Chordoma Foundation


  • Ablative therapy - A treatment that delivers extreme heat or cold to a tumor using small needles or probes inserted directly into the tumor. Ablative therapies include cryoablation, high-intensity focused ultrasound, and radiofrequency ablation.
  • Advanced medical directive - A legal document that specifies what actions should or should not be taken for an individual’s health if they are no longer able to make decisions for themselves because of illness or incapacitation.
  • Angiography - An imaging test that is done before surgery to show the location of important blood vessels.
  • Benign - Tumors that do not invade and destroy nearby tissue or spread to other parts of the body.
  • Biopsy - A procedure that uses a needle to remove a small tissue sample from the tumor to be tested in order to make a diagnosis.
  • Brachytherapy - A type of radiation therapy in which a small amount of radioactive material is placed inside the body to kill cancer cells.
  • Brachyury - A gene that makes a protein, also called brachyury, that is present at high levels in nearly all chordoma tumors.
  • Brainstem - The brainstem is the lower part of the brain connected to the spinal cord. The brainstem relays all signals to and from the brain and the body and is responsible for maintaining consciousness, breathing, and heartbeat.
  • Carbon ion therapy - A type of particle therapy that uses beams of charged carbon ions to kill cancer cells. Carbon ion therapy can deliver high doses of radiation to a tumor while sparing surrounding normal tissue.
  • Carotid artery - A major artery that provides the brain, head, and neck with oxygenated blood.
  • Cervical spine - The seven vertebrae that make up the neck. These vertebrae are commonly referred to as C1-C7.
  • Chemotherapy - A type of systemic therapy that is designed to kill rapidly dividing cancer cells.
  • Chondroid - One of the four histological types of chordoma, this term was more commonly used in the past when it was difficult to tell the difference between conventional chordoma and chondrosarcoma. Chondroid chordomas behave similarly to and are treated the same as conventional chordomas. 
  • Chondrosarcoma - Malignant tumors of cartilage cells that occur in or near the bones.
  • Chordoma Global Consensus Group - A multidisciplinary, international group of over 60 doctors who have extensive experience caring for chordoma patients. The group is responsible for developing and publishing consensus guidelines, based on all available medical and scientific evidence, for the treatment of primary and recurrent chordoma.
  • Clinical trial - Research studies involving human subjects that are done to test whether a treatment is safe, and how well it will work to treat a specific disease.
  • Clivus - The surface of a portion of bone at the base of the skull. It is surrounded by the brainstem and both carotid arteries. Chordomas that form in this area are called clival chordomas.
  • Coccyx - The final segment of the human vertebral column, commonly called the tailbone. It consists of 3 to 5 fused vertebrae below the sacrum.
  • Complete resection - All visible tumor has been removed, but not necessarily in one piece.
  • Computed tomography - A type of imaging scan that is used to help diagnose chordoma and can also be used to help guide the needle during a biopsy. They are also referred to as CT scans or “CAT” scans.
  • Conformal - Types of radiation that can focus the beam of radiation very accurately on the tumor while minimizing the amount of radiation that reaches the surrounding healthy tissue.
  • Contrast - A dye or other substance that is injected into a vein to help areas of the body show up more clearly on scans like MRIs and CTs.
  • Conventional chordoma - The most common histological subtype of chordoma, also called classic chordoma. It is composed of a unique cell type that looks like notochord cells and can show areas of chondroid dedifferentiation.
  • Core-needle biopsy - A type of biopsy performed with a wide needle. Also called a core biopsy.
  • Cryoablation - A type of ablative therapy that uses a needle to deliver extreme cold to a tumor in order to kill cancer cells.
  • Curative - Treatments that are given for the purpose of curing a disease or providing long-term survival.
  • Debulking - Surgical removal of part of a tumor.
  • Dedifferentiated - A histological subtype of chordoma that is more aggressive and usually grows faster than conventional chordomas. Dedifferentiated chordomas occur in only 5 percent of patients, can have loss of the INI1 gene, and are more common in pediatric patients.
  • Differential diagnosis - The process of distinguishing a particular disease from others that share similar signs or symptoms.
  • Diffusion MRI - A type of MRI which can help doctors tell the difference between chordoma and chondrosarcoma, in order to make a correct diagnosis.
  • Drug therapy - The use of treatments like targeted therapies to kill cancer cells.
  • Dura - A water balloon-like sheath that covers the brain and spinal cord and encloses cerebral-spinal fluid. Intradural means inside the dura and extradural is outside the dura.
  • En-bloc - During surgery, removal of the entire tumor in one piece without cutting it into smaller pieces.
  • Endoscopic - Use of an instrument to look inside the body. Most skull base chordoma surgeries are done endoscopically through the nose.
  • External beam radiation - Radiation that is delivered from outside the body.
  • Extra-axial - Bones outside the axial skeleton, which includes the skull bones, sternum, rib cage, middle ear bones, and the vertebrae. Extra-axial chordomas, though very uncommon, have been reported in multiple locations throughout the body.
  • Extraosseus - Occurring outside the bone.
