What are Brain Tumors?

Normal cells grow, divide and reproduce when necessary for development, growth and repair. During cell division, control mechanisms ensure that cells do not divide continually without restraint. When this control mechanism is broken, cells divide and reproduce indefinitely. This is how a tumor begins.

Brain tumors are abnormal growths of cells in or directly around the brain. Types of tumors vary, and are classified as either benign or malignant, and either primary or secondary brain tumors.

Brain Tumor Symptoms

Brain tumor symptoms vary greatly, depending on the tumor's size and location as well as the age of the patient. Some common brain tumor symptoms include:

• Double vision
• Headaches
• Loss of sensation or movement in an extremity
• Nausea
• Seizures
• Unexplained change in personality or mood
• Vision, hearing and/or speech impairments.

Types of Tumors

Brain tumors are classified as either benign or malignant, meaning they were formed by noncancerous or cancerous cells, respectively. Benign tumors are usually removed and do not grow back, but malignant tumors can be fatal. Both types of brain tumors are dangerous due to increased pressure in the brain and surrounding areas.

Primary Brain Tumors

A primary brain tumor can originate in any of the brain's tissues, including the:

• Cranial nerves
• Pituitary or pineal glands
• Meninges (membranes covering the brain and spinal cord).

Brain tumors are named for the cells from which they originate. The most common types of primary brain tumors are gliomas originating in the glial cells, whose function is to protect neurons. Some examples of gliomas include:

• Astrocytoma: Begins in astrocyte cells mainly in the cerebrum.
• Brainstem glioma: Begins in cells of the brain stem.
• Ependymoma: Begins in cells lining the ventricles or central canal of the spinal cord.
• Oligodendroglioma: Begins in cells covering nerves mainly in the cerebrum.

Although the cause of primary brain tumors is unknown, certain risk factors are associated with an increased risk of developing a primary brain tumor, including:

• Age: Adults 70 years and older, and children younger than eight
• Family history: Family history of gliomas
• Occupation: Radiation or formaldehyde and other chemical exposure
• Race: Caucasians
• Sex: Males.

Secondary Brain Tumors

Secondary brain tumors develop when cancer spreads to the brain from somewhere else in the body. This more common type of brain tumor is also called a "metastatic tumor." Any type of cancer can move into the brain, but some of the most common types to spread include:

• Breast cancer
• Colon cancer
• Kidney cancer
• Lung cancer.

Resources

Children's Hospital of Wisconsin Staff. Brain tumors. Retrieved April 4, 2010, from the Children's Hospital of Wisconsin website: http://www.chw.org/display/PPF/DocID/22484/router.asp.

Mayo Foundation for Medical Education and Research Staff. (2008). Brain tumor. Retrieved on March 20, 2010, from the Mayo Clinic website: http://www.mayoclinic.com/health/brain-tumor/DS00281.

MedicineNet, Inc. Staff. (n.d.). Brain tumor. Retrieved on March 20, 2010, from the MedicineNet.com website: http://www.medicinenet.com/brain_tumor/article.htm.