What is Osteosarcoma ?

Osteosarcoma is the most common type of bone cancer that is usually found in the ends of long bones, such as shin, thigh bone and upper arm bone.

Osteosarcoma is a rare form of cancer; in children it accounts for about 15% of childhood cancers diagnosed each year. Osteosarcoma is more common in males, and is generally diagnosed in children, teens and young adults between the ages of 10-30; however, anyone can develop the disease.

About 200 Australians are diagnosed with bone sarcoma each year, and osteosarcoma accounts for roughly 35% of these cases. That means approximately 70 cases of osteosarcoma are diagnosed each year.

Types of Osteosarcomas

There are three primary types of osteosarcomas, which are classified by how the cancer cells look under the microscope.

High-grade Osteosarcoma

High-grade osteosarcomas are the most common subtype of this disease and are the most aggressive. The cells analysed under the microscope do not look like normal bone, and many cancer cells are seen dividing into new cells. Some common types of high-grade osteosarcomas include:

Osteoblastic.
Chondroblastic.
Fibroblastic.
Small cell.
Telangiectatic.
Juxtacortical high-grade.

Intermediate-grade Osteosarcoma

Intermediate-grade osteosarcomas are uncommon and are often treated the same as low-grade osteosarcomas. These tumours are defined by being not as extensive as high-grade tumours, but more advanced than low-grade tumours. The most notable type of intermediate osteosarcoma is juxtacortical intermediate-grade osteosarcoma.

Low-grade Osteosarcoma

Low-grade osteosarcomas are the slowest growing subtype of osteosarcoma. The cells analysed under the microscope mostly resemble normal bone cells, with few replicating cancer cells observed. The most common types of low-grade osteosarcomas include:

Juxtacortical low-grade.
Intramedullary or intraosseous well differentiated (low-grade central).

Risk Factors

While causes of most bone sarcomas are unknown, there are several risk factors.

Previous radiotherapy, particularly for people who received high doses at a young age.
Other bone conditions such as Paget’s disease of the bone, fibrous dysplasia or multiple enchondromas.
Genetic factors such as inherited conditions like Li-Fraumeni syndrome, and a strong family history of certain cancers.

Symptoms

The most common symptom of bone sarcoma is a pain in the bones and joints, the pain may be worse at night or during physical activity.

Swelling over the affected part of the bone
Stiffness or tenderness in the bone
Problems with movement, such as an unexplained limp
Loss of feeling in the affected limb
A fractured bone
Unexplained weight loss
Fatigue

Most people that have these symptoms do not have bone sarcoma; however, if you have symptoms for more than two weeks, you should see your GP.

Diagnosis

If your GP feels there's a possibility you have cancer, they'll refer you for a number of hospital tests.

Diagnosis for bone sarcoma will usually be made by a health specialist and will be based on your symptoms, a physical examination and the results of:

Scans – X-rays, magnetic resonance imaging (MRI), positron emission tomography (PET) or computed tomography (CT) scans are usually the first of diagnosis.

Bone biopsy – a sample of suspected cancerous tissue is removed, using a needle or during an operation it can be tested and analysed in a laboratory.

If a diagnosis of a bone sarcoma is confirmed, a pathologist will further examine how likely the cancer is to spread (known as grade), and whether or how far the cancer has spread (known as stage).

Treatment

Osteosarcoma is treated with multimodality (combination) approach including chemotherapy, surgery and/or radiotherapy.

Surgery
- Limb-sparing surgery – taking out and a margin of healthy tissue while still keeping your limb.
- Amputation – sometimes it is not possible to remove all without affecting the arm or leg. In these cases, the health specialist may advise that the only effective treatment will be to remove the limb. However, this is becoming less common with the improvement limb-sparing surgery.

Radiotherapy – uses high-energy radiation to kill cancer cells.

Chemotherapy – the use of anti-cancer drugs to kill cancer cells.

Previous radiotherapy, particularly for people who received high doses at a young age.
Other bone conditions such as Paget’s disease of the bone, fibrous dysplasia or multiple enchondromas.
Genetic factors such as inherited conditions like Li-Fraumeni syndrome, and a strong family history of certain cancers.

Information Sourced From

Rare Cancers Australia - https://www.rarecancers.org.au/knowledgebase/cancer-types/osteosarcoma/

Australia and New Zealand Sarcoma Association - https://www.sarcoma.org.au/pages/about-sarcoma/bone-sarcoma