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What is Osteosarcoma?

Osteosarcoma is a type of bone cancer most often seen in children and young adults. It is the most common primary pediatric bone tumor. About 400 children and teens are diagnosed in the United States each year. Osteosarcoma is the 3rd most common cancer in teens.

Osteosarcoma may develop in any bone, but it usually forms in the wide ends of long bones of the leg or arm. It most often begins in immature bone cells (osteoblasts) that form new bone tissue.

The most common places for osteosarcoma to develop are near the knee in the lower part of the thigh bone (femur) or the upper part of the shin (tibia). Another common place for osteosarcoma to develop is in the bone of the upper arm near the shoulder (humerus). It sometimes forms in flat bones such as the pelvis or skull, but this occurs less often. In rare cases, osteosarcoma may be found in soft tissue other than bone.

Osteosarcomas may form inside the bone (central tumors) or on the outer surface of bone (surface tumors). Most pediatric osteosarcomas are centrally located inside the bone.

Risk Factors and Causes of Osteosarcoma

Osteosarcoma typically develops after age 10 and is very rare before the age of 5.

There are certain factors that may increase risk for osteosarcoma.

  • Osteosarcoma occurs slightly more often in males than females.
  • African-American children have a higher risk of osteosarcoma compared to Caucasians.
  • Cancer survivors who were treated with radiation therapy have a higher risk for developing osteosarcoma.
  • Genetic factors may increase risk for osteosarcoma. A small percent of children carry changes or mutations in genes that put them at higher risk for osteosarcoma and other cancers. For this reason, people with hereditary retinoblastoma, a history of multiple cancers, and a strong family history of breast cancer, leukemia, brain tumors, and tumors in bones or soft tissues are at higher risk.
  • Other rare inherited conditions due to specific gene mutations may also increase risk for osteosarcoma. These include Li-Fraumeni syndrome, Rothmund-Thomson syndrome, Bloom syndrome, Werner syndrome, and Diamond-Blackfan anemia.

Signs and Symptoms of Osteosarcoma

Osteosarcoma damages and weakens the bone. Symptoms depend on where the tumor is located. Signs may be hard to notice at first and can be like symptoms of other conditions.

Symptoms of osteosarcoma include:

  • Pain in a bone or joint
  • Problems moving the joint
  • A lump or swelling over a bone
  • Limping or problems walking
  • A bone that breaks (fracture)

Pain may worsen over weeks or months. Pain may cause the child to wake up in the middle of the night. Over-the-counter pain medicines such as ibuprofen or acetaminophen may not adequately relieve pain over time.

Diagnosis of Osteosarcoma

Several types of tests are used to diagnose osteosarcoma. These tests include:

  • A health history, physical exam, and blood tests to learn about symptoms, general health, past illnesses, and risk factors.
  • Imaging tests to look for tumors and help determine other tests that are needed.
    • An X-ray of the entire bone is used to look for “skip” lesions, meaning osteosarcoma has spread from the primary tumor to other parts of the bone.
    • A CT scan of the chest is used to see if osteosarcoma has spread to the lungs.
    • An MRI is used to assess the tumor and assist in planning surgery.
    • Full body imaging using bone scans or PET scans is used to look for spread of osteosarcoma to other areas of bone.
  • A biopsy to make a correct diagnosis. In a biopsy, the doctor removes a small amount of tissue from the tumor. An incisional biopsy or core needle biopsy may be used depending on tumor location. The cells are then examined under a microscope to look for signs of cancer. 
X-ray shows an anterior/posterior (front to back) view of skip lesions from osteosarcoma in a patient's femur.
X-ray shows a lateral, or side view of skip lesions from osteosarcoma in a patient's femur.

For pediatric osteosarcoma patients, X-rays are used to look for skip lesions.

Chest CT of a young patient with osteosarcoma shows signs of metastatic disease
Chest CT of a young patient with osteosarcoma shows signs of metastatic disease
Chest CT of a young patient with osteosarcoma shows signs of metastatic disease
Chest CT of a young patient with osteosarcoma shows signs of metastatic disease

A CT scan of the chest is used to see if osteosarcoma has spread to the lungs.

Staging of Osteosarcoma

Osteosarcoma is usually described as either localized or metastatic. Localized osteosarcoma means that there is a tumor in only one place in the body. Metastatic osteosarcoma means that the cancer has spread to other places, such as the lungs or other bones. The most common place for osteosarcoma to spread is the lungs.

Prognosis for Osteosarcoma

Patients with a single, localized osteosarcoma that can be completely removed with surgery have a 65-70% chance of long term cure. If osteosarcoma has already spread at diagnosis (metastatic osteosarcoma), the chance of survival is about 30%. 

