context: Chordoma is a kind of cancer that grows in the bones of your skull and spine. It's very rare. Only 1 out of every 1 million people gets it. About 300 people are diagnosed with chordoma in the United States each year. You can get it at any age -- even in childhood. But most people are diagnosed between ages 40 and 70. Men get it more often than women. Chordomas can form anywhere in your back, neck, or skull. Many grow in the bottom of your spine or at the base of your skull. From there, they can spread to other organs, like your lungs. But they usually grow slowly. Because they're close to important areas like the brain and spinal cord, they need to be treated very carefully. In the womb, a baby has a thin bar called a notochord that runs along his back. This bar supports the bones of the spine as they grow. The notochord disappears before the baby is born. In a small number of people, some of the notochord cells are left behind in the spine and skull. Doctors believe chordoma starts because of a change in the gene that carries instructions for making a protein that helps the spine form. This change causes notochord cells that are left in the brain or spinal cord to divide too quickly. This change usually happens randomly -- no one in your family has to have chordoma for you to get it. But it can run in families in rare instances. Chordomas can press on nerves in your spine or brain. This can cause pain, numbness, or weakness. Your symptoms depend on where the cancer is and how big it is. Chordoma in the skull causes symptoms like: Abnormal eye movements Changes to your voice or speech Double vision Headache Loss of feeling and movement in your face Neck pain Trouble swallowing Chordoma of the spine causes symptoms like: Loss of control over your bowels Lump in the lower part of your back Numbness, tingling, or weakness in your arms or legs Pain in your lower back Problems controlling your bladder Sometimes, chordomas in the brain can block the flow of fluid there and in the spine. The fluid can build up and put pressure on the brain. This is called hydrocephalus. Your doctor can do imaging tests to see where the cancer is inside your body and how big it's grown. These include: X-ray: Low doses of radiation are used to make images of your brain or spinal cord. CT (computed tomography) scan: X-rays are taken from several different angles and put together to make detailed pictures of the affected area. MRI (magnetic resonance imaging): Powerful magnets and radio waves are used to make pictures of organs and other structures inside your body. A biopsy is the only test that can confirm you have chordoma. Your doctor will use a needle to take a small sample of cells from the tumor. A specialist will look at the cells under a microscope to see what kind of tumor you have. Your doctor might also do a blood test, a CT scan of your lungs, or a bone scan to see if the tumor has spread. Your treatment will depend on: Your age Your health Size of the tumor Where the tumor is Often, doctors remove the tumor with surgery. Taking out as much of the tumor as possible and some of the tissue around it can stop it from coming back. Sometimes surgeons can't remove the whole tumor because they might damage healthy cells in your brain or spine. Radiation -- high energy X-rays -- can kill any cancer cells that are left behind after surgery. This lowers the chance that the cancer will return. Still, chordoma often comes back after treatment. During the first year after your surgery, your doctor will check you with an MRI about once every 3 months to make sure it hasn't. If it does come back, you might need another surgery. Researchers are studying several new treatments for chordoma. They test these in clinical trials to see if they're safe and if they work. These are often a way for people to try a new therapy that isn't available to everyone. Your doctor can tell you if there's a trial that might be a good fit for you.