Osteosarcoma is the most common type of bone cancer that is usually found in the ends of long bones, such as the shin, femur (thigh bone) and humerus (upper arm bone). It is a type of sarcoma, which is a cancer that develops from the cells in bone and/or soft tissue.
Osteosarcoma is more common in males, and is generally diagnosed in children, teens, and young adults. However, anyone can develop this disease.
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).
Treatment
If an osteosarcoma is detected, it will be staged and graded based on size, metastasis (whether the cancer has spread to other parts of the body) and how the cancer cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you.
Cancers can be staged using the TNM staging system:
- T (tumour) indicates the size and depth of the tumour.
- N (nodes) indicates whether the cancer has spread to nearby lymph nodes.
- M (metastasis) indicates whether the cancer has spread to other parts of the body.
This system can also be used in combination with a numerical value, from stage 0-IV:
- Stage 0: this stage describes cancer cells in the place of origin (or ‘in situ’) that have not spread to nearby tissue.
- Stage I: cancer cells have begun to spread to nearby tissue. It is not deeply embedded into nearby tissue and had not spread to lymph nodes. This stage is also known as early-stage cancer.
- Stage II: cancer cells have grown deeper into nearby tissue. Lymph nodes may or may not be affected. This is also known as localised cancer.
- Stage III: the cancer has become larger and has grown deeper into nearby tissue. Lymph nodes are generally affected at this stage. This is also known as localised cancer.
- Stage IV: the cancer has spread to other tissues and organs in the body. This is also known as advanced or metastatic cancer.
Cancers can also be graded based on the rate of growth and how likely they are to spread:
- Grade I: cancer cells present as slightly abnormal and are usually slow growing. This is also known as a low-grade tumour.
- Grade II: cancer cells present as abnormal and grow faster than grade-I tumours. This is also known as an intermediate-grade tumour.
- Grade III: cancer cells present as very abnormal and grow quickly. This is also known as a high-grade tumour.
Once your tumour has been staged and graded, your doctor may recommend genetic testing, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you.
Treatment is dependent on several factors, including location, stage of disease and overall health.
Treatment options for osteosarcoma may include:
- Surgery, potentially including:
- Limb-sparing surgery (surgery to remove the cancer only and salvage the limb).
- Amputation (removal of part or all of the affected limb).
- Rotationplasty (for osteosarcomas of the knee – the middle portion of the leg is removed, and the lower leg is reattached to your upper leg and rotated 180 degrees. The ankle joint will function as the new knee and a prosthetic leg will act as your lower leg).
- Bone graft (a portion of bone from another part of the body or another person is used to replace the bone lost to cancer).
- Chemotherapy.
- Radiation therapy.
- Clinical trials.
- Palliative care.
For more information on the treatment options, please refer to the Rare Cancers Australia Treatment Options page.
Risk factors
While the cause of osteosarcomas remain unknown, the following factors may increase your risk of developing the disease:
- Teenage growth spurts.
- Being tall for specific age.
- Previous radiation treatment.
- Certain bone diseases, such as:
- Paget disease of the bone.
- Hereditary multiple osteochondromas.
- Fibrous dysplasia.
- Inherited disorders, such as:
- Li-Fraumeni syndrome.
- Rothmund-Thompson syndrome.
- Hereditary retinoblastoma.
- Bloom syndrome.
- Werner syndrome.
- Diamond-Blackfan anaemia.
Not everyone with these risk factors will develop the disease, and some people who have the disease may have none of these risk factors. See your general practitioner (GP) if you are concerned.
Early symptoms
The symptoms of osteosarcoma may include:
- Pain in affected bone.
- Swelling in affected area.
- Easily broken bones.
- Increased pain with movement, activity or lifting.
- Decreased movement of affected limb.
Not everyone with the symptoms above will have cancer, but see your general practitioner (GP) if you are concerned.
Diagnosis/diagnosing
If your doctor suspects you have an osteosarcoma, they may order the following tests to confirm the diagnosis and refer you to a specialist for treatment.
Physical examination
Your doctor will collect your overall medical history, as well as your current symptoms. Following this, they may examine your body to check for any abnormalities.
Imaging & blood tests
The doctor will take images of your body using magnetic resonance imaging (MRI), a computed tomography scan (CT scan), x-rays, bone scan and/or positron emission tomography (PET scan), depending on where it is suspected the cancer is. The doctor may also look at other parts of the body and looks for signs of metastasis. Additionally, a blood test may be taken to assess your overall health and help guide treatment decisions.
Biopsy
Once the location of the cancer has been identified, the doctor will perform a biopsy to remove a section of tissue using a needle. This is often done by a fine needle aspiration (FNA), a core needle biopsy (CNB), or by surgical means (excisional or incisional biopsy). These samples will then be analysed for cancer cells.
Prognosis (Certain factors affect the prognosis and treatment options)
While it is not possible to predict the exact course of the disease, your doctor may be able to give you a general idea based on the rate and depth of tumour growth, susceptibility to treatment, age, overall fitness, and medical history. Generally, early-stage osteosarcomas have a better prognosis and survival rates. However, if the cancer is advanced and has spread, the prognosis may not be as good and there may be a higher risk of cancer recurrence. It is very important to discuss your individual circumstances with your doctor to better understand your prognosis.
References