Brain tumor

WHAT ARE BRAIN TUMORS?

Brain tumors are composed of cells that exhibit unrestrained growth in the brain.
Malignant brain tumors are further classified as either primary or secondary tumors. Primary tumors start in the brain, whereas secondary tumors spread to the brain from another site such as the breast or lung. (In this report, the term "brain tumor" will refer mainly to primary malignant tumors, unless otherwise specified.)

Secondary (Metastatic) Malignant Brain Tumors

A secondary (metastatic) brain tumor occurs when cancer cells spread to the brain from a primary cancer in another part of the body. Secondary tumors are about three times more common than primary tumors of the brain. Usually, multiple tumors develop. Solitary metastasized brain cancers may occur but are less common. Most often, cancers that spread to the brain to cause secondary brain tumors originate in the lung, breast, kidney, or from melanomas in the skin.