A brain tumor is a mass of cells within the brain that occupies space. These tumors may be benign (non-cancerous), or malignant (cancerous). Even if a brain tumor is benign and generally shows a controlled rate of growth, they can be dangerous because of the location in the brain. The brain is surrounded by solid skull, which will not allow for significant expansion. When a benign tumor grows, it may press upon normal tissues in the brain, causing them to be impaired or damaged. Therefore, it is very important that both benign and malignant tumors be treated as soon as possible.

Symptoms
Most brain tumors appear in the upper part of the brain in the cerebral hemispheres. This is the region of the brain that controls thought, emotion, reasoning, and language.

Since brain tumors can invade or press on normal brain tissue, symptoms can result from the pressure created. Symptoms typically include headaches, seizures, nausea, vomiting, or weakness/numbness in the arms or legs, and difficulty with speech or thought processing. Because other diseases can also cause these symptoms, it is important to perform diagnostic tests to determine if a brain tumor is present.

Different Types
Brain tumors are identified by the type of cell from which they arose or by the location in the brain where they occur.

Gliomas are the most common type of primary brain tumor. These arise from the connective tissue of the brain. Types of gliomas include astrocytomas, glioblastomas, oligodendrogliomas and ependymomas. These tumors make up approximately 50% of all primary brain tumors.

Meningiomas comprise approximately 25% of brain tumors, with pituitary tumors making up 10% and acoustic neuromas comprising 7.5%. Other tumor types, including chondrosarcomas, germinomas, hemangiomas, teratomas, and chordomas, make up the remaining 7.5%.