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Medically reviewed by Last updated on Oct 11, 2023.

What is Osteosarcoma?

Harvard Health Publishing

Osteosarcoma is the uncontrolled growth of abnormal cells in bone. Although it is the most common type of bone cancer, it is rare.

Osteosarcoma typically appears as a mass of abnormal bone in an arm or leg, usually near the knee or shoulder. Less often, the tumor develops in the pelvic bones, jaw, or ribs. It rarely develops in the fingers or toes. At the time of diagnosis, 10% to 20% of osteosarcomas have spread (metastasized) to another part of the body, usually the lungs.

More than half of osteosarcomas develop in people between the ages of 10 and 20, usually during a growth spurt. Young people have a higher risk of developing the disease if they have had eye cancer or Li-Fraumeni syndrome.

About one-third of osteosarcomas strike adults between the ages of 40 and 50. The disease is more common in men than women. Adults are at higher risk if they have a history of Paget's disease or radiation therapy for cancer.


Symptoms include persistent pain and swelling in an arm or leg, especially near the knee or shoulder. Pain may occur at rest, and it may even wake the person from sleep. It may be mistaken at first for a sprain or other sports injury, particularly in active teenagers.

There also may be a firm lump on an arm or leg. The lump may be tender.


Because osteosarcoma is very rare, your doctor will ask about your symptoms and check for more common causes of limb pain and swelling, such as sports injuries and arthritis. He or she will examine the painful area, feeling for warmth, swelling, and tenderness, and looking for signs of joint swelling or fluid. You'll be asked about any difficulty moving the limb or using the joint.

The true cause of your symptoms may not be known until your doctor orders an x-ray of the area. Blood tests may be ordered, too. In most cases, the blood tests will be normal, although some patients will have high levels of certain enzymes. However, the x-ray typically shows characteristic abnormalities suggesting cancer.

Once your doctor has x-ray evidence of a bone tumor, he or she will refer you to a major medical center with the facilities, staff, and experience to treat bone cancer. There, you may have a magnetic resonance imaging (MRI) scan of the area to determine how far the tumor has invaded nearby nerves, blood vessels, and joints. You also may have x-rays and a bone scan to see whether the cancer has spread to your lungs, other bones, and other parts of your body.

When these tests are complete, you will have a biopsy to confirm the diagnosis. In a biopsy, a small piece of bone is removed and checked for cancer cells in a laboratory.

Expected Duration

An osteosarcoma will continue to grow until it is treated. If untreated, this cancer can eventually spread to the lungs and to other bones.


Osteosarcoma cannot be prevented.


In most cases, an osteosarcoma is treated using a three-step approach that includes chemotherapy and surgery:

Although most patients can be treated with limb-sparing surgery, this approach is not always possible. If the tumor has invaded critical blood vessels or part of a nearby joint, the limb may need to be amputated.

Given the rarity of osteosarcoma, it's best to seek care from medical experts who regularly treat the disease.

When to To Call a Professional

Call your doctor if you or a family member has persistent or unexplained pain and swelling in a bone or joint.


Between 70% and 90% of osteosarcomas in the limbs can be treated with limb-sparing surgery and chemotherapy; amputation is not necessary. If osteosarcoma affects only one limb, most patients live long lives. However, the long-term prognosis is less favorable if cancer has spread to the lungs.

Additional Information

National Cancer Institute (NCI)

American Cancer Society (ACS)

American Academy of Pediatrics (AAP)

American Society of Clinical Oncology

American Academy of Orthopaedic Surgeons (AAOS)


Learn more about Osteosarcoma

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.