Around 24,000 Americans are diagnosed with a malignant (cancerous) tumor of the brain or nervous system each year, which makes brain tumors relatively uncommon. Your lifetime risk of developing such a cancer stands at just 0.6%. Nonetheless, a brain tumor diagnosis can feel frightening, especially if it happens to your child. Fortunately, many brain tumors are not cancerous. And survival rates for malignant brain tumors continue to extend, thanks to advances in surgical procedures and other therapies designed to target cancer cells. Researchers have identified about 150 distinct types of brain tumors, including many rare types, but people are most likely to be diagnosed with these common types of brain tumors. Common Benign Brain Tumors Benign brain tumors do not contain any cancer cells and usually grow very slowly, but they can become dangerous if their size eventually puts pressure on adjacent brain structures or other nerve tissues. Adults and children can develop a benign brain tumor, including these common ones: Astrocytomas, the most common brain tumor in children between the ages of 5 and 8. In children these tumors usually are benign and are clinically classified as low-grade gliomas. (In adults, however, astrocytomas often are cancerous, high-grade gliomas, as described below.) Astrocytomas arise in the brain’s glial cells, frequently at the base of the brain in children. Treatment for astrocytomas commonly involves radiation and chemotherapy. Meningiomas, which form in the meninges, the protective tissues that cover the brain and spinal cord. Meningiomas make up 10 to 15% of all brain tumors. Sometimes meningiomas require no treatment beyond monitoring the size of the tumor through imaging. Symptomatic meningiomas often can be surgically removed, which results in a full cure. Schwannomas that develop in the tissues that wrap the nerve cells like the insulation that coats electrical wires. The most common benign nerve tumor in adults, schwannomas often arise in the large nerve that extends from the brain to each ear, resulting in a benign acoustic neuroma that can cause dizziness or loss of hearing in one ear. Acoustic neuromas may be treated with surgery, radiation therapy, or a combination of approaches. Common Malignant Brain Tumors Cancerous brain tumors can occur in two types: primary and secondary (also known as metastatic). Primary malignant brain tumors originate in the brain tissue itself, while secondary tumors result from cancer that spreads to the brain from another part of the body. Primary brain tumors almost always require treatment to stop the cancer from growing or spreading. The most common types of primary malignant brain tumors include: Astrocytomas, as noted above, the most common type of cancerous glioma in adults. These tumors can develop in people of all ages and both sexes, but they are most prevalent in middle-aged men. Astrocytomas can be treated with various therapies, and survival rates depend greatly on the stage of the cancer at diagnosis. Glioblastoma multiforme (GBM), another common form of glioma that, in fact, can be characterized as a very aggressive type of astrocytoma. Glioblastomas tend to grow very quickly and invade surrounding brain tissue at a rapid rate. These malignant brain tumors arise most frequently in men between the ages of 50 and 70, but they can develop in women, too. Medulloblastoma, one of the most common malignant brain tumors in children under age 10. Treatment usually includes surgery to remove the tumor, along with radiation therapy. The prognosis for medulloblastoma varies, depending on the tumor’s specific genetic mutations and gene expression. A brain tumor diagnosis can be frightening, but benign tumors often can be fully treated or even left alone without causing problems. Treatments for malignant brain tumors continues to advance, offering hope to patients facing this challenging condition.