What is a Brain Tumour?
A brain tumour is the growth of abnormal cells in the brain. When most normal cells grow old or get damaged, they die, and new cells take their place. Sometimes, this process goes wrong. New cells form when the body doesn't need them, and old or damaged cells don't die as they should. The build-up of extra cells often forms a mass of tissue called a growth or tumour.
Brain tumours are classified as either benign (non-cancerous) or malignant (cancerous). Brain tumours are also classified as either primary or metastatic. When a brain tumour originates in the brain it is referred to as a primary brain tumour. Metastatic brain tumours begin as cancer elsewhere in the body and then spread to the brain.
Tumour Grades and Types
Primary brain tumours, tumours that originate in the brain, can be benign or malignant:
Benign brain tumours do not contain cancer cells:
- Usually, benign tumours can be removed, and they seldom grow back.
- Benign brain tumours usually have an obvious border or edge. Cells from benign tumours rarely invade tissues around them. They don't spread to other parts of the body. However, benign tumours can press on sensitive areas of the brain and cause serious health problems.
- Unlike benign tumours in most other parts of the body, benign brain tumours are sometimes life threatening.
- Benign brain tumours may become malignant.
Malignant brain tumours (also called brain cancer) contain cancer cells:
- Malignant brain tumours are generally more serious and often are a threat to life.
- They are likely to grow rapidly and crowd or invade the nearby healthy brain tissue.
- Cancer cells may break away from malignant brain tumours and spread to other parts of the brain or to the spinal cord. They rarely spread to other parts of the body.
Doctors group brain tumours by grade. The grade of a tumour refers to the way the cells look under a microscope:
- Grade I: The tissue is benign. The cells look nearly like normal brain cells, and they grow slowly.
- Grade II: The tissue is malignant. The cells look less like normal cells than do the cells in a Grade I tumour.
- Grade III: The malignant tissue has cells that look very different from normal cells. The abnormal cells are actively growing (anaplastic).
- Grade IV: The malignant tissue has cells that look most abnormal and tend to grow quickly.
Types of Primary Brain Tumours
There are many types of primary brain tumours. Primary brain tumours are named according to the type of cells or the part of the brain in which they begin. For example, most primary brain tumours begin in glial cells. This type of tumour is called a glioma.
Among adults, the most common types are:
- Astrocytoma: The tumour arises from star-shaped glial cells called astrocytes. It can be any grade. In adults, an astrocytoma most often arises in the cerebrum.
- Meningioma: The tumour arises in the meninges. It can be grade I, II, or III. It's usually benign (grade I) and grows slowly.
- Oligodendroglioma: The tumour arises from cells that make the fatty substance that covers and protects nerves. It usually occurs in the cerebrum. It's most common in middle-aged adults. It can be grade II or III.
Among children, the most common types are:
- Medulloblastoma: The tumour usually arises in the cerebellum. It's sometimes called a primitive neuroectodermal tumour. It is grade IV.
- Grade I or II astrocytoma: In children, this low-grade tumour occurs anywhere in the brain. The most common astrocytoma among children is juvenile pilocytic astrocytoma. It's grade I.
- Ependymoma: The tumour arises from cells that line the ventricles or the central canal of the spinal cord. It's most commonly found in children and young adults. It can be grade I, II, or III.
- Brain stem glioma: The tumour occurs in the lowest part of the brain. It can be a low-grade or high-grade tumour. The most common type is diffuse intrinsic pontine glioma.
Symptoms of Brain Tumour
The symptoms of a brain tumour depend on tumour size, type, and location. Symptoms may be caused when a tumour presses on a nerve or harms a part of the brain. Also, they may be caused when a tumour blocks the fluid that flows through and around the brain, or when the brain swells because of the build-up of fluid. These are the most common symptoms of brain tumours:
- Problems with memory Problems balancing or walking
- Headaches (usually worse in the morning)
- Muscle jerking or twitching (seizures or convulsions)
- Nausea and vomiting Changes in speech, vision, or hearing
- Numbness or tingling in the arms or legs
- Changes in mood, personality, or ability to concentrate
Most often, these symptoms are not due to a brain tumour. Another health problem could cause them. If you have any of these symptoms, you should tell your doctor so that problems can be diagnosed and treated.