Prognosis depends on several factors:

  • Size and location of the tumor
  • Whether the cancer has spread to other parts of the body
  • The ability of surgery to completely remove the tumor
  • If the cancer is recurrent (has come back)
  • How responsive the tumor is to chemotherapy

Approximately 30% of patients will have recurrence of cancer. This most often occurs as new nodules in the lungs. For those who relapse, certain variables influence prognosis including ability to surgically resect the tumor and when relapse occurs. Patients who have early recurrence within 18 months after diagnosis are usually more difficult to treat than those who have later recurrence. If cancer is treated and comes back, the 10-year post-relapse survival is approximately 17%. The likelihood of survival decreases with further relapse. 

Treatment of Osteosarcoma

Osteosarcoma is usually treated with chemotherapy followed by surgery. Additional treatments such as radiation therapy may be used at times if the tumor is not surgically removable or if any disease is left behind after surgery.

  1. Surgery is used to remove the cancer when possible. A small amount of tissue around the tumor will be removed to make sure that no cancer is left behind. Most osteosarcoma can be treated with limb-sparing surgery. In this surgery, the doctor removes the piece of bone with the tumor and replaces the bone with a metal prosthesis or another piece of bone. If it is not possible to remove the entire tumor with limb-sparing surgery, amputation may be needed.

    Pre-op X-ray of the humerus with osteosarcoma tumor marked and measured.

    Pre-op X-ray of the humerus with osteosarcoma tumor marked and measured.

    X-ray of the humerus following limb-sparing surgery shows prosthesis.

    X-ray of the humerus following limb-sparing surgery shows prosthesis.

    X-ray of the humerus 3 years following limb-sparing surgery.

    X-ray of the humerus 3 years following limb-sparing surgery.

  2. Chemotherapy (“chemo”) is used in addition to surgery to treat osteosarcoma. Chemotherapy is given before surgery in an effort to make the tumor smaller. These medicines kill cancer cells or stop them from growing and making new cancer cells. Often, more than one type of medicine will be used to treat osteosarcoma. Most chemotherapy is given through injections but some chemo may be given by mouth. In addition, chemotherapy is often given after surgery for months to remove any remaining cancer cells and to help keep the tumor from coming back.

    Prior to surgery, patients are treated with a 2-month course of chemotherapy. A three-drug regimen often includes cisplatin, doxorubicin, and high dose methotrexate. After surgery to remove the tumor, additional courses of chemotherapy are given. A typical length of treatment is approximately 8-9 months.

  3. Radiation therapy is not often used to treat osteosarcoma. This type of cancer cell is not easily killed by radiation. However, if the tumor cannot be removed completely by surgery or if tumor cells are left behind after surgery, radiation may be given to try to kill or slow the growth of cancer cells.

  4. Targeted therapies are newer drugs that act on specific targets of cancer cells to stop them from growing. Kinase inhibitors and monoclonal antibodies are being studied in the treatment of bone cancers. Kinase inhibitors act to block a protein that signals cancer cells to grow. Monoclonal antibody therapy uses special proteins that attach to cancer cells to kill the cells or slow cell growth.

Life after Osteosarcoma

Monitoring for recurrence

Patients will receive follow-up care every few months to screen for recurrence for several years after treatment. The medical team will make specific recommendations for frequency and types of tests needed. Screening tests usually include blood tests, CT scans of the lungs, and X-rays of the affected bone.

Patients with certain inherited syndromes or genetic conditions may be at risk for future cancers and need additional follow-up care.

Life after limb-sparing surgery or amputation

Overall, most survivors of osteosarcoma who undergo amputation or limb-sparing surgery do well over time. They report good physical function and quality of life. Follow-up care is important to ensure continued mobility. Patients should have an annual exam to check musculoskeletal function. It is important to make sure that there are no ongoing problems. Uneven limb length, changes in gait, joint issues, or other problems can cause chronic pain or disability. These issues must be identified and properly addressed.

Patients who have undergone amputation should also have an annual exam to maintain the function of their prosthetic limbs. An orthopedic surgeon should evaluate patients with an endoprosthesis (bone graft and/or metal implant) at least once a year. Patients who have had limb-sparing surgery may require additional surgeries for limb lengthening until they reach adult height.

Health after osteosarcoma

Children treated for osteosarcoma are at risk for late effects related to therapy. All survivors should continue to have regular physical checkups and screenings by a primary physician. For general health and disease prevention, survivors should adopt healthy lifestyle and eating habits.

Survivors of bone cancer tend to be less active than the general public. Regular exercise is important to maintain health, fitness, and physical function. This is particularly important for patients who have undergone limb-sparing resection or amputation.

Survivors treated with systemic chemotherapy or radiation should be monitored for acute and late effects of therapy. Potential problems due to treatment may include hearing loss, heart problems, kidney damage, and secondary cancers.

Serious chronic health conditions exist 25 years after diagnosis in approximately 25% of survivors, according to the Childhood Cancer Survivor Study. These conditions include second cancers (increased risk following exposure to radiation), congestive heart failure (exposure to doxorubicin), infertility or complications during pregnancy, and end-stage kidney disease or kidney failure. Regular check ups with a primary care physician can help survivors monitor and manage any late effects.

Reviewed: June 2018