  • Family-oriented support - Any type of psychosocial, emotional, or other support that includes the family as well as the patient.
  • Fraction - The dose of radiation delivered during one session of radiation therapy.
  • Gene - A segment of genetic material that has a particular function. Humans have approximately 25,000 different genes. Every cell in the body has the same set of genes, however, different genes are turned on in different tissues, and at different times.
  • Gross total resection - All visible tumor has been removed, usually in more than one piece.
  • GyE - The abbreviation for gray equivalents, which refers to the unit of measurement for an absorbed dose of radiation.
  • High-intensity focused ultrasound - A type of ablative therapy that destroys cancer cells with high-frequency sound waves delivered from outside of the body.
  • Histological subtype - One of the four types of chordoma. Each of the four histological subtypes of chordoma appears different under the microscope, allowing pathologists to distinguish between them. They may also have different rates of growth and likelihood of metastasizing.
  • Histology - The study of tissues and cells under a microscope.
  • Hospice - A specific type of supportive care that is provided to patients who are near the end of life and have stopped treatments meant to cure or control their disease. The main goal is to help patients feel as comfortable as possible, and to support both patients and family members through the end of life process. If a treatment option becomes available, patients can be taken out of hospice care and receive that treatment.
  • Hypofractionated - A radiation treatment technique that gives larger doses of radiation over a smaller number of sessions. The total amount of radiation given is less than when standard fractionation is used, but the effect is the same.
  • Image guidance - The use of frequent imaging, such as MRI or CT, during radiation treatments to help direct the radiation to the right place.
  • Immunotherapy - Systemic therapies that are designed to teach the immune system how to find and destroy cancer cells.
  • Incidence - The number of people diagnosed with chordoma in a particular time frame. For example, in the United States the incidence of chordoma is approximately 300 new diagnoses per year. See prevalence for information about the number of people living with chordoma at any given time.
  • Incomplete resection - Visible tumor tissue has been left behind after surgery.
  • Informed consent - The process during which patients are given complete information about a treatment or clinical trial, including possible risks and benefits, so they can decide whether to have the treatment or participate in the trial. For clinical trials, this includes patient rights, including the ability to withdraw consent and leave the trial at any time.
  • Inherited - Genetic traits that are passed down from parents to offspring.
  • INI1 - A protein that regulates the growth of certain tumor cells. Poorly differentiated chordoma tumors are characterized by loss of INI1. Also called SMARCB1.
  • Intensity-modulated radiation therapy - A type of radiation that uses computer assistance to deliver beams of radiation to a specific location in the body. Also called IMRT.
  • Intralesional resection - Visible tumor tissue has been left behind or tumor cells have spilled into the surrounding area because the tumor was cut during surgery.
  • Intraosseous - Occurring inside the bone. Most chordomas begin inside bones in the skull and spine and extend outwards as they grow.
  • Intravenous - Any fluids given inside a vein. These could be treatment, medications, blood, or contrast dye for MRI and CT scans.
  • Isolated recurrence - A single recurrent tumor at or near the site of the original tumor.
  • Local recurrence - Tumor that has grown back in the same location after treatment.
  • Lumbar spine - The five vertebrae of the lower back, commonly referred to as L1-L5.
  • Magnetic resonance imaging - A type of imaging scan that is used initially to help diagnose chordoma, as well as during follow up to check for recurrence or metastasis.
  • Malignant - Tumors that can invade and destroy nearby tissue and spread to other parts of the body, making them life-threatening.
  • Marginal resection - Less than 1 millimeter of healthy tissue removed along with the tumor but no visible tumor tissue left behind.
  • Margins - The healthy tissue surrounding the tumor that is taken out along with the tumor to make sure that no cancer cells are left behind. Negative or wide margins mean no tumor cells can be detected in the healthy tissue, which lowers the chance of recurrence. 
  • Metastatic - When tumors have spread to other parts of the body from the original tumor site.
  • Mobile spine - The parts of the spine not including the sacrum. The cervical spine (neck), thoracic spine (upper back), and lumbar spine (lower back) are the parts of the mobile spine.
  • Multidisciplinary - Treatment that involves a team of physicians from various disciplines. In the case of chordoma, these disciplines include sarcoma or bone pathology, radiology, spine surgery or skull base surgery, otolaryngology, radiation oncology, medical oncology, and palliative care.
  • Multifocal recurrence - Multiple tumors at or near the site of the original tumor that have regrown after treatment.
  • Mutation - A change in the genetic information (DNA) in a cell. Mutations occur every day all over the body and are usually harmless. In some cases, the mutations allow the cells to hide from the immune system and grow out of control, forming tumors.
  • Neuropathic pain - Chronic pain caused by nerve damage.
  • Neurophysiological monitoring - The use of devices during surgery to monitor the functioning of neural structures such as the spinal cord, nerves, and brain. This is done to guide the surgeon during the operation, and to reduce the risk of damage to the patient’s nervous system.
  • Notochord - The tissue in a fetus that acts as the building blocks for the spine. The notochord disappears when the fetus is about 8 weeks old, but some notochord cells are left behind in the bones of the skull and spine.
