Brain Cancer

Background

The brain and spinal cord together make up the central nervous system. Tumors that originate in brain tissue are called primary brain tumors.

The National Cancer Institute reports that more than 17,000 Americans are diagnosed with primary brain cancer each year. While brain tumors can develop at any age, studies show that they occur most commonly in children younger than eight years old and adults over age 70.

Primary brain tumors are categorized by the type of tissue in which they first develop.

The most common brain tumors are called gliomas, which originate in the glial (supportive) tissue.

Types of gliomas include:

• Astrocytomas develop from small, star-shaped cells called astrocytes. They may arise anywhere in the brain or spinal cord. In adults, astrocytomas most often occur in the cerebrum, which is the largest part of the brain.
• Glioblastomas, also called glioblastoma multiforme or grade IV astrocytoma, are malignant astrocytomas that grow and spread aggressively. Glioblastomas occur most often in adults between the ages of 45 and 70.
• Brain stem gliomas arise in the brain stem. The brain stem connects the brain with the spinal cord. Tumors in this area can be difficult to treat. Most brain stem gliomas are high-grade astrocytomas.
• Ependymomas usually occur in the lining of the ventricles, or spaces in the brain and around the spinal cord. Although ependymomas can develop at any age, these tumors most commonly arise in children and adolescents.
• Oligodendrogliomas develop in the cells that produce myelin, the fatty covering that protects nerves in the brain and spinal cord. These tumors are very rare, and usually occur in the cerebrum. They are slow growing and generally do not spread into surrounding brain tissue. While they occur most often in middle-aged adults, these tumors have been found in people of all ages.

Types of brain tumors that do not begin in glial tissue, include:

• Meningiomas grow from the meninges, the thin membranes that surround the brain and spinal cord. These tumors are usually benign. Because these tumors tend to grow very slowly, the brain may be able to adjust to their presence. Meningiomas frequently grow quite large before they cause symptoms. They occur most often in women ages 30 to 50.
• Craniopharyngiomas develop in the area of the brain near the pituitary gland near the hypothalamus. These tumors are usually benign. However, they may sometimes be considered malignant because they may create pressure on, or damage, the hypothalamus and affect vital functions (such as body temperature, hunger and thirst). These tumors occur most often in children and adolescents or in adults over age 50.
• Germ cell tumors arise from developing sex (egg or sperm) cells, also known as germ cells. The most common type of germ cell tumor in the brain is the germinoma. Aside from the brain, germinomas can form in the ovaries, testicles, chest, and abdomen. Most germ cell tumors occur in children.
• Pineal region tumors occur in or around the pineal gland, a small organ in the center of the brain. The pineal gland produces melatonin, a hormone that plays an important role in the sleep-wake cycle. These tumors can be slow growing (pineocytoma) or fast growing (pineoblastoma). Since the pineal region is very hard to reach, it is often difficult to remove these tumors.
• Medulloblastomas are fast-growing brain tumors that develop from the neurons of the cerebellum in the lower back of the brain. These tumors are usually found in children or young adults.

Symptoms

Symptoms of brain tumors can include:

• New onset or change in pattern of headaches
• Headaches that gradually become more frequent and more severe
• Unexplained nausea or vomiting
• Changes in vision, such as blurred vision, double vision or loss of peripheral vision
• Change or loss of muscle and/or sensory control
• Difficulty with balance
• Speech difficulties
• Confusion in everyday matters
• Personality or behavior changes
• Seizures
• Hearing problems
• Hormonal (endocrine) disorders

Risk Factors

• Being exposed to vinyl chloride may increase the risk of glioma.
• Past treatment with radiation therapy to the head may increase the risk of meningioma.
• Infection with the Epstein-Barr virus, having AIDS (acquired immunodeficiency syndrome), or receiving an organ transplant may increase the risk of primary lymphoma of the brain.
• Having certain genetic syndromes may increase the risk of developing the following types of brain tumors: Neurofibromatosis, type 1 or 2, von Hippel-Lindau disease, Tuberous sclerosis, Li-Fraumeni syndrome, Turcot syndrome (type 1 and type 2), Klinefelter syndrome, or Nevoid basal cell carcinoma.

Staging

There is no formal staging process for primary brain cancer. Brain cancer does not behave in the same way and almost never spreads away from the central nervous system. The prognosis and treatment is determined by the characteristics of the tumor and the affect the tumor has on functionality.

• Size and location
• Type of tissue or cells
• Grade of the tumor and the aggressiveness of tumor growth; Lower grade tumors are less likely to spread.
• Resectability; The likelihood that part or the entire tumor can be removed by surgery
• Whether the cancer has just been diagnosed or has recurred
• The patient's general health

Treatment

Treatment for a brain tumor depends on the type, size, and location of the tumor, and overall patient health.

Surgery
If the brain tumor is located in a place that makes it accessible for an operation, the treatment goal is to remove as much of your brain tumor as possible. In some cases, tumors are small and easy to separate from surrounding brain tissue, which makes complete surgical removal possible. In other cases, tumors are located near sensitive areas in your brain, making surgery risky. In these situations your doctor may try to remove as much of the tumor as is safe. Even removing a portion of the brain tumor may help reduce symptoms. In some cases only a small biopsy is taken to confirm the diagnosis.

Radiation therapy
External beam radiation can focus just on one part of the brain where the tumor is located, or it can be applied to the entire brain (whole brain radiation). Whole brain radiation is sometimes used after surgery to kill tumor cells that might have been left behind. Whole brain radiation may also be an option for brain tumors that cannot be removed through surgery. Whole brain radiation is also used in patients where cancer has metastasized to the brain.

Radiosurgery
Radiosurgery uses multiple focused beams of high-dose radiation aimed directly at the brain cancer. This causes less damage to nearby healthy tissue. This is not a surgical procedure and is also called stereotactic radiosurgery. Radiosurgery may be an option if your brain tumor can't be removed with traditional surgery.

Chemotherapy
Chemotherapy may involve administration of pills or intravenous medication. Chemotherapy drugs can also be administered into your spinal column, so that treatment is concentrated within the central nervous system.

Another type of chemotherapy can be placed during surgery. When removing all or part of the brain tumor, the surgeon may place wafers or discs containing chemotherapy medications at the site of surgery within the brain.

Rehabilitation after treatment
Because brain tumors can develop in parts of the brain that control motor skills, speech, vision and thinking, rehabilitation may be a necessary part of recovery. The brain can sometimes heal itself after trauma from or treatment of a brain tumor — but this can take time and patience. Your physician will help determine what rehabilitation programs will be appropriate for you after your treatment therapy.

References
National Cancer Institute, Mayo Clinic, Cancer Treatment Centers of America.