Adult Brain Tumors

Adult brain tumors are diseases in which cancer (malignant) cells begin to grow in the tissues of the brain. Tumors that start in the brain are called primary brain tumors. Estimated new cases and deaths from brain and other nervous system tumors in the United States in 2007:

• New cases: 20,500 
• Deaths: 12,740

Symptoms and Diagnosis

A doctor should be seen if the following symptoms appear:

• Frequent headaches.
• Vomiting.
• Loss of appetite.
• Changes in mood and personality.
• Changes in ability to think and learn.
• Seizures.

To diagnose brain tumors, the following tests and procedures may be used:

• CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
• MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of the brain and spinal cord. A substance called gadolinium is injected into the patient through a vein. The gadolinium collects around the cancer cells so they show up brighter in the picture. This procedure is also called nuclear magnetic resonance imaging (NMRI).
• Biopsy: It is done by removing part of the skull and using a needle to remove a sample of the brain tissue. A pathologist views the tissue under a microscope to look for cancer cells. If cancer cells are found, the doctor will remove as much tumor as safely possible during the same surgery. An MRI may then be done to determine if any cancer cells remain after surgery. Tests are also done to find out the grade of the tumor.

Grades

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. The pathologist determines the grade of the tumor using tissue removed for biopsy. 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.

Causes

All cancers are caused by dysfunctions of proteins involved in cell division, apoptosis, or DNA repair (see general characteristics). Dysfunctional proteins may arise from gene mutations or protein interactions with environments.

In a small number of individuals, primary brain tumors may result from specific genetic diseases - such as neurofibromatosis and tuberous sclerosis - or exposure to radiation or cancer-causing chemicals. Although smoking, alcohol consumption, and certain dietary habits are associated with some types of cancers, they have not been linked to primary brain and spinal cord tumors.

Reference:

National Cancer Institute, USA.