Understanding chordoma in children and young adults and possible Treatment
Chordoma in children and young adults is rare, as the disease is most often diagnosed in people in their 50s and 60s. Patients under the age of 20 years old makeup only 5 percent of all chordoma cases. The skull base and cervical spine are the most common locations of chordoma in children and young adults, and the number of females diagnosed is slightly higher than the number of males.1 2 3 As discussed here, children and young adults are considered to be from birth to 35 years old. Chordoma Treatment is possible after it been diagnosed for the type it is.
There are four subtypes of chordoma, two of which — poorly differentiated and dedifferentiated — are more often found in children and young adults.
1. Conventional (or classic) chordoma is the most common form of chordoma. It is composed of a unique cell type that resembles notochordal cells and can have areas of chondroid appearance.
2. Poorly differentiated chordoma is a subtype that has recently been identified in the medical literature but is not yet recognized by the World Health Organization (WHO). It can be more aggressive and faster-growing than conventional chordoma and is characterized by a loss of a protein called INI1, also called SMARCB1. Poorly differentiated chordoma is more common in pediatric and young adult patients, and in skull base and cervical tumors.
3. Dedifferentiated chordoma is more aggressive and generally grows faster than the other types of chordoma, and is more likely to metastasize than conventional chordoma. It can also have a loss of the INI1 protein, but this is not common. This type of chordoma is rare, occurring in only about 5 percent of patients, and is more common in pediatric patients.
4. Chondroid chordoma is a term more commonly used in the past when it was difficult to distinguish conventional chordoma from chondrosarcoma. This is no longer a problem because brachyury is expressed in nearly all conventional chordomas, making them easier to distinguish from cartilaginous tumors like chondrosarcoma that do not express brachyury. There is no evidence that chordomas with a chondroid appearance behave differently than conventional types that do not have this appearance.
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Diagnosis of chordoma in children and young adults
If you or your child might have chordoma, the most important thing to do is to find a medical center with a team of experts who have experience caring for chordoma patients. For diagnosis, this team should include a radiologist and pathologist with chordoma experience.4 5
While imaging tests like an MRI or CT scan can show the possibility of a chordoma, a definitive diagnosis can only be made by a pathologist who examines a sample of the tumor tissue under a microscope. The pathologist will perform immunohistochemistry (IHC) testing for protein markers, such as brachyury, which helps them distinguish chordoma from other types of tumors. The process of removing tumor tissue for analysis is called a biopsy.
Considerations for pediatric and young adult patients
Pathologists also determine the subtype of chordoma with IHC testing. The subtype is determined by how the cells look under a microscope, and a specific kind of IHC test can also be done to help determine whether the tumor is poorly differentiated. This test looks to see whether a protein called INI1 is present or absent in the tumor cells. INI1 is typically absent in poorly differentiated chordoma and on rare occasion in conventional or dedifferentiated tumors as well.1 4 This is also called INI1 loss, or INI1 negative.
|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.|
Chordoma is less common in patients under the age of 35 than it is for older adults, and it affects very important and complex parts of the body. Appropriate treatment requires very specialized care provided by multiple types of doctors. This team approach involving multiple specialists is called multidisciplinary care. It is typically only found at larger hospitals, sometimes called referral centers, which see large numbers of patients.
Experts recommend your or your child’s chordoma treatment team include the following specialists:
- Radiation oncologist
- Medical oncologist
- Palliative and pain medicine specialist
Conventional and chondroid chordoma in children and young adults
In most cases of conventional chordoma in children and young adults, surgery is recommended as the first treatment. The goal of surgery is to remove as much of the tumor as possible without causing serious side effects. Radiation therapy is generally recommended after surgery to kill any remaining tumor cells,5 although in some cases radiation may be given both before and after surgery.
High doses of radiation are required to control chordoma. Specifically, a dose of at least 74 GyE (Gray Equivalents) is recommended. This dose should be given to any visible tumor as well as any areas where doctors believe there may be microscopic tumor remaining after surgery.5
What matters most about a radiation treatment plan is that it delivers this high dose to the areas that need it while also minimizing the dose that reaches important structures and healthy tissue nearby. For pediatric and young adult patients, it is also important to limit the total dose of radiation that goes into the rest of the body, to help reduce the risk of secondary cancers later in life.
Particle therapy is most often recommended for chordoma because it can deliver very high doses of radiation to the tumor while minimizing doses to nearby areas and the rest of the body.5 Proton beam therapy and carbon ion therapy are two types of particle therapy. Carbon ion is only available at a small number of centers in Europe and Asia. In some cases, radiation oncologists may use a combination of proton and photon therapy.
Poorly differentiated and dedifferentiated chordoma
Chordomas classified as poorly differentiated or dedifferentiated may have additional treatment options that are recommended along with, or in place of, surgery and radiation for initial diagnosis. There is some published evidence that conventional sarcoma chemotherapy regimens may be effective in treating poorly differentiated and dedifferentiated chordoma.6 7 8 9 These regimens include the drugs doxorubicin, ifosfamide, etoposide, vincristine, and cyclophosphamide.6 7 8 9
There are also clinical trials that may be options for patients with poorly differentiated and dedifferentiated tumors. Visit our Clinical Trials Catalogue to learn more. There are trials noted specifically for pediatric patients, while the trials listed for adults are enrolling patients over the age of 18 years old, and in some cases will accept patients as young as 16 years old. Participation in a clinical trial is recommended whenever possible for patients with poorly differentiated chordoma.1