on the type of brain tumour. The three main treatment methods are: Surgery, Radiation and Chemotherapy.

• Surgery - This is the mainstay of brain tumour treatment. It involves removing as much of the tumour as possible, while trying to minimize damage to the healthy tissue. The aim could be either complete removal of the tumour (complete resection) or removing only a part of it in order to facilitate the radiotherapy thereafter (debulking). Complete resection of malignant tumours is usually not possible.
• Radiation - By careful aiming and regulation of the dose, high-energy radiation can be used to destroy cancer cells. The X-rays are either produced by a special machine outside the body and are directed to the place of the tumour in the brain (this is called External Beam Radiotherapy), or are produced by radioactive material that is inserted surgically into the tumour (this is named Brachytherapy). Unfortunately, radiation of the whole brain, which is often given in the case of malignant tumours, has side effects such as cell damage with change in personality and loss of intelect in some cases.
• Chemotherapy - Drugs are used to kill cancer cells and shrink tumours. Chemotherapy may be taken by pill, or it may be put into the body by inserting a needle into a vein or muscle. Chemotherapy is called a systemic treatment because the drugs enter the bloodstream and can kill cancer cells throughout the body. Although chemotherapy is highly effective in treating some cancers, it is less successful in treating brain tumours. However it has a very well established place in palliative settings (when the major objective is not a cure, but the alleviation of symptoms). Chemotherapy is also very important in treating of some childhood brain tumours. As always with chemotherapy, patients need to carefully examine the risks and benefits of treatment: in the event that the prognosis is grave, chemotherapy may adversely affect quality of life at a time and require hospitalization when patients need to make the most of their time with their families and loved ones.

Many brain tumours are treated with a combination of therapies.

Novel and experimental treatments
New technology is evolving and helping to make the treatment of tumours more precise. One of the most important advances is stereotactic localisation. This technique utilises a three-dimensional MRI scan to map the tumour's exact location.

New techniques using lasers and ultrasound also make actual removal of the tumour more precise, reducing the risk that cancer cells will be left behind and that healthy tissue be harmed.

Some of the most intriguing new methods in brain tumour treatment involve the use of radiation. A treatment that precisely focuses radiation beams to the tumour is called stereotactic radiosurgery. No scalpels are involved. Stereotactic radiosurgery delivers radiation beams in the exact size and shape of the tumour.

New ways to deliver cancer-fighting drugs to the brain tumours are also being studied. Chemo "wafers" implanted in a tumour during surgery have shown promise for some types of cancer. The wafers are biodegradable chips containing cancer-fighting drugs.

Experimental treatments under investigation include gene therapy, drugs that cut off a tumour's blood supply and agents that may be able to interrupt tumour growth or seek out and kill cancer cells.

Many of these are being tested in clinical research trials. If you have a brain tumour, participating in a clinical trial can help you have access to the newest experimental treatments and, at the same time, play an important role in helping to define the role of these new treatments.

Summary

Newly appeared headache is a symptom deserving careful investigation; this however does not mean that all headaches are symptomatic of brain tumours, there are thousands of reasons for headache, most of which are not tumour related.

Even when "cure" is not possible, due to the location or type of the tumour, modern medicine has many things to offer in terms of alleviating the symptoms, preserving functions such as vision and prolonging the life. Patients with malignant brain tumours need to carefully weigh up their options, and should routinely obtain second opinions about treatment. Chemotherapy and radiotherapy may be of benefit in terms of extending duration of survival, but may adversely affect quality of life.

Previously reviewed by Dr J. Carr, FCP(SA) Neurology, MSc(Med). Reviewed by Dr David Eedes, Oncologist, March 2011.

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