Risk Factors for Brain Tumours
When you're told that you have a brain tumour, it's natural to wonder what may have caused your disease. But no one knows the exact causes of brain tumours. Doctors seldom know why one person develops a brain tumour and another doesn't. Researchers are studying whether people with certain risk factors are more likely than others to develop a brain tumour. A risk factor is something that may increase the chance of getting a disease.
Studies have found the following risk factors for brain tumours:
- Ionizing radiation: Ionizing radiation from high dose x-rays (such as radiation therapy from a large machine aimed at the head) and other sources can cause cell damage that leads to a tumour.
- Family history: It is rare for brain tumours to run in a family. Only a very small number of families have several members with brain tumours.
If you have symptoms that suggest a brain tumour, your doctor will give you a physical exam and ask about your personal and family health history. You may have one or more of the following tests.
- Neurologic Exam
- CT Scan
- Spinal Tap
Neurologic Exam: Your doctor checks your vision, hearing, alertness, muscle strength, coordination, and reflexes. Your doctor also examines your eyes to look for swelling caused by a tumour pressing on the nerve that connects the eye and the brain.
MRI: A large machine with a strong magnet linked to a computer is used to make detailed pictures of areas inside your head. Sometimes a special dye (contrast material) is injected into a blood vessel in your arm or hand to help show differences in the tissues of the brain. The pictures can show abnormal areas, such as a tumour.
CT Scan: An x-ray machine linked to a computer takes a series of detailed pictures of your head. You may receive contrast material by injection into a blood vessel in your arm or hand. The contrast material makes abnormal areas easier to see.
Angiogram: Dye injected into the bloodstream makes blood vessels in the brain show up on an x-ray. If a tumour is present, the x-ray may show the tumour or blood vessels that are feeding into the tumour.
Spinal Tap: Your doctor may remove a sample of cerebrospinal fluid (the fluid that fills the spaces in and around the brain and spinal cord).
Biopsy: The removal of tissue to look for tumour cells is called a biopsy. A pathologist looks at the cells under a microscope to check for abnormal cells. A biopsy can show cancer, tissue changes that may lead to cancer, and other conditions. A biopsy is the only sure way to diagnose a brain tumour, learn what grade it is, and plan treatment.
People with brain tumours have several treatment options. The options are surgery, radiation therapy, and chemotherapy. Many people get a combination of treatments. The choice of treatment depends mainly on the following:
- The type and grade of brain tumour
- Its location in the brain
- Its size
- Your age and general health
You and your health care team can work together to develop a treatment plan that meets your medical and personal needs.
Chemotherapy, the use of drugs to kill cancer cells, is sometimes used to treat brain tumours. Drugs may be given in the following ways:
- By mouth or vein (intravenous): Chemotherapy may be given during and after radiation therapy. The drugs enter the bloodstream and travel throughout the body. They may be given in an outpatient part of the hospital, at the doctor's office, or at home. Rarely, you may need to stay in the hospital. The side effects of chemotherapy depend mainly on which drugs are given and how much. Common side effects include nausea and vomiting, loss of appetite, headache, fever and chills, and weakness. If the drugs lower the levels of healthy blood cells, you're more likely to get infections, bruise or bleed easily, and feel very weak and tired. Your health care team will check for low levels of blood cells. Some side effects may be relieved with medicine.
- In wafers that are put into the brain: For some adults with high-grade glioma, the surgeon implants several wafers into the brain. Each wafer is about the size of a dime. Over several weeks, the wafers dissolve, releasing the drug into the brain. The drug kills cancer cells. It may help prevent the tumour from returning in the brain after surgery to remove the tumour.
Radiation therapy kills brain tumour cells with high-energy x-rays, gamma rays, or protons. Radiation therapy usually follows surgery. The radiation kills tumour cells that may remain in the area. Sometimes, people who can't have surgery have radiation therapy instead.
Doctors use external and internal types of radiation therapy to treat brain tumours:
- External radiation therapy: You'll go to a hospital or clinic for treatment. A large machine outside the body aims beams of radiation at the head. Because cancer cells may invade normal tissue around a tumour, the radiation may be aimed at the tumour and nearby brain tissue, or at the entire brain. Treatments are usually 5 days a week for several weeks. A typical visit lasts less than an hour, and each treatment takes only a few minutes.
