Who gets osteosarcoma? |
Osteosarcoma is a rare cancer, however it is the most common cancer that originates in the bone in children and adolescents. It accounts for 1% of all cancers diagnosed each year in the United States with approximately 750-900 new cases diagnosed each year. In children, osteosarcoma is most commonly diagnosed between 13-16 years of age during the "growth spurt" and is more common in boys than girls. Common sites for osteosarcoma in children are the femur right above the knee, the tibia right below the knee, or the humerus near the shoulder joint.
In adults, osteosarcomas are usually the result of a prior disease like Paget's disease or a previously benign bone injury. Men are more commonly affected than females and there is a higher risk of it metastasizing to another area of the body. Risk factors for osteosarcoma include previous radiation therapy, congenital diseases such as retinoblastoma gene mutation, bone diseases such as Paget's disease or fibrous dysplasia, and other genetic disorders such as Li-Fraumeni syndrome and Rothmond-Thomson syndrome. |
What are the symptoms of osteosarcoma and how is it diagnosed?
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Pain is the most common symptom, which typically occurs after an injury that took place during recreational activity or sport. Additionally, a soft mass or growth may be felt when examining the area. The bone is not very strong where the osteosarcoma is located and a fracture (break) may occur with only minor injury.
Diagnosis of osteosarcoma begins with an X-Ray of the affected area which shows an abnormal area of bone growth. If osteosarcoma is suspected, additional imaging such as MRI, CT ("cat scan"), and/or a PET scan may be done. Diagnosis is confirmed by a bone biopsy, which should be done by an orthopedic oncologist. A bone biopsy is the only way to know if osteosarcoma is present and if so, what type it is. |
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How is osteosarcoma classified?
Osteosarcoma is classified using The Musculoskeletal Tumor Society (MSTS) staging system. This system classifies the tumors by grade, how big the tumor is at the affected site, and if there are metastases or not. A "grade" of a tumor refers to if the cells appear to be the same as the non-cancerous cells, i.e. "low grade", or if they appear much differently than the normal cells, i.e. "high grade". A low grade osteosarcoma is initially classified as Stage 1 and a high grade osteosarcoma is classified as Stage III.
If the osteosarcoma extends all the way through the bone, which is unfortunately typical in high grade osteosarcomas, then the tumor receives an additional classification of "B" whereas a small osteosarcoma that does not extend through the bone is given a classification of "A". So a low grade osteosarcoma that does not extend through the bone is classified as a Stage IA and a high grade osteosarcoma that is large and extends through the bone is Stage IIB or Stage III depending on one final criteria, metastasis.
Metastasis refers to if the tumor has spread to other bones, tissues, or places in the body. If an osteosarcoma has spread to another location, it is given the classification of Stage III no matter what it's grade or size is. By the same token, even if an osteosarcoma is high grade and large it is not given the classification of Stage III without evidence of metastasis.
If the osteosarcoma extends all the way through the bone, which is unfortunately typical in high grade osteosarcomas, then the tumor receives an additional classification of "B" whereas a small osteosarcoma that does not extend through the bone is given a classification of "A". So a low grade osteosarcoma that does not extend through the bone is classified as a Stage IA and a high grade osteosarcoma that is large and extends through the bone is Stage IIB or Stage III depending on one final criteria, metastasis.
Metastasis refers to if the tumor has spread to other bones, tissues, or places in the body. If an osteosarcoma has spread to another location, it is given the classification of Stage III no matter what it's grade or size is. By the same token, even if an osteosarcoma is high grade and large it is not given the classification of Stage III without evidence of metastasis.
What treatment options are available for osteosarcoma?
The treatment options for osteosarcoma vary depending on the patient, the extent of the disease at the time of diagnosis, and other factors. In general, patients will be evaluated by an orthopedic oncologist to determine if the patient is a good candidate for surgery and if so, what type of surgery. Chemotherapy drugs, i.e. medications designed to help in getting rid of the cancer, are commonly used either pre and post-operatively or post-operatively alone, as both methods are effective. Radiation therapy is used less commonly in most osteosarcoma patients, as it has not shown to be of benefit except in certain rare sub-types of osteosarcoma. In summary, the type of therapy-including surgery- will be a team-based decision the patient makes with their medical team.