A chordoma is a very rare form of bone cancer that can start anywhere along the spine from the base of the skull to the lower back. Cancer starts when cells change (mutate) and grow out of control. The changed (abnormal) cells often grow to form a lump or mass called a tumor. Cancer cells can also grow into (invade) nearby areas. They can spread to other parts of the body, too. This is called metastasis.

When a chordoma is at the place where the spine meets the base of the skull, it's called a skull base chordoma. Because the tumor is at the base of the skull, it can affect vital structures. These include the brain, blood vessels, the spinal cord, and nerves, like those that control movement of the face and eyes, and swallowing.

Skull base chordomas are divided into four types:

• Conventional. This is the most common type. It might be called a classic chordoma.
• Chondroid. This type has about the same outlook as conventional chordomas.
• Dedifferentiated. This rare form grows more quickly than the other types. It's also more likely to spread to other parts of the body.
• Poorly differentiated. This subtype tends to grow faster than conventional chordomas. These tumors do not make a protein called INI1.

Experts don't know what causes skull base chordomas. They are rare cancers. Anyone can develop a chordoma at any age. But skull base chordomas are more common in younger people.

A risk factor is anything that may increase your chance of having a disease. The exact cause of someone's cancer may not be known. But risk factors can make it more likely for a person to have cancer. Some risk factors may not be in your control. But others may be things you can change.

There are no known risk factors for skull base chordomas. Studies are being done to learn more about the gene changes found in these cancer cells.

The most common symptoms are caused by the tumor pressing on nearby structures. They are related to pain or changes in nerve function. They can include:

• Headache
• Face or neck pain
• Double vision
• Numbness in the face
• Paralysis of the facial muscles
• Voice changes
• Swallowing problems

Many of these symptoms may be caused by other health problems. Still, it's important to see a doctor if you have these symptoms. Only a doctor can tell if you have cancer.

Your doctor will ask you about your health history and symptoms. A physical exam will be done. You may also have some tests done, such as blood tests and an X-ray or other imaging tests. Imaging scans are needed to diagnose a skull base chordoma. These may include CT or MRI scans.

A biopsy is the only way to know for sure if you have a skull base chordoma. Tiny pieces of tissue are taken out from the tumor and tested for cancer cells. Depending on where the tumor is, a biopsy might not be done until you have surgery to take out the tumor.

Testing, biopsy, and surgery, if needed, should be done by a specialist. This might be a neurologist or a neurosurgeon. It's important to see a team of doctors who have experience diagnosing and treating chordomas.

It's common for a chordoma to be confused with another type of bone tumor called a chondrosarcoma. Both types of tumors start in the same parts of the body. These tumors also look a lot alike. A special kind of MRI called a diffusion MRI can help doctors tell the difference. Sometimes a biopsy and tumor tissue tests may be needed to get the right diagnosis.

Your treatment choices depend on where the skull base chordoma is, how big it is, what your test results are, and what problems it may be causing. The goal of treatment may be to cure you, control the cancer, or help ease problems caused by the cancer. Talk with your health care team about your treatment choices, the goals of treatment, and the possible risks and side effects. Other things to think about are if the cancer can be removed with surgery, how your body will look and work after treatment, and your overall health.

The main treatment for a skull base chordoma is surgery to remove as much of the tumor as possible. A wide rim (margin) of healthy tissue around the tumor is also removed. This is done to lower the risk that the tumor will come back later. Surgery can lead to some side effects, but it offers the best chance for long-term survival. You and your health care team should weigh the risks and benefits before the surgery.

Once the surgery is done, radiation therapy is used to kill any remaining nearby tumor cells. Proton beam radiation is often used. It can focus on the place where the tumor was without harming nearby organs and structures. Other forms of radiation can also be used. Sometimes radiation is given before and after surgery. When given before surgery, it can help shrink the tumor so it's easier to remove.

Radiation therapy might be the only treatment used if the tumor can't be removed with surgery or you don't want surgery because of the risks involved.

Chemotherapy doesn't work well in treating skull base chordomas. At this time, there are no chemo medicines approved for treating chordomas. But clinical trials are being done to look for medicines that can help.

Cancer treatment, such as surgery and radiation, can damage normal, healthy cells. This can cause side effects like hair loss, mouth sores, and headaches. It can also cause changes in how well you can hear, smell, or taste. Surgery can put you at risk for infection and cause pain as you heal. Talk with your doctor about side effects linked with your treatment. There are often ways to manage them. There may be things you can do and medicines you can take to help prevent or control many treatment side effects.

Skull base chordomas are rare. Experts don't know how to prevent them.

A skull base chordoma is cancer (malignant) and can be life-threatening. It's often tough to treat. And even with treatment, these tumors often come back in the same area.

Outcomes from chordoma treatment have improved in recent decades. It's important to be treated by a medical team that has experience with these tumors. It's also a good idea to address possible end-of-life issues as part of a skull base chordoma management plan.

Your doctor will talk with you about when to call. You may be told to call if any of the following occur:

• New symptoms or symptoms that get worse
• Signs of an infection, such as a fever
• Side effects of treatment that affect your daily function or don't get better with treatment

Ask your doctor what signs to watch for and when to call. Know how to get help after office hours and on weekends and holidays.

• A chordoma is a form of bone cancer that starts along the spine. When it occurs at the base of the skull, it's called a skull base chordoma.
• It often affects vital structures, such as the nerves that control movement of the face and eyes, and swallowing.
• The main treatment is surgery to remove as much of the tumor as possible.
• Once the surgery is done, radiation therapy is often used to kill any remaining tumor cells.
• Even with treatment, these tumors often come back in the same area. Long-term follow-up is needed to watch for signs that the cancer has come back.

Tips to help you get the most from a visit to your doctor:

• Know the reason for your visit and what you want to happen.
• Before your visit, write down questions you want answered.
• Bring someone with you to help you ask questions and remember what your doctor tells you.
• At the visit, write down the name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new instructions your doctor gives you.
• Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
• Ask if your condition can be treated in other ways.
• Know why a test or procedure is recommended and what the results could mean.
• Know what to expect if you do not take the medicine or have the test or procedure.
• If you have a follow-up appointment, write down the date, time, and purpose for that visit.
• Know how you can contact your doctor if you have questions, especially after office hours or on weekends.