All About Osteosarcoma
What is a sarcoma?
Sarcoma refers to any cancer of the muscle, bone, or connective tissues like tendons or cartilage. There are many different subtypes of sarcoma. They are classified based on where in the body they occur and how they look under the microscope. Sarcomas can start in almost any part of the body.
What is osteosarcoma?
The word osteosarcoma comes from 2 smaller words: osteo, meaning “of the bone,” and sarcoma, a general type of cancer as described above. The most common sites of osteosarcoma are in the long bones of the legs and arms. Normal cells called precursor cells should turn into fully developed fibrous tissue, cartilage, or bone over time. But, if these cells begin to multiply and divide abnormally, they can cause tumors. Osteosarcoma forms if the cells that were supposed to become normal bone begin to divide abnormally and form a tumor.
What causes osteosarcoma and am I at risk?
Osteosarcoma is a rare type of cancer. There are about 750-900 new cases diagnosed each year in the United States. It is the most common type of tumor arising from the bone in children and adolescents, accounting for about 60% of bone tumors in this age group. The disease happens most frequently in early adolescence and in people 65 years or older.
There is no known increased risk of osteosarcoma based on gender, race, or geography. If you have had chemotherapy or radiation for another cancer in the past, you may be at a higher risk for osteosarcoma. Osteosarcoma is the most frequent secondary cancer (meaning it is caused by previous treatment) occurring within the first 20 years after radiation for a solid organ cancer.
Some genetic conditions including hereditary retinoblastoma, Li-Fraumeni syndrome, and Rothmund-Thomson syndrome are associated with an increased risk for osteosarcoma. Having a benign disease of the bone such as Paget disease is also a risk factor for older patients for developing an osteosarcoma.
How is osteosarcoma diagnosed?
Most people diagnosed with osteosarcoma have bone pain which may come and go over time. There can also be a new mass arising from the bone which is painful.
The workup of osteosarcoma often includes a history and physical exam with blood tests to rule out other causes of a painful mass. You will likely have several imaging tests, usually starting with an x-ray. More comprehensive imaging such as an MRI of the entire length of the involved bone is helpful to determine the extent of disease. A CT scan of the chest or PET/CT of the whole body is used to see if the tumor has spread outside the primary site to other areas of the body. A technetium bone scan may be used to determine if the tumor has spread into other bones.
A biopsy is needed to diagnose an osteosarcoma. Often, image-guided needle biopsies can be used. However, if these are not able to make a diagnosis, a surgeon may have to do an excisional biopsy. The biopsy will confirm a diagnosis of osteosarcoma and also give information on the grade of the tumor (how it appears under a microscope)
How is osteosarcoma staged?
Most tumor types are staged using a system developed by experts. This has been hard to do for osteosarcoma given the number of different types and the varying locations. The most widely used system has been developed by the American Joint Committee on Cancer (AJCC) (8th edition). The system incorporates tumor size, histologic grade (how different the cells look under the microscope when compared to normal cells) and spread to lymph nodes or other body sites in determining the stage. The "T stage" represents the extent of the primary tumor itself. The "N stage" represents the degree of involvement of the lymph nodes. The "M stage" represents whether or not there is spread of the cancer to distant parts of the body. Osteosarcoma staging also includes histologic grade, “G” which describes how the cells look under a microscope. The “G” is determined by three different factors, cell differentiation, mitotic count and tumor necrosis. The T, N, M, and G ratings are combined to assign a stage, from I (one) denoting more limited disease to IV (four) denoting more advanced disease.
The staging system is very complex. The entire staging system is outlined in the appendix of this article. Though complicated, the staging system helps healthcare providers determine the extent of the cancer, and in turn, make treatment decisions for a patient's cancer. The stage of cancer, or extent of disease, is based on information gathered through the various tests done as the diagnosis and workup of the cancer is being performed.
How is osteosarcoma treated?