  • Off-label - The practice of prescribing drug treatments that are not approved by government agencies to treat a particular disease. Doctors are allowed to prescribe drugs off-label if they believe it is in the best interest of the patient.
  • Optic nerve - The nerve responsible for eyesight by sending signals from the eye to the brain.
  • Outcome - The health condition of a person after being diagnosed and treated for a particular disease. Outcome is usually measured at different time points. For example: one-, five-, or ten-year outcome.
  • Palliative care - Care given to improve the quality of life of patients who have a serious or life-threatening disease.
  • Particle therapy - A type of external beam radiation that uses beams of protons, neutrons, or positive ions for the treatment of cancer.
  • Photon therapy - A type of external beam radiation that uses x-rays to kill cancer cells.
  • Poorly differentiated - A histological subtype of chordoma that is more aggressive and usually grows faster than the conventional type. It is more common in children and young adults, and is often characterized by loss of the INI1 protein.
  • Prevalence - The number of people living with chordoma in a defined population. For example, at any given time there are fewer than one in 100,000 people living with chordoma around the world. See incidence for information about the number of people diagnosed with chordoma every year.
  • Prognosis - A term used for a doctor’s prediction of how a patient’s disease will progress.
  • Proliferation - The growth and division of tumor cells. Most normal cells balance proliferation with cell death to keep a constant number of cells. Cancer cells divide rapidly and avoid death, causing an accumulation of cells and eventually the formation of a tumor. Proliferation rate is how quickly the cells are growing and dividing.
  • Proton therapy - A type of particle therapy that uses beams of protons to kill cancer cells.
  • Radiofrequency ablation - A procedure that uses a needle to deliver energy to the tumor, causing it to heat up, and killing the cancer cells within it.
  • Recurrence - Tumor that has grown back after initial treatment. Recurrences can be isolated or multifocal, local or regional.
  • Referral center - A hospital, treatment center, or network of treatment centers where doctors have expertise in particular diseases.
  • Regional recurrence - Tumor that has grown back in the area adjacent to where the primary tumor was located.
  • Sacrum - The five vertebrae at the base of the spine near the pelvis, and between the two hip bones. These bones are commonly referred to as S1-S5.
  • Sarcoma - Cancer of bone and connective tissue such as cartilage, fat, muscle, and blood vessels. Chordoma is a type of sarcoma.
  • Seeding - Tumor cells deposited along the path of a biopsy needle or left in areas around the tumor during surgery, which will eventually grow into tumors. Seeding is a major concern for chordoma tumors and care should be taken to prevent it.
  • Skull base - The bones at the bottom part of the skull that separate the brain from other structures. The clivus is one of the bones of the skull base.
  • Somatic pain - Pain that results from the activation of sensory receptors even in the absence of injury or damage. It is one of the most common types of pain experienced by cancer patients.
  • Sporadic - Cancer occurring in individuals without a family history of the same type of cancer. Sporadic cancers are those not caused by an inherited high-risk genetic mutation.
  • Stage of disease -  For chordoma, stage of disease refers to primary/new diagnosis, recurrent disease, advanced disease, and metastatic disease. This is different than other types of cancers that are usually staged by the numbers 0-4.
  • Stereotactic body radiation therapy - A type of external beam radiation that uses special equipment to position a patient and precisely deliver radiation to tumors in all parts of the body except the brain, over a small number of treatments.
  • Stereotactic radiosurgery - A type of external beam radiation that uses special equipment to position a patient and precisely deliver radiation to tumors in or near the brain, over a small number of treatments.
  • Systemic therapy - The use of drugs that spread through the body to kill cancer cells. Also called chemotherapy or drug therapy.
  • Thoracic spine - The twelve vertebrae of the upper and mid back, extending from the shoulders to the bottom of the rib cage. These bones are commonly referred to as T1-T12.
  • Treatment couch - A special type of table used during radiation treatments. The couch can be moved in many different directions in order to accurately position the patient for treatment. If anything is being used to stabilize part of the body for treatment, it is usually attached to the treatment couch.
  • Treatment sequelae - A chronic condition or injury resulting from treatment for a disease.
  • Trocar CT-guided biopsy - A type of biopsy that uses a needle encased in a tube to retrieve a tumor sample and a CT scanner to guide the placement of the biopsy needle. This type of biopsy can help reduce the chance of spreading tumor cells.
  • Trocar CT-guided biopsy - A type of biopsy that uses a CT scanner to guide the placement of the biopsy needle. This is the type of biopsy that is recommended for chordoma to reduce the chance of spreading tumor cells.
  • Tuberous Sclerosis Complex - A rare autosomal dominant genetic disease that causes non-cancerous tumors to grow in the brain and on other vital organs such as the kidneys, heart, liver, eyes, lungs, and skin. 
  • Tumor board - A group of different types of specialists within a medical center who meet regularly to review each patient’s situation and make treatment recommendations.
  • Vertebrae - The bones that make up the spinal column and surround the spinal cord.
  • Wide resection - Removal of the entire tumor with at least 1 millimeter of healthy tissue surrounding the tumor.

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