All About Osteosarcoma
What is a sarcoma?
Sarcoma is a broad term referring to any cancer of the muscle, bone, or connective tissue, such as tendons or cartilage. There are many different subtypes of sarcoma which are classified based on where in the body they arise and how they appear under the microscope. Sarcomas can start in virtually any part of the body. They may occur in adults and in children, and are found in both males and females.
What is an osteosarcoma?
Normal precursor cells exist in the body that should turn into fully developed fibrous tissue, cartilage, or bone over time. However, if these cells begin to multiply and divide abnormally, they can cause tumors. If the cells that begin to divide abnormally were destined to become normal bone, an osteosarcoma arises. 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 for developing an osteosarcoma are in the long bones of the legs and arms.
Who gets osteosarcoma?
Osteosarcoma is a rare tumor, with about 750-900 new cases diagnosed per year in the United States. However, 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 with a second peak in patients 65 years or older.
There is no known increased risk of osteosarcoma based on gender, race, or geography. Prior chemotherapy and radiation therapy are risk factors for developing an 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 cancer. Inherited conditions including hereditary retinoblastoma, Li-Fraumeni syndrome, and Rothmund-Thomson syndrome are associated with spontaneous osteosarcomas. Having a benign disease of the bone such as Paget disease is also a risk factor for older patients for developing an osteosarcoma.
How are osteosarcomas detected?
Most patients diagnosed with an osteosarcoma present to a doctor with complaints of localized pain in the bone which may come and go over time. There can also be a new mass arising from the bone which is painful.
How are osteosarcomas diagnosed?
The workup of an osteosarcoma typically includes a history and physical exam with blood tests to rule out other causes of a painful mass. Imaging is often obtained, 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 evaluate whether the tumor has spread outside the primary site to other areas of the body. Alternatively, a technetium bone scan may be used to determine if the tumor has spread into other bones.
A biopsy is needed to definitively make the diagnosis of osteosarcoma. Often, image-guided needle biopsies can be used. However, if these are not sufficient to make a diagnosis, a surgeon may have to make an excisional biopsy. The biopsy will confirm a diagnosis of osteosarcoma and also give information on the grade, or aggressiveness of the tumor as it appears under the microscope.
How are osteosarcomas staged?
The staging system for osteosarcoma takes into account the size of the primary tumor, the grade of the primary tumor, whether the tumor has spread regionally to lymph nodes, and whether the tumor has spread distantly to other areas of the body.
Stage I: Stage I is divided into IA and IB. Stage IA tumors are low grade and ≤8 centimeters in size without spread to lymph nodes or distant sites. Stage IB tumors are low grade and >8 centimeters or discontinuous in the primary bone site without spread to lymph nodes or distant sites.
Stage II: Stage II is divided into IIA and IIB. Stage IIA tumors are high grade and ≤ 8 centimeters in size without spread to lymph nodes or distant sites. Stage IIB tumors are high grade and >8 centimeters without spread to lymph nodes or distant sites.
Stage III: Stage III tumors are discontinuous tumors in the primary site which are high grade.
Stage IV: Stage IV is divided into stage IVA and IVB. Stage IVA tumors have spread from the primary site to the lungs. Stage IVB tumors have spread from the primary site to the regional lymph nodes or distant sites other than the lungs.
How are osteosarcomas treated?
Given the rarity of sarcoma, these patients are best served at a specialty treatment center. Treatment of sarcoma requires complex multi-modality therapy (surgery, radiation, and chemotherapy). Specific treatment is dependent upon the size and location of the tumor, the grade (aggressiveness) of the tumor, and whether or not it has spread. The following is a general review of current treatments, but specific cases should be discussed with your healthcare team.
Historically, patients with osteosarcoma were treated with surgery alone. However, numerous studies showed that patients treated only with surgery had a high chance of the disease coming back in other areas of the body. Therefore, chemotherapy has been incorporated as a mainstay of treatment for osteosarcoma.
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. However, others exist which can be used depending on the particular patient and treating physician. Chemotherapy is now often given prior to surgery to improve the chance that the tumor can be removed without removing the whole limb.
After the chemotherapy is delivered, the primary tumor in the bone must be addressed to achieve a cure. Most often, the tumors are surgically resected by a surgical oncologist or orthopedic oncologist. The goal of surgery is to completely remove all of the remaining tumor, ideally while preserving the function of the bone. However, 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 evaluated 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.
Different forms of radiation may be given depending on the tumor site and preference of the treating physician (the radiation oncologist). X-ray therapy is most commonly utilized, often with a technique called intensity modulated radiation therapy (IMRT). Proton therapy and particle therapy are available at specialized centers and may protect normal structures especially when high-dose radiotherapy is required for a tumor that cannot be surgically removed.
Clinical trials are extremely important in furthering our knowledge of this disease. It is though 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 a patient has been treated for osteosarcoma, he or she will need to be followed closely by all members of the treating team, which may include a medical oncologist, surgical/ orthopedic oncologist, and radiation oncologist. 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. As patients approach four and five years after their initial therapy, repeat visits and imaging will be less frequent.
In addition to evaluating for disease recurrence, functional assessment of the limb that was treated is an important part of follow-up. For patients who have had a resection of bone but are continuing to grow, repeat surgeries may be required to lengthen the bone. Ongoing physical therapy and rehabilitation may be needed to ensure full range of motion and to optimize long-term use of the limb after treatment.
Fear of recurrence, relationship challenges, 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.
It is important to have a plan for who will provide your cancer-focused follow up care (an oncologist, survivorship doctor or primary care doctor). Talk with your oncology team about developing a survivorship care plan. If you would like to find a survivorship doctor to review your history and provide recommendations, you can contact cancer centers in your area to see if they have a survivor's clinic or search for a clinic on OncoLink's survivorship clinic list.
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.
This website, started by a sarcoma survivor, is based on the mantra "guidance, education, and support". They also maintain a list of specialty centers.
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.
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