Osteosarcoma

Osteosarcoma is the most common of three types of bone cancer. It develops in the new tissue of growing bones usually during adolescence. The other types of bone cancer are chondrosarcoma, which arises in cartilage, and Ewing's sarcoma, which may arise in immature nerve tissue in the bone marrow.

Osteosarcoma is the sixth most common type of cancer in children. It is one of the few types of cancers that begin in the bone and can spread to other parts of the body. Many types of cancer begin elsewhere in the body and spread to the bones.

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Symptoms

Osteosarcoma is marked by:

  • Pain in the bone that is sometimes worse at night or during exercise and isn't helped by pain relievers
  • A lump or swelling in a child's arm or leg that develops up to several weeks after the pain. This usually occurs in the longer bones of the body.
  • An unexplained limp
  • Unexplained bone fractures
  • Fatigue
  • Fever
  • Weight loss
  • Anemia

Causes and Risk Factors

Osteosarcoma is caused by genetic errors that occur during times of intense bone growth. It usually develops from osteoblasts, the cells that make bone grow. As a result, it usually affects teens who are having a growth spurt. People who develop osteosarcoma are typically between the ages of 10 and 25.

Most often, osteosarcoma involves the knee. It usually is found in the growing ends of the bones, the metaphysis.

Boys are more likely to develop osteosarcoma than girls. There is some evidence showing that teens who are taller than average have a greater risk of developing osteosarcoma.

Children who have inherited one of the rare cancer syndromes such as retinoblastoma or Li-Fraumeni also have a higher risk of developing osteosarcoma. Because radiation can trigger genetic mutations, children who have received radiation treatment for cancer have a greater risk of developing osteosarcoma.

There is no evidence that an injury can cause osteosarcoma to develop.

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Diagnosis

Your child's doctor will take a detailed medical and family history and do a physical examination. He or she may also order:

  • A blood test. Bone tumors are often associated with increases levels of certain enzymes in the blood.
  • An X-ray to detect any changes in the bone
  • A computed tomography (CT) scan. This will also help identify the best place to take a sample of bone (a biopsy) for examination under a microscope.
  • A bone biopsy. This can be done either using a hollow needle to take a sample of the bone or by doing surgery under a general anesthesia. After the sample is taken, it will be examined by a specialist (a pathologist), who will determine whether the cells are cancer and, if so, what type of cancer.
  • Magnetic resonance imaging (MRI)

If these tests indicate the presences of osteosarcoma, your doctor will order CT scans of your child's chest as well as a bone scan. More MRI studies may also be ordered. These are needed to show whether the cancer has spread to other parts of the body. In addition, these tests may be repeated during treatment to see how treatment is working and whether the cancer has spread.

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Treatments

Because osteosarcoma can spread, even when a tumor is caught early, treatment focuses on the whole body. Treatment may include:

  • Chemotherapy. This uses chemical to kill or shrink the tumor cells that may have spread. Chemotherapy may be used before or after (or both) surgery. It has both short- and long-term side effects including anemia, an increase risk of infections, abnormal bleeding, destruction of the bone marrow, kidney or liver damage, hearing loss or skin or heart problems.
  • Surgery to remove the bone tumor. This involves removing cancerous cells or tumors and repairing the gap left behind in the bone. The gap is filled by a bone graft, usually from the child's own hipbone (pelvis).
  • Surgery to remove a limb affected by osteosarcoma. Amputation may be the only option if the cancer has spread to nearby nerves and blood vessels. After amputation, it may take a child three to six months to learn to use an artificial arm or leg. In addition, psychological and social rehabilitation may be needed.
  • Surgery to remove tumors in other parts of the body that have spread from the bone tumor.
  • Radiation therapy, which uses high doses of X-rays to kill cancer cells

How effective treatment is depends on several factors:

  • How large the tumor is
  • Whether the cancer spread from the bones to other parts of the body. There is a 60% to 80% survival rate for patients receiving treatment for osteosarcoma that has not spread.
  • Where the tumor is located. Outcomes are generally better if the affected bone is in an arm or leg. When the affected bone is in the ribs, shoulder blades, spine or hipbone, outcomes are not as good.
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