- Internal radiation therapy (implant radiation therapy or brachytherapy): Internal radiation isn't commonly used for treating brain tumours and is under study. The radiation comes from radioactive material usually contained in very small implants called seeds. The seeds are placed inside the brain and give off radiation for months. They don't need to be removed once the radiation is gone. Some people have no or few side effects after treatment. Rarely, people may have nausea for several hours after external radiation therapy. Also, external radiation therapy commonly causes hair loss from the part of the head that was treated. Hair usually grows back within a few months. Radiation therapy also may make the skin on the scalp and ears red, dry, and tender. The health care team can suggest ways to relieve these problems.
Surgery is the usual first treatment for most brain tumours. However, sometimes surgery isn't possible. If the tumour is in the brain stem or certain other areas, the surgeon may not be able to remove the tumour without harming normal brain tissue. People who can't have surgery usually receive radiation therapy or other treatment. Tumour location, size and type are considered when deciding the type of surgery to perform. Surgery to remove a lesion in the brain is called a Craniotomy. This is “open” brain surgery requiring removal of part of the skull bone to access the brain tissues. Minimally invasive brain surgery may also be an option depending on your particular circumstances. Minimally invasive surgery is performed with an endoscope through the nose (endonasal) or through a tiny incision above the eye in order to remove the brain tumour. The endoscope is a special lighted instrument that sends images back to a computer for the surgeon to view internal structures and enables the surgeon to use tiny instruments within the endoscope to remove the tumour. Your healthcare team will discuss all options with you prior to surgery. This learning module instructs on Craniotomy or “open” brain surgery.
A Craniotomy is performed in the hospital operating room with the patient under general anaesthesia. The scalp is shaved where the incision will be made over the skull. You may be awake when the surgeon removes part or the entire brain tumour.
The surgeon removes as much tumour as possible. You may be asked to move a leg, count, say the alphabet, or tell a story. Your ability to follow these commands helps the surgeon protect important parts of the brain.
The surgeon makes an incision in your scalp over part of the skull and the skin is pulled back. A drill is then used to place holes in the bone at various points. The surgeon then uses a special type of saw to cut the bone between the holes to remove a piece of bone from the skull. The brain tumour is located through the use of imaging studies and the tumour is removed. Your surgeon will remove as much of the tumour as is safely possible without harming surrounding structures. After the tumour is removed, a drain is placed, and the surgeon covers the opening in the skull with the piece of bone or with a piece of metal or fabric. The drain removes any excess blood from the surgery. The surgeon then closes the incision in the scalp.
After surgery your surgeon will give you guidelines to follow depending on the type of repair performed and the surgeon’s preference. Common Post-operative guidelines following brain tumour surgery include:
- You will be transferred to ICU after surgery for close monitoring.
- You will probably stay in the hospital a few days if no complications occur.
- You may hear a clicking noise at the incision site on the skull. This is a normal part of the bone healing and may take 6-12 months to fully heal.
- Headaches are common after brain surgery and can continue for a long time. Your doctor can prescribe medications for pain relief.
- Keep the incisions clean and dry. You may shower once the dressings are removed unless otherwise directed by your surgeon.
- You will be given specific instructions regarding activity and rehabilitation.
- Eating a healthy diet and not smoking will promote healing.
- It is important to keep all your postoperative appointments with your surgeon to ensure a good outcome.
Risks and Complications
As with any major surgery there are potential risks involved. The decision to proceed with the surgery is made because the advantages of surgery outweigh the potential disadvantages. It is important that you are informed of these risks before the surgery takes place.
Complications can be medical (general) or specific to brain surgery. Medical complications include those of the anaesthetic and your general wellbeing. Almost any medical condition can occur, so this list is not complete. Complications include:
- Allergic reaction to medications
- Blood loss requiring transfusion with its low risk of disease transmission
- Heart attack, strokes, kidney failure, pneumonia, bladder infections
- Complications from nerve blocks such as infection or nerve damage
- Serious medical problems can lead to ongoing health concerns, prolonged hospitalization, or rarely death.
Complications are rare after brain tumour surgery, but unexpected events can follow any operation. Factors influencing the development of complications include the location, type and size of the tumour. Your surgeon feels that you should be aware of complications that may take place so that your decision to proceed with this operation is taken with all relevant information available to you.
Specific complications of Brain Tumour surgery can include:
- Brain damage
- Brain swelling
Risk factors that can negatively affect adequate healing after surgery include:
- Poor nutrition
- Chronic illnesses
- Steroid use
- Age (Over 60)