Brain Tumors
What is a Brain Tumor?
A brain tumor 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 does not need them, and old or damaged cells do not die as they should. The buildup of extra cells often forms a mass of tissue called a growth or tumor.
Brain tumors are classified as either benign (non-cancerous) or malignant (cancerous). Brain tumors are also classified as either primary or metastatic. When a brain tumor originates in the brain it is referred to as a primary brain tumor. Metastatic brain tumors begin as cancer elsewhere in the body and then spread to the brain.
Tumor Grades and Types
Primary brain tumors, tumors that originate in the brain, can be benign or malignant:
Benign brain tumors do not contain cancer cells:
- Usually, benign tumors can be removed, and they seldom grow back.
- Benign brain tumors usually have an obvious border or edge. Cells from benign tumors rarely invade tissues around them. They do not spread to other parts of the body. However, benign tumors can press on sensitive areas of the brain and cause serious health problems.
- Unlike benign tumors in most other parts of the body, benign brain tumors are sometimes life-threatening.
- Benign brain tumors may become malignant.
Malignant brain tumors (also called brain cancer) contain cancer cells:
- Malignant brain tumors 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 tumors and spread to other parts of the brain or to the spinal cord. They rarely spread to other parts of the body.
Tumor Grades
Doctors group brain tumors by grade. The grade of a tumor 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 tumor.
- 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 Tumors
There are many types of primary brain tumors. Primary brain tumors are named according to the type of cells or the part of the brain in which they begin. For example, most primary brain tumors begin in glial cells. This type of tumor is called a glioma.
Among adults, the most common types are:
- Astrocytoma: The tumor 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 tumor arises in the meninges. It can be grade I, II, or III. It is usually benign (grade I) and grows slowly.
- Oligodendroglioma: The tumor arises from cells that make the fatty substance that covers and protects nerves. It usually occurs in the cerebrum. It is most common in middle-aged adults. It can be grade II or III.
Among children, the most common types are:
- Medulloblastoma: The tumor usually arises in the cerebellum. It is sometimes called a primitive neuroectodermal tumor. It is grade IV.
- Grade I or II astrocytoma: In children, this lowgrade tumor occurs anywhere in the brain. The most common astrocytoma among children is juvenile pilocytic astrocytoma. It is grade I.
- Ependymoma: The tumor arises from cells that line the ventricles or the central canal of the spinal cord. It is most commonly found in children and young adults. It can be grade I, II, or III.
- Brain stem glioma: The tumor occurs in the lowest part of the brain. It can be a low-grade or high-grade tumor. The most common type is a diffuse intrinsic pontine glioma.
Symptoms of Brain Tumor
The symptoms of a brain tumor depend on tumor size, type, and location. Symptoms may be caused when a tumor presses on a nerve or harms a part of the brain. Also, they may be caused when a tumor blocks the fluid that flows through and around the brain, or when the brain swells because of the buildup of fluid. These are the most common symptoms of brain tumors:
- 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 tumor. 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 Tumors
When you're told that you have a brain tumor, it is natural to wonder what may have caused your disease. But no one knows the exact causes of brain tumors. Doctors seldom know why one person develops a brain tumor and another does not. Researchers are studying whether people with certain risk factors are more likely than others to develop a brain tumor. A risk factor is something that may increase the chance of getting a disease.
Studies have found the following risk factors for brain tumors:
- 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 tumor.
- Family history: It is rare for brain tumors to run in a family. Only a very small number of families have several members with brain tumors.
Diagnosis
If you have symptoms that suggest a brain tumor, 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
- MRI
- CT Scan
- Angiogram
- Spinal Tap
- Biopsy
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 tumor 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 tumor.
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 tumor is present, the x-ray may show the tumor or blood vessels that are feeding into the tumor.
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 tumor 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 tumor, learn what grade it is, and plan treatment.
Treatment Overview
People with brain tumors 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 tumor
- 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.
Radiation Therapy Treatment
Radiation therapy kills brain tumor cells with high-energy x-rays, gamma rays, or protons. Radiation therapy usually follows surgery. The radiation kills tumor cells that may remain in the area. Sometimes, people who cannot have surgery have radiation therapy instead.
Gamma Knife stereotactic radiosurgery is a non-invasive treatment that delivers gamma radiation at the tumor site without making an incision. The high-energy radiation is delivered precisely at the target region minimizing exposure and damage to the surrounding tissues
