Brain Tumors

Brain tumors are cancer(malignant) cells in the brain. The type depends on the location of the tumor in the brain and the type of brain cells involved. Brain tumors can cause sseizures, paralysis, and death. Treatment consists of surgery, radiation, chemotherapy, and some other approaches under investigation.

Magnetic resonance imaging of a brain during treatment of a tumor. (A) The first scan shows a tumor in the right and left frontal lobe (near the top of the image) as well as the right thalamus. (B) Treatment almost completely removed the tumor. (C) Recurrence of the tumor despite maintenance chemotherapy. (D) The tumor increase in size two months after radiotherapy. (E) Despite therapy the tumor continued to grow. (F) Switching treatments caused the tumor to shrink. Source: Wikimedia Commons

Types

Tumors that start in the brain are called primary brain tumors. Primary brain tumors may spread within the central nervous system (brain and Spinal Cord|spinal cord), but they rarely spread to other parts of the body. But often brain tumors form as a result of cancer cells migrating to the brain from other tissues that have become cancerous. This process is called metastasis, and the brain tumors formed in this way are called metastatic brain tumors.

The extent or spread of cancer is usually classified as being a certain stage. The potential aggressiveness of a tumor can be determined by looking at a sample under the microscope and assigning the tumor a grade based on microscopic features. There is no one universal standard staging system for brain tumors. On the other hand, the World Health Organization has standardized criteria for assignment of tumor grades. A brain tumor can have one of four grades -- with grade I being the slowest growing tumor class with the least likelihood of recurrence after surgical removal, and grade IV being the fastest growing class with the highest likelihood of recurrence after surgery.

Brain stem gliomas

These are tumors that form in the brain stem, the part of the brain connected to the spinal cord. Brain stem gliomas that are high-grade or spread widely throughout the brain stem are difficult to treat successfully.

Pineal astrocytic tumors

Pineal astrocytic tumors form in or near the pineal gland, a tiny organ in the brain that produces the hormonemelatonin. Melatonin helps control sleep and wake cycles.

Glioblastoma (grade IV)

Glioblastomas grow and spread aggressively. The cells look very different from normal cells. Glioblastoma is also called glioblastoma multiforme or grade IV astrocytoma. It occurs most often in adults between the ages of 45 and 70 years.

Oligodendroglial tumors

Oligodendroglial tumors begin in the brain cells called oligodendrocytes, which support and nourish nerve cells. Grade 2 tumors are slow-growing, with cells that look very much like normal cells. Grade 3 tumors grow quickly and the cells look very different from normal cells.

Mixed gliomas

Mixed gliomas are brain tumors that contain more than one type of cell. The prognosis is determined by whichever cell type in the tumor has the highest grade. An example of a mixed glioma is oligoastrocytoma, which contains two kinds of cells, astrocytes and oligodendrocytes.

Ependymal tumors

Ependymal tumors usually begin in cells that line the spaces in the brain and around the spinal cord. These spaces contain cerebrospinal fluid, a liquid that cushions and protects the brain and spinal cord.

Medulloblastoma (grade IV)

Medulloblastomas are brain tumors that begin in the lower back of the brain. They are formed from abnormal brain cells at a very early stage in development. Medulloblastomas are usually found in children or young adults between the ages of 21 and 40 years. This type of cancer may spread from the brain to the spine through the cerebrospinal fluid.

Pineal parenchymal tumors

Pineal parenchymal tumors form from parenchymal cells or pinocytes, the cells that make up most of the pineal gland. These are different from pineal astrocytic tumors that form in tissue that supports the pineal gland.

Meningeal tumors

Meningeal tumors form in the meninges, thin layers of tissue that cover the brain and spinal cord.

Germ cell tumor

Germ cell tumors arise from germ cells, which are meant to form sperm in the testicles or eggs in the ovaries. These cells may travel to other parts of the body and form tumors. Types of germ cell tumors include germinomas, embryonal cell carcinomas, choriocarcinomas, and teratomas. They can occur anywhere in the body and can be either benign or malignant. When they occur in brain, they usually form in its center near the pineal gland, and can spread to other parts of the brain and spinal cord.

Craniopharyngioma (grade II)

Craniopharyngioma occurs in the sellar region of the brain, near the pituitary gland. The pituitary gland is a small organ about the size of a pea, located at the base of the brain. This gland controls many of the body's hormonal functions, especially growth. In adults, these tumors occur most often after the age of 50 years.

Other adult brain tumors

• Recurrent adult brain tumor are tumors that have recurred (come back) after they have been treated. Adult brain tumors often recur, sometimes many years after the first tumor. The tumor may come back in the brain or in other parts of the body.

