Osteosarcoma and malignant fibrous histiocytoma (MFH) of the bone are diseases in which malignant (cancer) cells form in bone.
Osteosarcoma usually starts in osteoblasts, which are a type of bone cell that becomes new bone tissue. Osteosarcoma is most common in teenagers. It commonly forms in the ends of the long bones of the body, which include bones of the arms and legs. In children and teenagers, it often forms in the bones near the knee. Rarely, osteosarcoma may be found in soft tissue or organs in the chest or abdomen.
Ewing sarcoma is another kind of bone cancer, but it is not covered in this summary. See the PDQ summary on Ewing Sarcoma Family of Tumors for more information.
Having past treatment with radiation can increase the risk of osteosarcoma.
Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. People who think they may be at risk should discuss this with their doctor. Risk factors for osteosarcoma include the following:
Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
X-ray: An x-ray of the organs and bones inside the body. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI).
A biopsy is done to diagnose osteosarcoma.
Cells and tissues are removed during a biopsy so they can be viewed under a microscope by a pathologist to check for signs of cancer. It is important that the biopsy be done by a surgeon who is an expert in treating cancer of the bone. It is best if that surgeon is also the one who removes the tumor. The biopsy and the surgery to remove the tumor are planned together. The way the biopsy is done affects which type of surgery can be done later.
The type of biopsy that is done will be based on the size of the tumor and where it is in the body. There are three types of biopsy that may be used:
Immunocytochemistry study: A laboratory test in which a substance such as an antibody, dye, or radioisotope is added to a sample of cancer cells to test for certain antigens. This type of study is used to tell the difference between different types of cancer.
Certain factors affect prognosis (chance of recovery) and treatment options.
The prognosis (chance of recovery) is affected by certain factors before and after treatment.
The prognosis of untreated osteosarcoma and MFH depends on the following:
Where the tumor is in the body and whether tumors formed in more than one bone.
The size of the tumor.
Whether the cancer has spread to other parts of the body and where it has spread.
The type of tumor (based on how the cancer cells look under a microscope).