Brain Cancer

OverView:
The brain is a soft, spongy mass of tissue. It is protected by:

  • The bones of the skull
  • Three thin layers of tissue (meninges)
  • Watery fluid (cerebrospinal fluid) that flows through spaces between the meninges and through spaces (ventricles) within the brain

Brain1
Brain and nearby structures

The brain directs the things we choose to do (like walking and talking) and the things our body does without thinking (like breathing). The brain is also in charge of our senses (sight, hearing, touch, taste, and smell), memory, emotions, and personality.

A network of nerves carries messages back and forth between the brain and the rest of the body. Some nerves go directly from the brain to the eyes, ears, and other parts of the head. Other nerves run through the spinal cord to connect the brain with the other parts of the body.
Within the brain and spinal cord, glial cells surround nerve cells and hold them in place.

The three major parts of the brain control different activities:

  • Cerebrum: The cerebrum uses information from our senses to tell us what is going on around us and tells our body how to respond. It controls reading, thinking, learning, speech, and emotions.
    The cerebrum is divided into the left and right cerebral hemispheres. The right hemisphere controls the muscles on the left side of the body. The left hemisphere controls the muscles on the right side of the body.
  • Cerebellum: The cerebellum controls balance for walking and standing, and other complex actions.
  • Brain stem: The brain stem connects the brain with the spinal cord. It controls breathing, body temperature, blood pressure, and other basic body functions.

Brain2
Major parts of the brain

Tumor Grade:
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.

Cells from low-grade tumors (grades I and II) look more normal and generally grow more slowly than cells from high-grade tumors (grades III and IV).

Over time, a low-grade tumor may become a highgrade tumor. However, the change to a high-grade tumor happens more often among adults than children. 

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.
    • Grade I or II astrocytoma: It may be called a low-grade glioma.
    • Grade III astrocytoma: It's sometimes called a high-grade or an anaplastic astrocytoma.
    • Grade IV astrocytoma: It may be called a glioblastoma or malignant astrocytic glioma.
  • Meningioma: The tumor arises in the meninges. It can be grade I, II, or III. It's 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's 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's 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's grade I.
  • Ependymoma: The tumor 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 tumor occurs in the lowest part of the brain. It can be a low-grade or high-grade tumor. The most common type is diffuse intrinsic pontine glioma.

Risk Factors:
When you're told that you have a brain tumor, it's 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 doesn't.

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. People exposed to ionizing radiation may have an increased risk of a brain tumor, such as meningioma or glioma.
  • 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.

Researchers are studying whether using cell phones, having had a head injury, or having been exposed to certain chemicals at work or to magnetic fields are important risk factors. Studies have not shown consistent links between these possible risk factors and brain tumors, but additional research is needed.

Screening:
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: 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.

Your doctor may ask for other tests:

  • 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). This procedure is performed with local anesthesia. The doctor uses a long, thin needle to remove fluid from the lower part of the spinal column. A spinal tap takes about 30 minutes. You must lie flat for several hours afterward to keep from getting a headache. A laboratory checks the fluid for cancer cells or other signs of problems.
  • 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.

Surgeons can obtain tissue to look for tumor cells in two ways:

  • Biopsy at the same time as treatment: The surgeon takes a tissue sample when you have surgery to remove part or all of the tumor. See the Surgery section.
  • Stereotactic biopsy: You may get local or general anesthesia and wear a rigid head frame for this procedure. The surgeon makes a small incision in the scalp and drills a small hole (a burr hole) into the skull. CT or MRI is used to guide the needle through the burr hole to the location of the tumor. The surgeon withdraws a sample of tissue with the needle. A needle biopsy may be used when a tumor is deep inside the brain or in a part of the brain that can't be operated on.

However, if the tumor is in the brain stem or certain other areas, the surgeon may not be able to remove tissue from the tumor without harming normal brain tissue. In this case, the doctor uses MRI, CT, or other imaging tests to learn as much as possible about the brain tumor.

Symptoms:
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:

  • Headaches (usually worse in the morning)
  • Nausea and vomiting
  • Changes in speech, vision, or hearing
  • Problems balancing or walking
  • Changes in mood, personality, or ability to concentrate
  • Problems with memory
  • Muscle jerking or twitching (seizures or convulsions)
  • Numbness or tingling in the arms or legs

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.

Treatment:
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

For some types of brain cancer, the doctor also needs to know whether cancer cells were found in the cerebrospinal fluid.

Your doctor can describe your treatment choices, the expected results, and the possible side effects. Because cancer therapy often damages healthy cells and tissues, side effects are common. Before treatment starts, ask your health care team about possible side effects and how treatment may change your normal activities. You and your health care team can work together to develop a treatment plan that meets your medical and personal needs.

