Osteosarcoma Overview

Osteosarcoma (osteogenic sarcoma) is a type of cancer that starts in your bones. In the beginning, the cancer cells appear to be regular bone cells. Then, they create tumors, and those tumors create immature, irregular, diseased bone. It is most often seen in teenagers, with the average age of diagnosis of osteosarcoma being 15.

Osteosarcoma most often affects long bones, such as those in the arms and legs. It usually occurs near the ends of your bones (the metaphyses) and near your knee where the fastest growth is taking place (if you’re a teenager). The bones and areas most often affected include the:

  • Femur (thigh bone) near your knee
  • Tibia (shin bone) near your knee
  • Humerus (upper arm bone) near your shoulder
  • Rarely, in the soft tissues or organs in your abdomen or chest

Other less common locations for osteosarcoma include your:

  • Pelvis
  • Skull
  • Jaw

Osteosarcoma tumors can be categorized as low-grade, intermediate-grade, or high-grade. Low-grade means that your cancer will grow slowly and remain where it began (localized), while high-grade indicates that it will spread quickly and metastasize. (“Metastasize” is the process of cancer spreading to other parts of your body.)

Most osteosarcoma tumors found in children and teenagers are high-grade. The cells of high-grade osteosarcoma don’t look like normal bone under a microscope. There are nine types of high-grade osteosarcomas:

  • Osteoblastic.
  • Chondroblastic.
  • Fibroblastic.
  • Small cell.
  • Telangiectatic.
  • High-grade surface (juxtacortical high-grade).
  • Pagetoid.
  • Extraskeletal.
  • Post-radiation.

There is one type of immediate-grade osteosarcoma:

  • Periosteal (juxtacortical immediate grade.

And, there are two types of low-grade osteosarcomas:

  • Parosteal (juxtacortial low grade).
  • Intramedullary or intraosseous well-differentiated (low-grade central).

Osteosarcoma Symptoms

The most common symptoms of osteosarcoma include:

  • Bone pain or tenderness.
  • A mass or lump (tumor) that is warm and might be felt through your skin.
  • Swelling and redness at the site of your tumor.
  • Increased pain with lifting (if it affects your arm).
  • Limping (if it affects your leg).
  • Limited movement (if it affects a joint).
  • Unexplained fever.
  • Broken bone (sometimes this happens after a simple movement).

Osteosarcoma Causes

The direct cause of osteosarcoma is unknown. However, there are some risk factors, including:

  • Rapid bone growth: The risk of osteosarcoma increases during a child and adolescent’s growth spurts.
  • Exposure to radiation: This might have occurred from treatment for another type of cancer. This can take a few or several years to occur.
  • Genetic factors: Osteosarcoma is one of several types of rare cancers in young people. This may be related to the retinoblastoma gene, which can be associated with eye cancers in young children or with other tumors in children and young adults in which a mutation of the p53 gene is involved.
  • Bone infarction: This happens when there’s a lack of blood supply to your bone tissue. This destroys the cells.

Osteosarcoma Diagnostics

Your healthcare provider will begin with a thorough history and physical examination. They’ll ask about your symptoms and medical history; for example, any prior radiation treatment or whether anyone in your family has certain hereditary conditions. They’ll also look for lumps that may be protruding from bones.

Your healthcare provider might also use certain tests when making the diagnosis. These include:

  • Blood tests: These tests can provide information about blood counts and how your organs (such as your kidneys and liver) are working. There is no blood test to detect the presence of a bone tumor.
  • X-ray: An X-ray will be done to look for abnormal growths in your bones.
  • Computed tomography (CT): CT uses computers to combine many X-ray images into cross-sectional views of the inside of your body. This test is used to look for any tumors in your lungs.
  • Magnetic resonance imaging (MRI): MRI uses a large magnet, radio waves and a computer to create clear images of body parts. This may be ordered for more detailed pictures if an X-ray is not normal.
  • Bone scan: This test uses a small amount of radioactive material injected into your body to identify bone disorders.
  • ET scan: This test uses a special glucose tracer that shows the areas in your body where the glucose uptake is extra high. This tracer is often taken up in high concentrations in cancer cells.
  • Biopsy: This is a procedure in which a piece of tissue from the affected area is removed so that it can be studied for cancer cells. The two most likely types of biopsy your healthcare provider will use are a core needle biopsy or a surgical biopsy.

After your healthcare provider diagnoses osteosarcoma, the next step is to find out if the cancer cells have spread of if they’ve remained localized. This is called “staging.” The cancer can spread through your blood, your lymph system, or tissues. If the cancer enters your lungs, it’s still referred to as osteosarcoma, not lung cancer. 

Osteosarcoma Treatment

The most common forms of treatment for osteosarcoma are:

  • Surgery: During surgery, the tumor and some of the healthy tissue around it will be cut out of the affected bone. In most cases involving the arm or leg, surgery can be done without amputation. This is called limb-salvage surgery. These procedures may be possible in those whose cancer has not spread beyond its original site. Sometimes, artificial implants or bone taken from another part of your body can be used to replace the bone that was removed during surgery. Unfortunately, there are some cases where a section or all of an arm or leg must be amputated. You’ll get a prosthesis (artificial limb) afterwards.
  • Chemotherapy: This is the use of drugs to kill cancer cells. Chemotherapy is given before surgery to shrink the tumor and kill any cancer cells floating around in the blood, and after surgery to catch any cancer cells that might still be in your body. Chemotherapy before surgery is called “neoadjuvant chemotherapy” and typically takes about 10 weeks. Chemotherapy given after surgery to kill any remaining cancer cells is called “adjuvant chemotherapy.” The typical duration of adjuvant chemotherapy for osteosarcoma is an additional 18 weeks.
  • Radiation therapy: Sometimes radiation is used to treat osteosarcoma. This is particularly important in areas where surgery is not possible. There are two types: external radiation therapy and internal radiation therapy. The external kind uses a machine that points radiation at the area of the body that is cancerous. Internal radiation therapy is where the substance is inserted via needle or catheter. For osteosarcoma, some patients are treated with bone-seeking radiopharmaceuticals (samarium or radium) that are taken up by the bone-forming osteosarcoma cancer cells, delivering radiation specifically to the cancer site.
  • Targeted therapy: Targeted therapy is the use of drugs that block certain proteins that are important to cancer cells. These drugs typically don’t harm normal cells as much as chemotherapy or radiation. Kinase inhibitor therapy, mammalian target of rapamycin inhibitors and monoclonal antibody therapy are the most common drugs used.
  • Cryosurgery: Liquid nitrogen is used to freeze and destroy cancer cells.
  • Amputation: Amputation is the surgical removal of a limb. This is rare.
  • Rotationplasty: This procedure is used on tumors of the distal femur, which is the area of the leg just above the knee. The leg is partially amputated, the tumor is removed and then the lower leg is rotated 180 degrees and reattached, using the ankle as a new knee. This converts the above-knee to a below-knee amputation that is more functional and helps fit a prosthesis. Your healthcare provider will discuss the cosmetic side effects if a rotationplasty is an option.