What is a brain tumor?

What is a brain tumor?

A brain tumor is an abnormal growth or mass of cells in or around the brain. It is also called a central nervous system tumor.

Brain tumors can be malignant (cancerous) or benign (not cancerous). Some tumors grow quickly; others are slow-growing.

Only about one-third of brain tumors are cancerous. But whether they are cancerous or not, brain tumors can impair brain function if they grow large enough to press on surrounding nerves, blood vessels and tissue.

Tumors that develop in the brain are called primary tumors. Tumors that spread to the brain after forming in a different part of the body are called secondary tumors or metastatic tumors. This article focuses on primary tumors. There are more than 100 types of primary brain and spinal cord tumors.