You may want to talk with your doctor about taking part in a clinical trial, a research study of new treatment methods. See the Taking Part in Cancer Research section.

Your doctor may refer you to a specialist, or you may ask for a referral. Specialists who treat brain tumors include neurologists, neurosurgeons, neuro-oncologists, medical oncologists, radiation oncologists, and neuroradiologists.

Your health care team may also include an oncology nurse, a registered dietitian, a mental health counselor, a social worker, a physical therapist, an occupational therapist, a speech therapist, and a physical medicine specialist. Also, children may need tutors to help with schoolwork.

Surgery
Surgery is the usual first treatment for most brain tumors. Before surgery begins, you may be given general anesthesia, and your scalp is shaved. You probably won't need your entire head shaved.

Surgery to open the skull is called a craniotomy. The surgeon makes an incision in your scalp and uses a special type of saw to remove a piece of bone from the skull.

You may be awake when the surgeon removes part or all of the brain tumor. The surgeon removes as much tumor 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.

After the tumor is removed, the surgeon covers the opening in the skull with the piece of bone or with a piece of metal or fabric. The surgeon then closes the incision in the scalp.

Sometimes surgery isn't possible. If the tumor is in the brain stem or certain other areas, the surgeon may not be able to remove the tumor without harming normal brain tissue. People who can't have surgery may receive radiation therapy or other treatment. You may have a headache or be uncomfortable for the first few days after surgery. However, mediccan usually control pain. Before surgery, you should discuss the plan for pain relief with your health care team. After surgery, your team can adjust the plan if you need more relief.

You may also feel tired or weak. The time it takes to heal after surgery is different for everyone. You will probably spend a few days in the hospital.

Other, less common problems may occur after surgery for a brain tumor. The brain may swell or fluid may build up within the skull. The health care team will monitor you for signs of swelling or fluid buildup. You may receive steroids to help relieve swelling. A second surgery may be needed to drain the fluid. The surgeon may place a long, thin tube (shunt) in a ventricle of the brain. (For some people, the shunt is placed before performing surgery on the brain tumor.) The tube is threaded under the skin to another part of the body, usually the abdomen. Excess fluid is carried from the brain and drained into the abdomen. Sometimes the fluid is drained into the heart instead.

Infection is another problem that may develop after surgery. If this happens, the health care team will give you an antibiotic.

Brain surgery may harm normal tissue. Brain damage can be a serious problem. It can cause problems with thinking, seeing, or speaking. It can also cause personality changes or seizures. Most of these problems lessen or disappear with time. But sometimes damage to the brain is permanent. You may need physical therapy, speech therapy, or occupational therapy.

Radiation Therapy
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 can't have surgery have radiation therapy instead.

Doctors use external and internal types of radiation therapy to treat brain tumors:

  • 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 tumor, the radiation may be aimed at the tumor and nearby brain tissue, or at the entire brain. Some people need radiation aimed at the spinal cord also. The treatment schedule depends on your age, and the type and size of the tumor. Fractionated external beam therapy is the most common method of radiation therapy used for people with brain tumors. Giving the total dose of radiation over several weeks helps to protect healthy tissue in the area of the tumor. 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.
  • Some treatment centers are studying other ways of delivering external beam radiation therapy:
    • Intensity-modulated radiation therapy or 3-dimensional conformal radiation therapy: These types of treatment use computers to more closely target the brain tumor to lessen the damage to healthy tissue.
    • Proton beam radiation therapy: The source of radiation is protons rather than x-rays. The doctor aims the proton beam at the tumor. The dose of radiation to normal tissue from a proton beam is less than the dose from an x-ray beam.
    • Stereotactic radiation therapy: Narrow beams of x-rays or gamma rays are directed at the tumor from different angles. For this procedure, you wear a rigid head frame. The therapy may be given during a single visit (stereotactic radiosurgery) or over several visits.
  • Internal radiation therapy (implant radiation therapy or brachytherapy): Internal radiation isn't commonly used for treating brain tumors 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. The health care team can suggest ways to help you cope with this problem. Radiation therapy also may cause you to become very tired with each radiation treatment. Resting is important, but doctors usually advise people to try to stay as active as they can.

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.

Sometimes radiation therapy causes brain tissue to swell. You may get a headache or feel pressure. The health care team watches for signs of this problem. They can provide medicine to reduce the discomfort. Radiation sometimes kills healthy brain tissue. Although rare, this side effect can cause headaches, seizures, or even death.

Radiation may harm the pituitary gland and other areas of the brain. For children, this damage could cause learning problems or slow down growth and development. In addition, radiation increases the risk of secondary tumors later in life.

 Source: National Cancer Institute