context: When you are diagnosed with brain cancer, learning as much as you can about it can help you decide on the best treatment for you. This guide helps you learn the basics on the types of brain cancer and how they are treated. A brain tumor is a mass of cells in your brain that are not normal. There are two general groups of brain tumors: Primary brain tumors start in brain tissue and tend to stay there. Secondary brain tumors are more common. These cancers start somewhere else in the body and travel to the brain. Lung, breast, kidney, colon, and skin cancers are among the most common cancers that can spread to the brain. Some brain tumors contain cancer cells and others don't: Benign brain tumors don't have cancer cells. They grow slowly, can often be removed, and rarely spread to the brain tissue around them. They can cause problems if they press on certain areas of the brain, though. Depending on where they are located in the brain, they can be life-threatening. Malignant brain tumors have cancer cells. The rates of growth vary, but cells can invade healthy brain tissue nearby. Malignant tumors rarely spread beyond the brain or spinal cord. Tumors are graded by how normal or abnormal the cells look. Your doctor will use this measurement to help plan your treatment. The grading also gives you an idea of how fast the tumor may grow and spread. Grade 1. The cells look nearly normal and grow slowly. Long-term survival is likely. Grade 2. The cells look slightly abnormal and grow slowly. The tumor may spread to nearby tissue and can recur later, maybe at a more life-threatening grade. Grade 3. The cells look abnormal and are actively growing into nearby brain tissue. These tumors tend to recur. Grade 4. The cells look most abnormal and grow and spread quickly. Some tumors change. Rarely some benign tumors can turn malignant, and a lower-grade tumor may return at a higher grade. In adults, the most common types of brain cancer are: Astrocytomas. These usually arise in the largest part of the brain, the cerebrum. They can be any grade. They often cause seizures or changes in behavior. Meningiomas . These are the most common primary brain tumors in adults. They are most likely to occur in your 70s or 80s. They arise in the meninges, the lining of the brain. They can be grade 1, 2, or 3. They are often benign and grow slowly. Oligodendrogliomas. These arise in the cells that make the covering that protects nerves. They are usually grade 1, 2, or 3. They usually grow slowly and don't spread to nearby tissue. Your treatment will depend on the type and grade of the cancer, where it's located, its size, and your age and health. Surgery is usually the first treatment. For grade 1 tumors, it may be enough. It's possible that all the cancer can be removed. But even if it isn't, the surgery can reduce the size and ease symptoms. Radiation therapy is used after surgery to kill any tumor cells that remain in the area. If surgery isn't an option, you may have only radiation therapy. Chemotherapy is sometimes used to kill brain cancer cells. It is given by mouth, IV, or, less often, in wafers a surgeon puts in the brain. Targeted therapy can be used to treat certain types of brain tumors. These drugs attack specific parts of cancer cells and help stop tumors from growing and spreading. Your doctor may also recommend combined therapies. If you have cancer, it's important to follow your treatment plan, work with your doctor, and go to your regularly scheduled appointments.