Brain cancer is a disease of the brain where cancer cells (malignant) grow in the brain tissue. Cancer cells grow to form a mass of cancer tissue (tumor) that interferes with brain tissue functions such as muscle control, sensation, memory, and other normal body functions. Tumors composed of cancer cells are called malignant tumors, and those composed of noncancerous cells are called benign tumors. Cancer cells that develop from brain tissue are called primary brain tumors. Statistics suggest that brain cancer is not rare and is likely to develop in about 20,000 people per year.
There are two main types of brain cancer. Primary brain cancer starts in the brain. Metastatic brain cancer starts somewhere else in the body and moves to the brain. Brain tumors can be benign, with no cancer cells, or malignant, with cancer cells that grow quickly.
Primary brain cancer rarely spreads beyond the central nervous system, and death results from uncontrolled tumor growth within the limited space of the skull. Metastatic brain cancer indicates advanced disease and has a poor prognosis.