Brain Tumor: The Facts

What is it?

A brain tumor is a type of cancer that originates in the central nervous system (CNS) of the body. The brain is the center of thought, memory, emotion and speech. The spinal cord and cranial nerves, which are special nerves in the head, carry signals between the brain and the rest of the body.

Naming Brain Tumors

There are many different types of brain tumors. Brain tumors get their names from their location, their growth patterns, and the type of cells that are found in the tumor.

• Primary Brain Tumors: Primary tumors are tumors that begin in the brain tissue itself.
  
• Secondary Brain Tumors: Secondary tumors are tumors that result when another type of cancer that started in a different part of the body spreads or "metastasizes" to the brain.
  
• Benign Tumors: A tumor is considered to be benign if it does not contain cancerous cells. Benign tumors have very clear borders and do not extend into the surrounding tissues. A benign tumor can usually be removed during surgery and will not reoccur.
  
• Malignant Tumors: Malignant tumors can contain cancerous cells and often develop "roots" that reach out into other areas of the brain. If a tumor contains cancerous cells but does not develop roots, it is called "encapsulated." A malignant tumor is any tumor containing cancerous cells or not that poses a threat to the normal and vital functions of the brain. These tumors are life threatening.
  

There are many different types of tumors that can be found in the brain. The American Brain Tumor Association has provided the terms below to aid in the naming of certain tumors. The use of these terms within a tumor's name can tell you where the tumor started, and sometimes, what kind of cells are in the tumor.

• Adenoma: Usually a benign tumor that is found in a gland.
  
• Blastoma: A malignant tumor made up of under-developed embryonic cells.
  
• Carcinoma: A malignant tumor that has its origins in the epithelial cells that makes up the skull as well as the inner linings of the body.
  
• Sarcoma: A malignant tumor from the connective tissue or blood vessels of the body, or from the lymphatic system.
  
• Glioma: A tumor that arises from the glial, or supportive tissue, of the brain. This is the most common type of primary brain tumor.
  

Grading Brain Tumors

Doctors use a system known as grading to show the severity of a brain tumor. While the exact method depends on the particular type of tumor, tumors are usually graded from Grade I (the least severe) to Grade IV (very advanced or malignant).

• Grade I tumors tend to have very distinct borders and do not appear to extend into surrounding tissue. They grow very slowly.
  
• Grade II tumors are normally slow growing but can invade surrounding tissue.
  
• Grade III tumors are malignant and invade surrounding normal brain tissue. These tumors tend to recur.
  
• Grade IV tumors are made up of abnormal cells and spread to the surrounding tissue very rapidly.
  

Who gets it?

This type of cancer accounts for approximately 1.4% of all cancers and 2.4% of all cancer-related deaths. Both adults and children are included in these statistics, but only adult tumors will be addressed here.

The large majority of brain cancers are not associated with any risk factors and most brain cancers simply happen for no apparent reason. A few risk factors associated with brain cancer are known:

• Radiation - most radiation-induced brain tumors are caused by radiation to the head given for the treatment of other cancers. At one time, radiation was used to remove all the hair on the head because of lice. Many people then developed brain tumors.
  
• Immune System Disorders - People with impaired immune systems have an increasing risk of developing lymphomas of the brain or spinal cord. Problems of the immune system may be congenital (present at birth), may be a side effect of treatment for other cancers or to prevent rejection of transplanted organs, or the result of the acquired immunodeficiency syndrome (AIDS).
  
• Family History - Rare cases of brain and spinal cord cancers run in families. In general, patients with hereditary cancer syndromes have multiple tumors that occur when they are young.
  

Symptoms

The symptoms seen in patients with brain tumors are often the result of the tumor pushing on different areas of the brain. The skull does not allow a tumor to grow in all directions, so tumor growth results in pressure and swelling of the brain at the site of the tumor. Each section of the brain is responsible for a different function in the body. The location of the tumor will determine how the symptoms are seen in the patients.

Some symptoms can include:

• Headaches that wake the patient up from sleep or are very severe in the morning.
  
• Nausea or vomiting
  
• Weakness in the limbs or difficulty walking and moving
  
• Unexplained seizures
  
• Sleepiness
  
• Changes in personality, memory, or speech abilities

Patients who experience these symptoms are not necessarily suffering from a brain tumor. Many other conditions can cause symptoms identical or similar to those listed above. It is important to see your doctor if you feel that you are having any kind of health problems.

How is it detected?

There are no blood tests or screening tests for diagnosing brain tumors. In most cases, survival is dependent on the type and location of the tumor, not how early it is detected. However, if a patient's symptoms suggest that a brain or spinal cord tumor may be present, in addition to a complete medical history and physical exam, several types of examinations and tests will be done:

• Computed Tomography (CT, CAT) - During a CT scan, the patient lies still as an imaging machine circles around the head. The machine measures the amount of x-rays that pass through the brain and a computer compiles the images to form a 3-D picture.
  
• Magnetic Resonance Imaging (MRI) - An MRI machine is shaped similarly to the machine used in a CT scan. As the patient lies still, the MRI machine emits radio waves. The changes in the movement of atoms in the body show the difference between diseased and healthy tissue.
  
• Magnetic Resonance Spectroscopy - Like an MRI, except that it images substances other than water (the substance that is imaged in a routine MRI).
  
• Positron Emission Tomography (PET) Scan - After injection of a radioactive substance, a PET scanning machine circles the head and records metabolic activity in the brain. Malignant tumors consume chemicals more quickly and this can be seen on the PET scan. This procedure can last for 1-4 hours.
  
• Radionucide (RN) - This test is most effective for tumors that are vascular, or receive a large blood supply from the body. During an RN scan, a radioactive dye is injected into a vein and the path of blood is followed.
  
• Electroencephalogram (EEG) - An EEG is a relatively painless test that measures the electrical activity of the brain. In this test, electrodes are attached to the scalp and a computer reads the brain activity.
  
• Angiography - This is another x-ray imaging study sometimes used in evaluating brain and spinal cord tumors. A special dye is injected into blood vessels near the tumor, and doctors then view the blood supply of a tumor.
  
• Biopsy - A small piece of tissue is removed from the tumor and is studied to determine if and what type of cancer is present. This is the only way that Brain Cancer can be conclusively diagnosed.
  

In addition to scans, doctors can test the levels of certain chemicals in the body in order to detect a tumor.

• Spinal Tap (also called a "Lumbar Puncture") - A spinal tap is a test that requires a collection of spinal fluid. This is done by having the patient lie on his side. A needle is inserted into the patient's back and fluid is withdrawn. The fluid is then tested for certain tumor markers, tumor cells or the presence of certain proteins or chemicals that will indicate a brain tumor.
  

Is it Curable?

Although survival may be prolonged by treatment, most malignant brain tumors are not cured by treatment. However, most benign tumors may be cured through surgery alone or with radiation. Most malignant tumors are not cured by surgery alone because they infiltrate the surrounding healthy brain tissue.

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