What is a brain tumor?

Brain tumors begin when normal cells in the brain begin to change and mutate. Normal healthy cells die and are replaced. Instead of dying these mutated cells continue to live and increasingly divide into more abnormal cells forming tumors in the membrane, the pituitary gland, the cranial nerves, or the pineal gland. Primary brain tumors refer to tumors that originate in the brain, but more common are secondary brain tumors, also known as metastatic, which occur as a result of cancer from somewhere else in the body. Tumors can be either benign or malignant. Benign tumors are usually not cancer, do not invade nearby tissue, and when removed, do not recur. Malignant tumors are made up of cancer cells. They can press on areas of the brain and disrupt its function and may invade and grow into the healthy tissue around them.