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.

Chondrosarcoma is a type of bone cancer that starts in cartilage cells. Cartilage is the smooth connective tissue that protects the ends of bones and lines most joints. Most bones develop from cartilage. And it plays an important role in the growth process. There are many different types of cartilage all over the body. Chondrosarcoma mainly affects the cartilage cells of the thighbone (femur), arm (humerus), or pelvis. Less often, it starts in the knee, ribs, skull, and windpipe (trachea).

Chondrosarcoma is the second most common type of primary bone cancer in adults after osteosarcoma. A primary bone cancer is one that starts from bone cells. It's not the same as cancer that starts in another organ and then spreads to the bone. That's called metastatic cancer to the bone or bone metastasis.

The exact cause of chondrosarcoma is not known. There may be a genetic change that makes some people more likely to have this cancer.

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.

Chondrosarcoma is rare in people younger than age 20. Risk goes up with age with most diagnosed over 50 years of age. It happens almost equally to males and females.

Most often, chondrosarcoma starts in normal cartilage cells. It may also start in a noncancer (benign) bone or cartilage tumor. Here are some of the benign conditions that may be present when chondrosarcoma happens:

• Enchondroma. This is a type of benign bone tumor that starts in cartilage and often affects the hands and feet but can develop in other bones. The cause is unknown.
• Multiple hereditary exostoses (MHE). This is a syndrome passed in families (inherited). It causes many osteochondromas. These are overgrowths of cartilage and bone near the end of the growth plate of long bones in the arms or legs. These bone defects can develop into chondrosarcoma.
• Ollier disease (enchondromatosis). The cause of this rare disease is not known, and it isn't inherited. It is most common in children and young adults. It causes clusters of enchondromas that often affect the hands and feet. It can cause severe bone deformities and fractures. Ollier disease increases the risk of developing chondrosarcoma.
• Maffucci syndrome. This very rare disease is not inherited. It causes many enchondromas that usually affect the hands and feet and benign tumors made up of blood vessels (angiomas). It increases the risk of chondrosarcoma and other kinds of cancer.

Talk with your doctor about your risk factors for chondrosarcoma and what you can do about them.

Symptoms of chondrosarcoma depend on where the tumor is and how big it is. These are the most common symptoms of chondrosarcoma, but they can be different for each person:

• Large lump (mass) on a bone
• Feeling of pressure around the lump
• Pain that gets worse over time
• Weakness and limited movement in a limb or joint
• Local swelling
• Joint stiffness
• Tumors in the pelvis can cause bowel or bladder problems

Many of these 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.

The doctor will ask about your health history and symptoms. A physical exam will be done. You may also need tests, such as:

• Blood tests. These are used to get an idea of your general health and how well your organs are working.
• X-rays. Small doses of radiation are used to make images of internal tissues, bones, and organs. This is often the first test done. It can show bone changes and help the doctor decide if more detailed imaging scans are needed.
• CT scan. X-rays and a computer are used to make detailed 3-D images of the inside of the body. A CT scan shows details of the bones, muscles, fat, and organs.
• MRI. This imaging test uses large magnets, radio waves, and a computer to make detailed images of organs and structures inside the body.
• Positron emission tomography (PET) scan. For this imaging test, radioactive-tagged sugar (glucose) is put into the blood through a vein in the hand or arm. Cells that use the glucose more than normal tissues (such as cancer cells) can be found by a scanning machine.
• Biopsy. Tiny pieces of tissue (called samples) are removed from the tumor for testing. This might be done with a needle or during surgery. The samples are then checked under a microscope. This is done to find out if cancer or other abnormal cells are present.

After a diagnosis of chondrosarcoma, you'll need more tests. These help your doctors learn more about your overall health and the cancer. They can help show if the cancer has grown into nearby areas or spread to other parts of your body. The test results help your doctors decide the best ways to treat the cancer. They're used to find out the stage and grade of the cancer.

The stage tells your doctor how much cancer there is and how far it has spread in your body. The grade is used as part of staging. It gives you an idea of how fast the cancer will grow and spread. These are important things to know when deciding how to treat it.

Stage groupings can have a value of 1 to 4. They are written as Roman numerals I (1), II (2), III (3), or IV (4). The higher the number, the more advanced the cancer is. Letters and numbers can be used after the Roman numeral to give more details.

The grade is a measure of how much the cancer cells look like normal cells. A scale of 1 to 3 is used. Grade 1 cancer cells look a lot like normal cells and tend to grow and spread slowly. Grade 3 cancer cells look very different from normal cells. They grow and spread fast. Grade 2 falls in between. Most chondrosarcomas are grade 1 or 2.

Your doctor will talk with you about what your cancer stage and grade mean for your treatment. Be sure to ask your doctor to explain the details of your cancer to you in a way you can understand.

Treatment will depend on the size of the tumor, where it is, and its grade. It will also depend on your symptoms, age, general health, and preferences. Other things to think about are if the cancer can be removed with surgery and how your body will look and work after treatment.

The goal for treatment of chondrosarcoma is to remove the tumor and reduce the chance that it will return. Close follow-up with your doctor is needed. And tests will be done during treatment to see how well it's working.

Your treatment choices may include:

• Surgery. This is the most common treatment for chondrosarcoma. It's done to remove the tumor and a rim (margin) of healthy tissue around it. If the tumor is on an arm or leg, the surgeon will try to save the limb. In some cases, amputation might be needed.
• Radiation therapy. Radiation might be used after surgery to kill any cancer cells that may be left behind when the tumor was removed. It might also be used when surgery can't be done or if the tumor comes back after treatment.
• Chemotherapy and targeted therapy. While seldom used, it may be needed if the cancer has spread to other parts of the body. It might also be used to treat some high-grade chondrosarcomas.

Talk with your doctors about your treatment choices. Ask if there are clinical research trials that may be a choice for you. Make a list of questions. Think about the benefits and possible side effects of each choice. Discuss your concerns with your doctor before making a decision.

Surgery itself is linked to side effects like pain, bleeding, and infection. But bone surgery has its own side effects that you will have to manage. Physical therapy is often needed. This treatment helps to regain strength and use of the affected area after surgery.

Cancer treatments, like radiation, can damage normal cells. This can cause side effects like skin sores and vomiting. 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.

• Chondrosarcoma is a type of bone cancer that starts in cartilage cells. Cartilage is the smooth connective tissue that protects the ends of bones and lines most joints.
• Chondrosarcoma is the second most common type of primary bone cancer in adults.
• The exact cause is not known. There may be a genetic change that makes some people more likely to have this cancer.
• Symptoms can include a large mass on the affected bone, and pain that gets worse over time.
• Treatment may include surgery, radiation therapy, or possibly chemotherapy or targeted therapy.

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 and on weekends and holidays.