Patients should have treatment at a specialty treatment center that works with patients with osteosarcoma. Treatment of osteosarcoma requires complex multi-modality therapy (surgery, radiation, and chemotherapy). Specific treatment depends upon the size and location of the tumor, the grade (aggressiveness) of the tumor, and whether or not it has spread.
In the past, patients with osteosarcoma were treated with surgery alone. Studies have shown that patients treated only with surgery have a high chance of the disease coming back in other areas of the body. Most often, the tumors are surgically resected by a surgical oncologist or orthopedic oncologist. The goal of surgery is to remove all of the remaining tumor while maintaining the function of the bone. There are some tumors that can only be partially removed. If the surgeon is worried that there is residual disease, or if there is evidence of microscopic disease left behind when the tumor is looked at under the microscope, post-operative radiation will likely be recommended. If the tumor cannot be removed at all safely, high dose radiation alone can be considered.
To help reduce the risk of recurrence, chemotherapy and radiation are also used in the treatment of osteosarcoma. These treatments may be given before or after surgery, depending on tumor size and location. Patients are generally treated with an intensive combination of multiple chemotherapy agents. The physician managing the chemotherapy is termed a “medical oncologist,” or “pediatric oncologist.” A common chemotherapy regimen is methotrexate, doxorubicin, and cisplatin, or “MAP” chemotherapy. Other chemotherapy medications that may be used in the treatment of osteosarcoma include ifosfamide, gemcitabine, cyclophosphamide, etoposide, and carboplatin. Targeted therapies including regorafenib, sorafenib, and everolimus may also be used in the treatment of refractory/relapsed or metastatic osteosarcoma.
There may also be a role for radiation treatment in some patients with osteosarcoma. Different forms of radiation may be given depending on the tumor site and preference of the treating the radiation oncologist. X-ray therapy is most often used, often with a technique called intensity-modulated radiation therapy (IMRT). Proton therapy and particle therapy are available at specialized centers. These types of radiation help protect normal structures especially when high-dose radiotherapy is needed for a tumor that cannot be surgically removed.
Clinical Trials
Clinical trials are extremely important in furthering our knowledge of this disease. It is through clinical trials that we know what we do today, and many exciting new therapies are currently being tested. Talk to your healthcare provider about participating in clinical trials in your area. You can also explore currently open clinical trials using the OncoLink Clinical Trials Matching Service.
Follow Up Care and Survivorship
Once you have completed treated for osteosarcoma, you will need to be followed closely by all members of your treatment team. Patients will be followed very closely for the first few years with frequent physical exams as well as imaging of the primary site and of the lungs to ensure the disease has not returned in either area. Four to five years after initial therapy, repeat visits and imaging will be less frequent. General recommendations for follow-up visits include both orthopedic and oncology exams every 3 months in years 1 and 2 after treatment, every 4 months in year 3, every 6 months in years 4 and 5 and annually after year 5. These exams will likely include blood testing and possible PET/CT (full body) and/or bone scan to monitor for possible recurrence.
Your provider will also want to see how well the limb that was treated is doing. For patients who have had a resection of bone but are continuing to grow, repeat surgeries may be needed to lengthen the bone. Ongoing physical therapy and rehabilitation may be needed to ensure a full range of motion and to optimize long-term use of the limb after treatment.
Fear of recurrence, relationship challenges, the financial impact of cancer treatment, employment issues, and coping strategies are common emotional and practical issues experienced by sarcoma of the bone survivors. Your healthcare team can identify resources for support and management of these practical and emotional challenges faced during and after cancer.
Cancer survivorship is a relatively new focus of oncology care. With nearly 17 million cancer survivors in the US alone, there is a need to help patients transition from active treatment to survivorship. What happens next, how do you get back to normal, what should you know and do to live healthy going forward? A survivorship care plan can be a first step in educating yourself about navigating life after cancer and helping you communicate knowledgeably with your healthcare providers. Create your survivorship care plan today on OncoLink.
