Periosteal osteosarcoma, or PO, is a rare type of bone cancer. It usually forms on the surface of bones of the legs called the tibia and femur. It also can form on the surface of bones in the arms called the ulna and the humerus.

PO is most common in young people between the ages of 15 and 30 years old. PO is rare and makes up less than 6% of all osteosarcoma cases.

We do not know how PO forms. Scientists are always working to understand how cancer forms, but it can be hard to prove. We do know that some genetic conditions are associated with a higher risk of forming PO. These genetic conditions include Li-Fraumeni syndrome, Rothmund-Thompson syndrome, and hereditary retinoblastoma.

It is not known if PO runs in families. However, it is possible for PO to be caused by several genetic conditions, which can be inherited.

Symptoms can occur, but they might not lead to a diagnosis right away because these symptoms are related to many different health conditions. Symptoms include:

• Pain
• Bone fractures
• Swelling

Imaging: If you have symptoms of PO, your doctor will use imaging scans such as x-ray, CT, and MRI to look at where the tumor is and how big it is. They will also check for signs that the tumor has spread to other parts of the body.

Biopsy: To check if the tumor is PO your doctor will do a biopsy, taking a small sample from the tumor with a needle. An expert, called a pathologist, will study cells from the sample under the microscope to see what kind of tumor it is.

Treatment for each patient will be unique. You should go to an expert in PO treatment to decide the best approach for your tumor. You can contact MyPART for help finding experts near you.

Surgery: Surgery is the best option to treat PO. If all of the tumor is removed, there is a good chance PO will not grow back. Sometimes this requires amputation of the limb where the tumor has formed. If some cancer cells are left behind, it’s more likely that the cancer will come back—either in the same spot or in a different part of the body, primarily in the lungs.

Chemotherapy: Chemotherapy is sometimes used in combination with surgery to kill cancer cells that may not have been removed during surgery. Chemotherapy can also be used before surgery.

The estimate of how a disease will affect you in the long term is called prognosis. Every person is different, and prognosis will depend on many factors, such as:

• Where the tumor is in your body
• If the cancer has spread to other parts of your body
• How much of the tumor was taken out during surgery

If you want information on your prognosis, it is important to talk to your doctor.

Doctors estimate PO survival rates by how groups of people with PO have done in the past. Because there are so few PO patients, these rates may not be very accurate. In cases where PO was treated successfully, the 5-year survival rate is over 80%. When PO is already advanced or has spread to other parts of the body, it’s harder to treat, which means the 5-year survival rate is lower.