Chondrosarcoma is a group of bone cancers that start in the cartilage. Cartilage is a connective tissue found in many parts of your body, such as in your joints where your bones meet.

About 1 in 200,000 people in the United States develop chondrosarcoma each year.

Chondrosarcoma tends to grow slowly and usually has a good outlook, but aggressive forms can spread to distant organs, such as your liver. Catching the cancer before it spreads gives you the best chance of successful treatment.

Read on to learn more about chondrosarcoma, including symptoms, diagnosis, and treatment.

Chondrosarcoma makes up about 20 percent of all bone cancers and is the third most common bone cancer after myeloma and osteosarcoma.

This type of cancer develops in hyaline cartilage that’s found in many areas, such as in the inner cavity and at the ends of your long bones. It’s classified as conventional or secondary chondrosarcoma depending on how it develops.

  • Conventional chondrosarcoma develops in normal bone and makes up approximately 90 percent of all chondrosarcomas.
  • Secondary chondrosarcoma develops from preexisting tumors called enchondromas or osteochondromas and accounts for 10 percent of all chondrosarcomas.

Chondrosarcoma is further classified as central if it develops in the cartilage that lines the central cavity of a bone, or peripheral if it develops on the outer surface. Conventional chondrosarcoma is almost always central.

What are long bones?

The bones in your body come in a variety of sizes and shapes. Bones that are longer than they are wide are called long bones. They can be found in the thigh, leg, arm, forearm, and fingers.

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Symptoms of chondrosarcoma depend on where the cancer develops and how large it is. The most common places that develop chondrosarcoma are your pelvis or the long bones in your arms and legs.

Symptoms may include:

  • a large lump on a bone
  • progressively worsening pain
  • pressure around the lump
  • swelling around the lump
  • joint stiffness
  • joint weakness or limited movement
  • bowel or bladder problems, if a tumor develops in your pelvis

Although rare, neurological symptoms can develop if the cancer forms in your skull and causes pressure on your brain and cranial nerves. Double vision and headaches are the most reported symptoms.

It’s not known exactly why chondrosarcoma develops, but it’s thought that genetic factors may play a role. Certain atypical genetic characteristics have been detected in the DNA of some chondrosarcomas on chromosomes 9, 10, 13, and 17.

Risk factors for developing chondrosarcoma include:

  • Older age. Most people with chondrosarcoma are over the age of 50 when they receive a diagnosis.
  • Sex. Men are slightly more likely to develop chondrosarcoma than women.
  • Benign bone tumors. Noncancerous bone tumors called enchondromas and osteochondromas can sometimes turn into chondrosarcoma.
  • Multiple exostosis. Multiple exostosis is a genetic condition that causes many noncancerous osteochondromas. It’s often caused by mutations in the genes EXT1 or EXT2.

If a doctor suspects that you may have a bone cancer, they’ll likely order imaging tests to look for a tumor. X-rays are often the first imaging test performed. If something atypical appears on your X-ray, your doctor may order other imaging tests, such as:

  • Computed tomography (CT) scan. A CT scan uses rotating X-rays and a computer to produce 3D images that provide more detail than a traditional X-ray.
  • Magnetic resonance imaging (MRI). An MRI uses radio waves and magnets to create detailed images of your bones and other tissues. MRIs can help doctors see if the cancer has grown into your soft tissues.
  • Positron emission tomography (PET) scan. During a PET scan, you receive a radioactive sugar tracer, typically via injection. The scan can then see where this tracer ends up to help identify cancer cells that use sugar at a faster rate than healthy cells.

A biopsy is needed to confirm your diagnosis. A biopsy involves the removal of a small section of the tumor for lab analysis. A specialist will examine the tissue under a microscope to confirm your diagnosis.

They’ll also classify your cancer from grade 1 to 3 based on how quickly it’s likely to spread based on its cellular features.

Grade 1 chondrosarcoma is considered the least aggressive, while grade 3 is the most aggressive.

Surgery is the primary treatment for chondrosarcoma. Chemotherapy and radiation are generally not effective for conventional chondrosarcoma.

If the cancer is low grade, it can be treated with a technique called intralesional curettage, which involves shaving the cancerous cells away without removing any bone.

Large tumors are usually treated with a surgical technique called wide en bloc excision, where the cancer and surrounding tissue are removed together. In a 2021 case study, researchers describe using this technique to remove a chondrosarcoma tumor that was 3 kilograms (6.6 pounds).

If the cancer is very large and has grown into nerves or blood vessels, amputation of a limb may be necessary.

Radiation therapy is sometimes used to destroy cancer cells that may not have been removed completely after surgery. It’s also sometimes used to treat recurrent chondrosarcoma.

Chemotherapy may be used if cancer has spread to other parts of your body.

Clinical trials are continuing to look at drugs that may help treat chondrosarcoma, including targeted therapies and immunotherapies.

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Most people with chondrosarcoma have a good outlook, but about 6 percent of people have cancer that has spread to distant organs at the time of diagnosis.

Low grade cancers have a good outlook with a 5-year survival rate of around 83 percent. High grade cancers have a less favorable outlook. The 5-year survival is 53 percent for grades 2 and 3.

The difference in outlook is largely due to the chances of the cancer spreading to distant organs:

  • Grade 1 tumors have about a 10 percent chance of spreading.
  • Grade 2 tumors have a 10 to 50 percent chance of spreading.
  • Grade 3 tumors have a 50 to 70 percent chance of spreading.

Where the chondrosarcoma is located also affects outlook. Tumors of the pelvis tend to be the most aggressive and are associated with the lowest survival rate.

Even if surgery is successful, chondrosarcoma often negatively affects a person’s quality of life and physical function. Your surgical team can give you an idea of what to expect after treatment and how you can minimize your chances of complications.

Chondrosarcoma is a group of cancers that start in your cartilage. It most commonly occurs in your long bones or your pelvis.

Most people who receive a diagnosis of chondrosarcoma have low grade cancer that tends to grow slowly and has a good outlook.

It can be difficult to spot the symptoms of chondrosarcoma in the early stages, but it’s important to see your doctor as soon as possible if you notice any concerning symptoms, like a lump or pain in your bone without a known cause.

Catching the cancer before it spreads gives you the best chance of survival.