Chordoma, also known as notochordal sarcoma, is a rare type of cancer that develops from the notochord, a tissue in the embryo that helps in the development of the spine. The notochord is usually replaced by vertebrae by the time we are born, but some notochord cells may remain behind. In rare cases, these cells can become cancerous.
The spine is made up of five main areas: cervical, thoracic, lumbar, sacral, and coccyx. The cervical spine encompasses the first seven vertebrae, and is located between the base of the skull (clivus) and the neck. The thoracic spine, or middle back, is made up of 12 vertebrae, and runs from the end of the cervical spine. The lumbar spine, or lower back, is made up of 5 vertebrae, and runs from the bottom of the thoracic spine down to the sacrum. The sacrum is made up of five vertebrae, and forms a triangle to connect to the hips. After the sacrum is the coccyx, or tailbone, which is made up of four vertebrae.
Most chordomas develop in the sacrum, and are known as sacral tumours. Less commonly, it develops at the top of the cervical spine in the clivus, and are known as clival tumours. In rare cases, they can develop in the mobile spine, which is made up of the cervical, thoracic, and lumbar vertebrae.
Chordomas are more commonly diagnosed in males, and are generally diagnosed between the ages of 40-60. However, anyone can develop this disease.
Types of Chordomas
There are three primary types of chordoma, which are categorised by their cellular appearance under the microscope.
Conventional Chordoma
Conventional chordomas, also known as classic chordomas, are the most common subtype of this disease. They are categorised by ‘bubbly’ appearing cells, and the expression of the brachyury protein, which is responsible for regulating the activity of other cells. Conventional chordomas are often slow growing, rarely aggressive, and can have a good prognosis.
Chondroid Chordoma
Chondroid chordomas are a subtype of conventional chordomas, and are defined as conventional chordomas with the presence of cartilage cells within the tumour. These types of tumours are often found in the clivus, but can develop in other places. Chondroid chordomas are often slow growing, rarely aggressive, and often has the best prognosis of all chordomas.
Dedifferentiated Chordoma
Dedifferentiated chordomas are a very rare subtype of chordoma. It is characterised by properties of both conventional chordoma cells with brachyury protein and high-grade sarcomas without brachyury protein. Dedifferentiated chordomas tend to me more aggressive than conventional chordomas, are more likely to metastasise, and may not have as good of a prognosis.
Poorly Differentiated Chordoma
Poorly differentiated chordomas are a very rare subtype of chordoma that has only recently been recognised. It is characterised by a genetic mutation, or more specifically, the deletion of the SMARCB1/IN1 (or IN1) protein, which is thought to be a tumour suppressor. Unlike most chordomas, this subtype is more common in children and young adults. These tumours are typically found in patients with a clival or cervical tumour. Poorly differentiated chordomas are generally more aggressive than other subtypes, is more likely to metastasise, and may not have as good of a prognosis.
Treatment
When cancers are detected, they are 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. However, because of how rare chordomas are, there is currently no standard staging and grading system for this disease. Instead of staging and grading, your doctor will recommend a treatment plan based on the following factors:
- Cancer location.
- Whether or not the cancer has metastasised.
- Your age.
- General health.
- Your treatment preferences.
Your doctor may also 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 options for chordomas may include:
- Surgery to remove as much of the tumour as possible (it may be difficult to remove the entire tumour as it may be close to critical structures, such as nerves, blood vessels, and the brain).
- Radiation therapy.
- Targeted therapy.
- Immunotherapy.
- Clinical trials.
- Palliative care.
For more information on the treatment options, please refer to the Rare Cancers Australia treatment options page.
Risk factors
Because of how rare chondromas are, there has been limited research done into the risk factors of this disease. However, it has a potential link to genetic mutations of the brachyury and tuberous sclerosis complex (TSC1 and TSC2) genes.
Early symptoms
The symptoms of a chordoma generally vary based on the location of the tumour.
Symptoms of Chordoma in the Clivus
Symptoms of a chordoma in the clivus may include:
- Headaches.
- Double vision.
- Facial pain.
- Changes in hearing.
- Difficulty swallowing.
- Dizziness.
- Neck pain.
- Changes in facial sensation.
- Changes in the voice and/or speech.
Symptoms of Chordoma in the Spine and Sacrum
Chordomas of the spine and sacrum may appear asymptomatic in the early stages of disease. As the cancer progresses, some of the following symptoms may appear:
- Changes in bowel and/or bladder function.
- Back pain.
- Back aches.
- Numbness and/or tingling in the back.
- Weakness in the arms and/or legs.
- Impotence.
- Changes in mobility.
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 a chordoma, 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), 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(s) of the cancer has been identified, the doctor will perform a biopsy to remove a section of tissue using a needle. The tissue sample will then be analysed for cancer cells. This can be done by a fine needle aspiration (FNA), a core needle biopsy (CNB), a surgical biopsy, or a trocar CT-guided biopsy.
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 chordomas 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
Some references are to overseas websites. There may be references to drugs and clinical trials that are not available here in Australia.