Resources for More Information
Sarcoma Foundation of America
The SFA raises money for sarcoma research and aims to raise awareness of sarcoma. The site has information for patients as well.
http://www.curesarcoma.org/
Sarcoma Alliance
This website, started by a sarcoma survivor, is based on the mantra "guidance, education, and support". They also maintain a list of specialty centers.
http://www.sarcomaalliance.org
Bone Tumor.org
A site maintained by Dr. Henry DeGroot, an orthopedic oncologist from the University of Massachusetts Medical School. It provides information on a comprehensive list of types of bone tumors in English and Spanish.
http://www.bonetumor.org/
Appendix: AJCC Complete Osteosarcoma Staging, 8th Edition, 2017:Bone Cancers
Appendicular Skeleton, Trunk, Skull, and Facial Bones
T-Primary Tumor | Description |
|---|---|
TX | Primary tumor cannot be assessed |
T0 | No evidence of primary tumor |
T1 | Tumor ≤ 8 cm in greatest dimension |
T2 | Tumor > 8 cm in greatest dimension |
T3 | Discontinuous tumors in the primary bone site |
Spine
T-Primary Tumor | Description |
|---|---|
TX | Primary tumor cannot be assessed |
T0 | No evidence of primary tumor |
T1 | Tumor confined to one vertebral segment or two adjacent vertebral segments |
T2 | Tumor confined to three adjacent vertebral segments |
T3 | Tumor confined to four or more adjacent vertebral segments, or any nonadjacent vertebral segments |
T4 | Extension into the spinal canal or great vessels |
- T4a - T4b | Extension into the spinal canal Evidence of gross vascular invasion or tumor thrombus in the great vessels |
Pelvis
T-Primary Tumor | Description |
|---|---|
TX | Primary tumor cannot be assessed |
T0 | No evidence of primary tumor |
T1 | Tumor confined to one pelvic segment with no extraosseous extension |
-T1a -T1b | Tumor ≤ 8 cm in greatest dimension Tumor > 8 cm in greatest dimension |
T2 | Tumor confined to one pelvic segment with extraosseous extension or two segments without extraosseous extension |
-T2a -T2b | Tumor ≤ 8 cm in greatest dimension Tumor > 8 cm in greatest dimension |
T3 | Tumor spanning two pelvic segments with extraosseous extension |
-T3a -T3b | Tumor ≤ 8 cm in greatest dimension Tumor > 8 cm in greatest dimension |
T4 | Tumor spanning three pelvic segments or crossing the sacroiliac joint |
-T4a
-T4b | Tumor involves sacroiliac joint and extends medial to the sacral neuroforamen Tumor encasements of external iliac vessels or presence of gross tumor thrombus in major pelvic vessels |
N-Regional Lymph Nodes | Description |
|---|---|
NX | Regional lymph nodes cannot be assessed Because of the rarity of lymph node involvement in bone sarcomas, the designation NX may not be appropriate and cases should be considered N0 unless clinical node involvement is clearly evident. |
N0 | No regional lymph node metastasis |
N1 | Regional lymph node metastasis |
M-Distant Metastasis | Description |
|---|---|
M0 | No distant metastasis |
M1 | Distant metastasis |
-M1a -M1b | Lung Bone or other distant sites |
G-Histologic Grade | Description |
|---|---|
GX | Grade cannot be assessed |
G1 | Well differentiated-Low Grade |
G2 | Moderately differentiated-High Grade |
G3 | Poorly differentiated-High Grade |
Stage Grouping
*there are no AJCC prognostic stage groupings for spine/pelvis
Stage | T | N | M | G |
|---|---|---|---|---|
Stage IA | T1 | N0 | M0 | G1, GX |
Stage IB | T2 T3 | N0 N0 | M0 M0 | G1, GX G1, GX |
Stage IIA | T1 | N0 | M0 | G2, G3 |
Stage IIB | T2 | N0 | M0 | G2, G3 |
Stage III | T3 | N0 | M0 | G2, G3 |
Stage IVA | Any T | N0 | M1a | Any G |
Stage IVB | Any T Any T | N1 Any N | Any M M1b | Any G Any G |
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