Brain metastases occur when cancer cells spread from their original site to the brain. Any cancer can spread to the brain, but the types most likely to cause brain metastases are lung, breast, colon, kidney and melanoma. Brain metastases may form one tumor or many tumors in the brain. Most patients with brain metastases from extracranial primary tumors such as lung or breast cancer receive palliative treatment approaches, because the common pattern of polymetastatic spread may cause compromised performance status (PS) and eventually also limited survival, often in the range of 3–9 months. Brain metastases may form one tumor or many tumors in the brain. As the metastatic brain tumors grow, they create pressure on and change the function of surrounding brain tissue. This causes signs and symptoms, such as headache, personality changes, memory loss and seizures. Treatment for people whose cancer has spread to the brain may include surgery, radiation therapy, chemotherapy, immunotherapy or a combination of treatments. Other treatments might be recommended in certain situations. Treatment is often focused on reducing pain and symptoms resulting from the cancer. f it's suspected that you have brain metastases, your doctor may recommend a number of tests and procedures. A neurological exam. A neurological exam may include, among other things, checking your vision, hearing, balance, coordination, strength and reflexes. Difficulty in one or more areas may provide clues about the part of your brain that could be affected by a brain tumor. Magnetic resonance imaging (MRI) is commonly used to help diagnose brain metastases. A dye may be injected through a vein in your arm during your MRI study. A number of specialized MRI scan components — including functional MRI, perfusion MRI and magnetic resonance spectroscopy — may help your doctor evaluate the tumor and plan treatment. Other imaging tests may include computerized tomography (CT) and positron emission tomography (PET). For example, if the primary tumor causing your brain metastases is unknown, you might have a chest CT scan to look for lung cancer. Collecting and testing a sample of abnormal tissue (biopsy). A biopsy can be performed as part of an operation to remove a brain tumor, or it can be performed using a needle. The biopsy sample is then viewed under a microscope to determine if it is cancerous (malignant) or noncancerous (benign) and whether the cells are metastatic cancer or from a primary tumor. This information is critical to establish a diagnosis and a prognosis and to guide treatment. Treatment for brain metastases can help ease symptoms, slow tumor growth and extend life. Even with successful treatment, brain metastases often recur, so your doctor will recommend close follow-up after treatment. Treatment options for people with brain metastases often include medication, surgery, stereotactic radiosurgery, whole-brain radiation therapy or some combination of these. In certain situations, your treatment team may consider drug treatments for brain metastases. What treatments are best for you will depend on the type, size, number and location of the tumors, as well as your signs and symptoms, overall health, and preferences. Talk with your doctor about your goals for treatment.