Signs and Symptoms

Symptoms of brain tumors include the following:

• Frequent headaches
• Vomiting
• Loss of appetite
• Changes in mood and personality
• Changes in ability to think and learn
• New-onset seizures

Diagnosis

Diagnosing brain tumors is done with brain scans and biopsies. The grade of the tumor is assessed to help guide treatment.

Exams and tests

Computed tomography (CT, CAT, or computerized tomography scan), MRI (magnetic resonance imaging), and nuclear magnetic resonance imaging scans of the brain are used to diagnose a brain tumor.

Biopsies of brain tissue are done to confirm diagnosis. Biopsies involve removing a piece of brain tissue with an needle. If cancer cells are found, sometimes the tumor is removed at the same time as the biopsy.

Tumor grade

The grade of a tumor refers to how abnormal the cancer cells look under a microscope and how quickly the tumor is likely to grow and spread. Cells removed by biopsy are used for grading. The following grading system may be used for adult brain tumors:

Grade I

The tumor grows slowly, has cells that look similar to normal cells, and rarely spreads into nearby tissues. It may be possible to remove the entire tumor by surgery.

Grade II

The tumor grows slowly, but may spread into nearby tissue and may become a higher-grade tumor.

Grade III

The tumor grows quickly, is likely to spread into nearby tissue, and the tumor cells look very different from normal cells.

Grade IV

The tumor grows very aggressively, has cells that look very different from normal cells, and is difficult to treat successfully.

Treatment

For treatment, brain tumors are classified by the type of cell in which the tumor began, the location of the tumor in the central nervous system, and the grade of the tumor. The choice of treatment depends on the type, grade, and location of the tumor. Several different treatments are available for adult brain tumors:

• Surgery: Surgery is the first treatment option considered. As much of the tumor is removed as possible to reduce the risk of recurrence.

• Radiation Therapy|Radiation therapy: Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells. There are two types of radiation therapy.

• Chemotherapy: Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping the cells from dividing.

• New methods of delivering radiation therapy
  • Radiosensitizers: Drugs that make tumor cells more sensitive to radiation. Combining radiation with radiosensitizers may kill more tumor cells.
  • Hyperfractionation: Radiation therapy given in smaller-than-usual doses two or three times a day instead of once a day.
  • Stereotactic radiosurgery: A radiation therapy technique that delivers radiation directly to the tumor with less damage to healthy tissue.

• Hyperthermia therapy–Hyperthermia therapy is a treatment in which body tissue is exposed to high temperatures to damage and kill cancer cells, or to make cancer cells more sensitive to the effects of radiation and certain anticancer drugs.

• Biologic therapy–Also called biotherapy or immunotherapy, biologic therapy is a treatment that uses compounds made by the immune system to fight the tumor. These compounds are made in a laboratory and administered to the patient to boost, direct, or restore the body's natural defenses against cancer.

Recurrent brain tumors

Tumors can recur after initial treatment. Approaches to treating these recurrences include surgery, radiation (if not used previously), and chemotherapy. Some patients may be eligible to be enrolled in a clinical trial of investigational drugs.

Metastatic brain tumors

Tumors that have spread to other parts of the brain are usually removed by surgery. If more than one metastasis exists, radiation and surgery are attempted. Surgery is used for large tumors that are pressing on areas of the brain and causing symptoms.

Expected Outcome

The chance of recovery (prognosis) depends on several factors:

• Age: Patients younger than 60 years old fair better than those older than 60 years.
• Number of tumors: Outcomes are best when fewer than three tumors are present.
• Location of the tumors in the brain and/or spinal cord
• How well the tumor responds to treatment.
• Whether the primary tumor continues to grow or spread

The prognosis is better for brain metastases from breast cancer than from other types of primary cancer. The prognosis is worse for brain metastases from colon cancer.

Epidemiology

The American Cancer Society estimated that 16,800 new brain tumors were diagnosed in 1999. In, the United States, more than 100,000 adults die annually from cancers that have spread to the brain.^[1]

Controversy

The use of cell phones has been linked to the development of brain tumors in some epidemiological studies. Other studies have refuted this claim the link remains controversial and needs to be investigated in well-designed, long-term studies (see video below).

Famous people

• US Senator Ted Kennedy (D-MA) was diagnosed with a malignant left parietal lobe glioma in May, 2008 after suffering a seizure.
• Cyclist Lance Armstrong had testicular cancer that metastasized to his brain. After treatment, he achieved great success in the Tour de France.

References

1. ↑ Huff JS. eMedicine Web site. Neoplasms, Brain

External Links

American Brain Tumor Association

National Brain Tumor Society

Pediatric Brain Tumor Foundation