Understanding chordoma
Chordoma is not always easy to diagnose and it can be confused with other types of tumors. Getting the correct diagnosis from the start is critical to being able to find and choose the best treatment.
If you have had an MRI and been given a probable or differential diagnosis of chordoma, it is very important to find doctors who have experience diagnosing and treating chordoma patients to confirm the diagnosis. If you have had a biopsy and chordoma is confirmed, or if you have received a chordoma diagnosis following surgery, it is important for your case to be evaluated by a multidisciplinary team of chordoma experts who can talk with you about what next steps you should take.
Once you have been given a diagnosis, it can be helpful to get a second opinion to confirm the diagnosis before making treatment decisions. As with any rare cancer, second and even third opinions are important and reasonable steps to take.
It is important to go to a hospital, treatment center, or network of treatment centers where doctors have experience diagnosing and treating chordoma as soon as chordoma is suspected. You should avoid having a biopsy or surgery to confirm the diagnosis of chordoma outside of a referral center because, if not done properly, these procedures can cause the chordoma to spread.
Chordoma tumors are typically detected through imaging tests, which show organs and other structures inside the body, including tumors. The way the tumor looks on imaging tests can tell a radiologist whether it might be chordoma.
When a chordoma is suspected, you will need magnetic resonance imaging, also called MRI, to help doctors make a diagnosis and plan for treatment. An MRI is the best way to see a chordoma and how it is affecting the tissue around it, such as muscles, nerves, and blood vessels. No matter where the tumor is located, an MRI of the entire spine should be performed to see if the tumor may have spread to or developed in other areas of the spine. Chordoma is best seen on an MRI with a setting called T2 weighted imaging.
Another imaging test called computed tomography, also called CT or CAT scan, is recommended in addition to MRI if it is not certain whether the tumor is chordoma. CT scans of the chest, abdomen, and pelvis are recommended to make sure there is no spread of tumor. Imaging tests should be interpreted by a radiologist who has experience diagnosing bone tumors.
In some cases doctors may order a positron emission tomography, or PET, scan. These are usually whole-body scans that look for widespread tumor activity. PET scans provide information about your body’s metabolic function; for cancer specifically, PET scans pick up on tumors that are rapidly using glucose (sugar). Cancer cells metabolize much more glucose than regular cells, so tumors “light up” on the scan. Because chordoma cells typically grow slowly, however, they are not always picked up as well by PET scans, so they are not widely used in diagnosing chordoma.
Imaging tests can show the possibility of a chordoma, but a definitive diagnosis can only be made by a pathologist who examines a sample of tumor tissue under a microscope. For this reason, your medical team may consider taking a small sample of tissue from the tumor, called a biopsy, prior to surgery if the tumor can be reached safely (see important information below regarding biopsies).
Tissue samples should be evaluated by a pathologist who has experience diagnosing bone tumors. Your pathologist may test your tumor tissue for the presence of a protein called brachyury. Nearly all chordomas have high levels of brachyury, which makes it helpful for diagnosis.
For sacral and mobile spine tumors, a trocar CT-guided biopsy is recommended and should be done from the back. Trocar CT-guided biopsy uses a CT scan to precisely direct the biopsy needle to the correct location. The biopsy needle is enclosed in a tube to keep tumor cells from spreading along the path of the needle – this is often called seeding. Talk with your doctors to learn if they plan to use this method if a biopsy is recommended.
Skull base tumors can be difficult to reach safely for a biopsy, so your surgeon may opt for a biopsy during surgery. This means that a pathologist will be prepared to examine a sample of tumor tissue removed at the start of surgery and give an immediate diagnosis, and the surgical team will proceed with surgery based on that information.
If you have a biopsy before surgery, it is recommended that your surgeon take out the tissue around the area of the biopsy during surgery in order to remove any chordoma cells that might have spread when the biopsy disturbed the tumor.
The WHO Classification of Soft Tissue and Bone Tumours (5th edition, April 2020) defines the following three types of chordoma. These types are based on the histological appearance and characteristics of the tumor cells.
The Chordoma Foundation Medical Advisory Board suggests that chordoma patients under 35 years of age, or whose tumors are growing unusually fast, have their tumors tested for loss of INI1, either through immunohistochemistry (IHC) or genomic testing.
If tissue is not available for testing, the possibility of a biopsy to obtain tissue for this testing should be discussed with a doctor who has experience treating chordoma, carefully weighing the potential risks of biopsy. Interpretation of the testing should be done by a pathologist who has experience diagnosing chordoma.
Most common form of chordoma
Typically slow-growing
Composed of a unique type of cell with a “bubbly” appearance
Expresses the brachyury protein, which is a hallmark of chordoma and distinguishes conventional chordoma from other tumors like chondrosarcoma
Chondroid chordoma, previously a separate type, is now considered to be a kind of conventional chordoma
Very rare subtype that occurs in 5 percent or less of patients
Typically more aggressive, faster-growing, and more likely to metastasize than conventional chordoma
Can have different treatment options than conventional chordoma, including chemotherapy
Appears as a mix of conventional chordoma cells that express brachyury and cells that resemble high-grade sarcoma and do not express brachyury
Very rare subtype officially recognized for the first time in the most recent (2020) edition of the WHO classifications
Typically more aggressive, faster-growing, and more likely to metastasize than conventional chordoma
More common in younger patients as well as those with skull base and cervical tumors
Can have different treatment options than conventional chordoma, including chemotherapy
Expresses brachyury and a defining characteristic is deletion of a gene called SMARCB1, or INI1
Learn more about diagnosing chordoma in these videos from our Expert Answers Series.
The treatment recommendations you find here were developed by the Chordoma Global Consensus Group – a multidisciplinary, international group of over 60 doctors who specialize in caring for chordoma patients. The Chordoma Foundation and the European Society for Medical Oncology brought this group together to define the recommendations for treating and diagnosing chordoma based on all available medical and scientific evidence. The resulting consensus guidelines were published in the medical journal The Lancet Oncology in February 2015. You can also find these recommendations in our Expert Recommendations for the Diagnosis and Treatment of Chordoma booklet.
