Osteosarcoma is a type of bone cancer that begins in the cells that form bones. Osteosarcoma is most often found in the long bones — more often the legs, but sometimes the arms — but it can start in any bone. In very rare instances, it occurs in soft tissue outside the bone.

Osteosarcoma tends to occur in teenagers and young adults, but it can also occur in younger children and older adults.

Treatment usually involves chemotherapy, surgery and, sometimes, radiation therapy. Doctors select treatment options based on where the osteosarcoma starts, the size of the cancer, the type and grade of the osteosarcoma, and whether the cancer has spread beyond the bone.

Treatment innovations for osteosarcoma have greatly improved the outlook (prognosis) for this cancer over the years. After completion of treatment, lifelong monitoring is recommended to watch for potential late effects of intense treatments.


Signs and symptoms of osteosarcoma may include, among others:

  • Swelling near a bone
  • Bone or joint pain
  • Bone injury or bone break for no clear reason

When to see a doctor

Make an appointment with your child's doctor if your child has any persistent signs and symptoms that worry you. Osteosarcoma symptoms are similar to many more-common conditions, such as sports injuries, so your doctor may investigate those causes first.


It's not clear what causes osteosarcoma. Doctors know this cancer forms when something goes wrong in one of the cells that are responsible for making new bone.

Osteosarcoma begins when a healthy bone cell develops changes in its DNA. A cell's DNA contains the instructions that tell a cell what to do. The changes tell the cell to start making new bone when it isn't needed. The result is a mass (tumor) of poorly formed bone cells that can invade and destroy healthy body tissue. Cells can break away and spread (metastasize) throughout the body.

Risk factors

These factors increase the risk of osteosarcoma:

  • Previous treatment with radiation therapy
  • Other bone disorders, such as Paget's disease of bone and fibrous dysplasia
  • Certain inherited or genetic conditions, including hereditary retinoblastoma, Bloom syndrome, Li-Fraumeni syndrome, Rothmund-Thomson syndrome and Werner syndrome


Complications of osteosarcoma and its treatment include:

  • Cancer that spreads (metastasizes). Osteosarcoma can spread from where it started to other areas, making treatment and recovery more difficult. Osteosarcoma that spreads most often spreads to the lungs and to other bones.
  • Adapting to limb amputation. Surgery that removes the tumor and spares the limb is used whenever possible. But sometimes it's necessary to remove part of the affected limb in order to remove all of the cancer. Learning to use an artificial limb (prosthesis) will take time, practice and patience. Experts can help you adapt.
  • Long-term treatment side effects. The aggressive chemotherapy needed to control osteosarcoma can cause substantial side effects, both in the short and long term. Your health care team can help you manage the side effects that happen during treatment and provide you with a list of side effects to watch for in the years after treatment.