What Is Osteosarcoma?

Osteosarcoma is a rare type of bone cancer that typically affects the long bones in the body, such as those in the arms and legs.

The most common affected areas are the femur (thigh), tibia (shin), and humerus (upper arm) bones. The cancerous cells often develop near the ends of the bones.

Although this cancer can occur in young children and older adults, it most often affects teenagers and young adults. The average age at the time of diagnosis is 15 years old, and approximately 75% of osteosarcoma patients are under 25 years old.

The age of onset is thought to be related to the growth spurts that adolescents experience. If caught early before osteosarcoma metastasizes (spreads), there is a 70% survival rate for osteosarcoma.

In this article, you will learn more about osteosarcoma, including signs and symptoms to watch for, how the cancer is diagnosed, and what treatment options are available.

Symptoms

The most common symptom of osteosarcoma is bone pain at the site of the tumor, which often develops around the knee or the upper arm. The pain may worsen at night and after physical activity. Additional symptoms of osteosarcoma include the following:

• Swelling and redness at the site of the tumor
• Unexplained fever
• Increased pain when lifting the arms
• Increased pain with movement in the legs
• Bone fractures or breaks after minimal movement
• A warm lump that can be felt through the skin
• Limited movement if the condition is in the joints
• Limping if the condition is in the legs

Causes and Risk Factors

There is no known cause of osteosarcoma, but there are a number of risk factors that may increase your chances of developing the disease, including the following:

• Genetics: While the majority of osteosarcoma cases are sporadic, some cases are related to a rare gene mutation called RB1 that also causes hereditary retinoblastoma, a rare eye cancer in children.
• Rapid growth: The risk of osteosarcoma is highest when an adolescent child is going through a growth spurt. This suggests a link between rapid bone growth and tumor formation.
• Radiation: Exposure to high doses of radiation—such as those used to treat other forms of cancer—increase the risk of developing osteosarcoma in the area of exposure. A tumor typically takes a few years to appear after radiation. Lower doses of radiation used in imaging tests like X-rays and computed tomography (CT) scans seem to pose less risk.

 Diagnosis

If your doctor suspects you have osteosarcoma, he or she will first ask questions about your symptoms, your health history, and your family health history. The doctor will also do a thorough physical examination to look for lumps near the bones and any other indicators of irregular growths.

Before making a diagnosis, your doctor will likely recommend you for more tests to confirm the presence of cancer and see if cancer has spread into other areas of the body. These tests may include the following:

• Blood tests: Your doctor will ask for a complete blood count panel (CBC) and comprehensive metabolic panel (CMP), which can indicate if cancer has spread and how the kidneys and liver are working. There is no blood test that will detect a bone tumor.
• Bone X-ray: This is often the first test done, as it can reveal abnormal growth in the bones.
• Bone scan: During this imaging test, a small amount of radioactive dye is injected into your veins to help highlight any areas of bone damage or disease under a scanning machine. This test also may help your doctor stage the disease (detect how advanced it is).
• Biopsy: During this procedure, the doctor will remove a small piece of the tumor to examine and confirm if it is cancerous. Depending on the location of the tumor, one of two types of biopsies may be done. With a core needle biopsy, a doctor uses a hollow needle to remove a small cylinder of the tumor. If the tumor can't be accessed via needle, the doctor may perform a surgical biopsy, in which a piece of the tumor is removed during an operation.
• CT scan: In this imaging test, a computer combines a number of X-ray images to create a 3D cross-sectional view of the interior of the body.
• Positron-emission tomography (PET) scan: This imaging test shows how tissues and organs are working on a cellular level and may be used to help in staging the disease and developing a treatment plan.
• Magnetic resonance imaging (MRI): This imaging test uses radio waves, a large magnet, and a computer to create clear high-resolution images of the internal structures of the body. It's especially helpful in seeing soft tissue areas like the brain, muscles, and tendons. An MRI can give a more detailed view of the bone marrow and soft tissues around the affected area, so it is typically ordered to get a more detailed picture of the extent of the tumor's size and growth.

Treatment

If you or a loved one are diagnosed with osteosarcoma, a team of bone cancer specialists will work with you to develop a treatment plan that optimizes your chance of survival. Depending on the size of the tumor and whether the cancer has spread, treatment options may include the following:

• Surgery: This operation usually requires a specialized surgeon, whose main goal is to remove all of the cancer. When possible, the surgeon will remove the tumor and some of the tissue surrounding the area, while leaving the affected limb intact. In some cases, such as if the tumor is very large or if it extends to the nerves or blood vessels, amputation may be necessary.
• Chemotherapy: Medicine that is injected into the veins or taken by mouth works to kill cancer cells throughout the body. Chemotherapy is sometimes used before surgery to decrease the size of the tumor and make surgery easier. Chemotherapy may also be used after surgery to reduce the risk of cancer returning.
• Radiation: This treatment uses high-energy rays to kill cancer cells. However, osteosarcoma cells are not easily killed by radiation, so it is not commonly used to treat this type of cancer.
• Targeted therapy drugs: These newer non-chemo drugs target specific parts of tumor cells, which blocks them from growing. While some targeted therapy drugs have been approved for other bone cancers, the Food and Drug Administration (FDA) has not yet approved them for osteosarcoma treatment. The research is ongoing, and these drugs may be an option if standard chemo is no longer helpful.

 Prognosis

If osteosarcoma has not spread to other parts of the body, especially to the lungs, the survival rate after five years is approximately 70%. If the cancer has spread, the survival rate drops to 30%–50%. Recurrence can happen, typically within 18 months after treatment. The prognosis, or forecast, for osteosarcoma depends on a number of factors, including the following:

• The location and size of the tumor
• The stage of cancer
• Other existing medical conditions
• The overall health of the patient
• Whether the cancer has spread to other areas of the body

Coping

If you or a loved one receives a diagnosis of osteosarcoma, it is natural to feel scared, angry, worried, and upset. During this time, it's important to reach out to friends and family members and build a support system for you to lean on throughout your cancer journey.

The treatment and recovery for this disease can be long and difficult and especially frustrating for young patients. Make a point to seek additional help through a support group or a professional therapist, who can help you navigate the complex emotions that come up throughout treatment and recovery. Maintaining a positive outlook has been shown to improve recovery outcomes.