Questions
and Answers
1. What is a
brain tumour?
A brain tumour is
an abnormal mass of tissue in which the cells grow and multiply without
restraint, apparently unregulated by the mechanisms that control normal cells.
One factor that distinguishes brain tumours from other tumours is that they
arise in the skull, an organ encased by bone, and there is very little room for
expansion with the skull. They are also among the few types of tumours that
generally do not tend to metastasise or spread to other parts of the body.
Whereas certain brain tumours occur almost exclusively during childhood and
adolescence, others are predominantly tumours of adult life. The patient's age
appears to correlate with the site where some tumours develop in the brain.
Although most primary tumours attack member of both sexes with equal frequency,
some, such as meningiomas, occur more frequently in women, while others, such
as medulloblastomas, more commonly afflict boys ond young men. The prognosis
for patients with a brain tumour is as individual as the patients themselves.
Your doctors will help you understand the possible consequences of your
specific tumour.
2. What is the
difference between a primary brain tumour and a metastatic (secondary) brain
tumour?
Primary brain
tumours arise from the brain itself. The tumour cells do not travel to the
brain from other parts of the body and, in most cases, primary brain tumour
cells do not travel to other parts of the body either. The most common
exception to this rule is the primary brain tumour of childhood called
medulloblastoma, which can spread to the lymph nodes, bone marrow, lungs or
other parts of the body. But even in this case, it is unusual for
mebulloblastoma to spread outside the nervous system.
Pathologists
classify primary brain tumours into two groups: the gliomas, composed of
"glial" cells that invade the neural tissue surrounding them; and the
nonglial tumours, which are not composed of glial cells and compress, rather
than invade, the neighbouring brain as they grow. Metastatic (secondary) brain
tumours will have spread to the brain from another part of the body. They most
often metastasise from tumours of the lung or breast but almost any tumour can
spread to the brain. They arise when abnormal cells that developed elsewhere in
the body are carried to the brain by the blood flow. Metastatic tumours are the
most common form of brain tumour, considerably outnumbering primary brain
tumours by about 100,000 new cases each yeor.
3. What is the
difference between a benign brain tumour and a malignant brain tumour?
Benign brain
tumours do exist, and often can be cured with surgery alone. Some primary brain
tumours are called benign because their rate of growth is so slow that many
yeors may pass before the tumour grows large enough to compress functional
areas of the brain, causing symptoms that require treatment. Others are
considered benign because - once the tumour is diagnosed and treated - in many
cases, the patient will be cured and live a normal life span and in many
others, the tumour will not grow back for many years or even decades. We use
the term benign with caution, however. Even a benign brain tumour may cause
intolerable symptoms or may not be controllable because of its particular
location in the brain.
A tumour in the
brain stem or the spinal cord, for example, is often impossible to remove with
surgery. In those particular locations even a small amount of tumour growth can
compress and cause very serious damage to brain or spinal structures that
control functions critical to life. While such a tumour may be called
"benign" because of its slow growth, the situation is far from
benign. We are not certain why, but some benign brain tumours may change over
time to become malignant. The meningioma, for instance, is one type of primary
brain tumour that can be cured, either with surgery alone or sometimes with
surgery and radiation therapy. In such cases, meningioma is considered a benign
tumour. But in rare cases, even a meningioma may have invasive features, which
the pathologist can see in the tumourŐs cells under the microscope and which
suggest that the tumour may behave more aggressively than usual. In such a
case, the meningioma may not be curable. It may continue to grow despite
surgery, irradiation.