Malignant brain tumors are further classified as either primary or secondary tumors. In this report, the term brain tumor will refer only to malignant tumors, unless they are specifically defined as benign. Benign Tumors Benign tumors represent half of all primary brain tumors. Benign tumors can be serious and even life-threatening if they are situated in vital areas in the brain where they exert pressure on sensitive nerve tissue or if they increase the fluid in the brain. While some benign brain tumors may pose a health risk, including risk of disability and death, the majority is usually successfully treated with techniques such as surgery and radiation.
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 metastasize to the brain originate in the lung, breast, kidney, or from melanomas in the skin. Metastatic brain tumors can also occur when cancers in the nasal passages and throat spread to the brain via the nerves in the skull or through areas at the base of the skull. A primary malignant brain tumor is one that originates in the brain itself.