A brain tumor is an abnormal growth of tissue in the brain. Brain tumors may be classified as either benign (non-cancerous) or malignant (cancerous). The tumor can either originate in the brain itself, or come from another part of the body and travel to the brain (metastasis). A benign tumor does not contain cancer cells and usually, once removed, does not recur. Most benign brain tumors do not invade surrounding tissue. Malignant brain tumors contain cancer cells. Malignant brain tumors are usually fast growing and invade surrounding tissue. These tumors very rarely spread to other areas of the body, but may recur after treatment. Whether benign or malignant, an enlarging brain tumor is dangerous because it can damage healthy brain tissue—areas that affect your speech, your mobility, even your thoughts. Metastatic brain tumors are tumors that begin to grow in another part of the body, and then spread to the brain through the bloodstream. Common types of cancer that can travel to the brain include lung cancer, breast cancer, melanoma (a type of skin cancer), and colon cancer. Doctors don’t know the cause of most adult brain tumors, and there are few known risk factors. If a brain tumor is suspected, your doctor may perform procedures such as CT scans, MRIs, X-rays, or biopsies to make a diagnosis. Diagnosis of a brain tumor depends mostly on the types of cells involved and the tumor’s location. A biopsy is performed to analyze the tumor tissue and determine a diagnosis. This is frequently done if the tumor is in an area with sensitive structures around it that may be injured during removal. Surgery is often the first step in the treatment of brain tumors. The goal is to remove as much of the tumor as possible while maintaining neurological function. Other treatments may include chemotherapy; radiation therapy; steroids (to treat and prevent swelling in the brain); anti-seizure medication (to treat and prevent seizures associated with intracranial pressure); rehabilitation (to regain lost motor skills and muscle strength); antibiotics (to treat and prevent infections); and continuous follow-up care (to manage disease, detect recurrence of the tumor, and to manage late effects of treatment). Prognosis greatly depends on all of the following: Specific type of tumor (e.g., meningioma, glioma, glioblastoma) Extent of the disease Size and location of the tumor Presence or absence of metastasis The tumor’s response to therapy Your age, overall health, and medical history Your tolerance of specific medications, procedures, or therapies New developments in treatment As with any cancer, prognosis and long-term survival can vary greatly from person to person. Prompt medical attention and aggressive therapy are important for the best prognosis. Continuous follow-up care is essential for a person diagnosed with a brain tumor. Side effects of radiation and chemotherapy, as well as second malignancies, can occur in survivors of brain tumors.