Chordoma

What is Chordoma?

A chordoma is a type of slow-growing tumor that, despite developing at a gradual pace, can cause local damage and behave aggressively. This tumor falls under the broader family of tumors known as sarcomas. Chordomas form from leftover parts of the notochord, a structure present during our early development, and they usually grow along the spine’s centerline, sitting in front of the spinal cord.

The location of chordomas can vary: half of them usually develop at the base of the spine (the sacrum), around one-third appear at the base of the skull, and the rest can be found in the spine’s moving parts – most often in the second vertebrae in the neck, followed by the lower back and upper back spine.

The chances of surviving five years after being diagnosed with a chordoma are roughly 50%. The typical treatment plan for chordomas involves a type of surgery known as en bloc resection to remove the tumor, followed by a specialized form of high-dose radiation therapy, such as proton beam radiation.

What Causes Chordoma?

Chordomas are tumors that develop from a structure called the notochord. The notochord is an important part of an embryo. It gives instructions to other tissues on how to organize and develop. As humans grow, the notochord shrinks to form a part of the spine known as the nucleus pulposus.

Several genes are believed to play a part in the formation of chordomas. These include the brachyury gene, the mTOR signaling pathway, the PTEN gene, INI-1, and the PDGFR-beta. However, no specific genetic marker has been identified yet as the main cause of chordomas.

It’s worth mentioning that there have been few cases of chordomas running in families. So, while we know that genes play a role in these tumors, there’s still much to learn about how this disease develops.

Risk Factors and Frequency for Chordoma

Chordomas are typically found in people aged 40 to 60, but they can also occur in children and the elderly. It’s generally more common in males, with a rate of two males diagnosed for every female. Each year, one in a million people are newly diagnosed with this condition.

• Chordomas make up about 20% of all primary spinal tumors.
• They represent only 3% of all bone tumors.
• The most common place for chordomas is in the sacrum/coccygeal region (the lower part of the spine), accounting for 50% of cases.
• About 35% are found in the spheno-occipital region (the base of the skull).
• The rest, around 10% to 15%, are located in the mobile part of the spine.

Signs and Symptoms of Chordoma

Chordoma is a rare type of cancer that can occur at different locations in the body. The symptoms vary depending on where the cancer is. For example:

• Chordomas in the base of the skull typically cause headaches and problems with the cranial nerves, which are the nerves that come out from the brain. The most commonly affected is cranial nerve VI, also known as the abducens nerve. Sometimes other cranial nerves get involved too. Occasionally, these chordomas can cause a runny nose due to leakage of the fluid that surrounds the brain and spinal cord.
• Chordomas in the neck region can cause non-specific neck, shoulder, or arm pain. Sometimes, they can cause difficulty swallowing due to the growing mass. Additionally, these chordomas can move upward and affect the lower cranial nerves as well as press upon the spinal cord or nerves that branch out from it, causing symptoms of myelopathy (spinal cord dysfunction) or radiculopathy (nerve root dysfunction).
• Chordomas in the chest and lower back region also cause non-specific localized pain. They can sometimes weaken the bone to such an extent that it breaks even due to minor injuries (pathologic fracture). These chordomas too can compress the nerve roots or spinal cord, resulting in radiculopathy or myelopathy.
• Sacral chordomas, ones located at the base of the spine, not only cause localized pain and radiculopathy but can also affect the functioning of the bladder, bowel, or the autonomic nervous system, which controls body functions that we don’t consciously regulate, like heartbeat and digestion. This happens when the cancer involves the lumbosacral plexus, a network of nerves in the lower back.

Testing for Chordoma

If you’re being checked for chordomas, which are rare types of bone cancer, your doctor will rely on imaging and a biopsy. An x-ray can reveal a certain pattern of bone damage indicative of this disease. However, a computed tomography (CT) scan is even better at highlighting this. Sometimes, the edges of the chordoma will have a hardened, or ‘sclerotic’, look. Chordomas look less dense than bones on a CT scan and may have irregular chunks of hardened tissue or ‘calcification’. When a contrast agent is used, chordomas will look more visible or ‘enhanced’ on the CT images.

Magnetic resonance imaging (MRI) provides the most detailed view of the chordoma’s size and shape. Chordomas tend to have a lower intensity signal on T1-weighted imaging, a type of MRI scan, and can sometimes show brighter spots indicating bleeding within the tumor. When a contrast agent is used with T1-weighted imaging, the tumor will show variable enhancement, often having a honeycomb-like appearance. On T2-weighted imaging, another type of MRI scan, chordomas usually have a high-intensity signal. A specific kind of MRI scan, known as gradient-echo imaging, can confirm if there is bleeding within the tumor.

Bone scans might be conducted during the evaluation process. Chordomas tend to have normal to lower-than-normal uptake, indicating how the bone is reacting to the disease.

A diagnosis is confirmed by a needle or open biopsy. This involves taking a small piece of tissue from the tumor to be examined under a microscope. However, during biopsy planning and performance, care should be taken to avoid spreading of the cancer cells along the path of the biopsy needle. It is recommended that the biopsy tract (the path made by the needle) should also be removed during the future tumor removal surgery to reduce the risk of local recurrence or the cancer returning.

Treatment Options for Chordoma

The most effective treatment for prolonging survival is the complete surgical removal of the tumor, ensuring that no tumor cells remain at the surgical edges. However, this can be challenging depending on the location of the chordoma (a type of spinal tumor), or the need for reconstruction after its removal. Removing the tumor in pieces or partially may also prove beneficial, especially if the entire tumor can be removed without spreading the cancer cells. Sometimes, if it’s not possible to completely remove the tumor, reducing its size can help relieve the symptoms that result from the tumor pressing on nearby structures, and make future radiation therapy more effective.

Doctors typically recommend radiation therapy after any type of surgery for chordomas, due to their high chances of returning. Because chordomas tend to resist radiation, high-dose radiation therapy is needed. Since these tumors are usually located near the nerves, particular types of radiation therapy that focus the radiation more precisely are used, including proton beam radiation or radiosurgery. Regular radiation therapy that uses light waves (photon radiation) is currently not considered helpful for patients with chordomas.

Chordomas grow slowly, which makes them resistant to most standard chemotherapy drugs. If a patient’s chordoma is being treated with chemotherapy, it’s usually done within a clinical trial.

Because chordomas often return in the same area, doctors generally advise lifelong monitoring using a type of scan called an MRI, both with and without a contrast dye called gadolinium. If new tumors appear elsewhere in the body, it could mean that the chordoma has spread; this can happen in up to 20% of people with chordomas.

What else can Chordoma be?

At the base of the skull (clival/spheno-occipital area), various different types of abnormalities may be found. These could include:

• A benign notochordal cell tumor (a generally harmless tumor originating from the cells of the notochord)
• Chondrosarcoma (a type of cancer that usually affects the bones)
• Ecchordosis physaliphora (a rare, usually harmless condition involving the notochord)
• Meningioma (a mostly benign tumor that forms in the meninges, the layers of tissues that surround the brain and spinal cord)
• Pituitary macroadenoma (a larger type of pituitary gland tumor)
• Plasmacytoma (a type of bone marrow cancer)

In the vertebral area (spine), various abnormalities can be seen as well. These may include:

• Chondrosarcoma (as mentioned above)
• Giant cell tumor (a type of bone tumor that usually affects the legs)
• Plasmacytoma (as mentioned above)
• Spinal metastases (cancer cells that have moved from their original location to the spine)
• Spinal lymphoma (a type of lymphoma, or cancer that starts in cells which are part of the body’s immune system, that affects the spine)