Glossary of Terms

This glossary defines terms used within this web site. All definitions are referenced from the Dictionary of Cancer Terms provided by the National Cancer Institute.

Acute myeloid leukemia (uh-KYOOT MY-eh-loyd loo-KEE-mee-uh)
An aggressive (fast-growing) disease in which too many myeloblasts (immature white blood cells that are not lymphoblasts) are found in the bone marrow and blood. Also called acute myeloblastic leukemia, acute myelogenous leukemia, acute nonlymphocytic leukemia, and AML.
Acute lymphoblastic leukemia (uh-KYOOT LIM-foh-BLAS-tik loo-KEE-mee-uh)
An aggressive (fast-growing) type of leukemia (blood cancer) in which too many lymphoblasts (immature white blood cells) are found in the blood and bone marrow. Also called acute lymphocytic leukemia and ALL.
Alkylating agent (AL-kuh-LAY-ting AY-jent)
A type of drug that is used in the treatment of cancer. It interferes with the cell’s DNA and inhibits cancer cell growth.
Allogeneic (A-loh-jeh-NAY-ik)
Taken from different individuals of the same species. Also called allogenic.
Autologous (aw-TAH-luh-gus)
Taken from an individual’s own tissues, cells, or DNA.
A chemical that is used widely by the chemical industry, and is also found in tobacco smoke, vehicle emissions, and gasoline fumes. Exposure to benzene may increase the risk of developing leukemia.
An immature blood cell.
Bioinformatics (BY-oh-in-for-MA-tix)
The science of using computers, databases, and math to organize and analyze large amounts of biological, medical, and health information. Information may come from many sources, including patient statistics, tissue specimens, genetics research, and clinical trials.
Biomarker (BY-oh-MAR-ker)
A biological molecule found in blood, other body fluids, or tissues that is a sign of a normal or abnormal process, or of a condition or disease. A biomarker may be used to see how well the body responds to a treatment for a disease or condition. Also called molecular marker and signature molecule.
Biopsy (BY-op-see)
The removal of cells or tissues for examination by a pathologist. The pathologist may study the tissue under a microscope or perform other tests on the cells or tissue. There are many different types of biopsy procedures. The most common types include: (1) incisional biopsy, in which only a sample of tissue is removed; (2) excisional biopsy, in which an entire lump or suspicious area is removed; and (3) needle biopsy, in which a sample of tissue or fluid is removed with a needle. When a wide needle is used, the procedure is called a core biopsy. When a thin needle is used, the procedure is called a fine-needle aspiration biopsy.
Bone marrow (bone MAYR-oh)
The soft, sponge-like tissue in the center of most bones. It produces white blood cells, red blood cells, and platelets.
Bone marrow aspiration (bone MAYR-oh AS-pih-RAY-shun)
A procedure in which a small sample of bone marrow is removed, usually from the hip bone, breastbone, or thigh bone. A small area of skin and the surface of the bone underneath are numbed with an anesthetic. Then, a special wide needle is pushed into the bone. A sample of liquid bone marrow is removed with a syringe attached to the needle. The bone marrow is sent to a laboratory to be looked at under a microscope. This procedure may be done at the same time as a bone marrow biopsy.
Bone marrow transplantation (bone MAYR-oh tranz-plan-TAY-shun)
A procedure to replace bone marrow that has been destroyed by treatment with high doses of anticancer drugs or radiation. Transplantation may be autologous (an individual’s own marrow saved before treatment), allogeneic (marrow donated by someone else), or syngeneic (marrow donated by an identical twin).
Cancer (KAN-ser)
A term for diseases in which abnormal cells divide without control and can invade nearby tissues. Cancer cells can also spread to other parts of the body through the blood and lymph systems. There are several main types of cancer. Carcinoma is a cancer that begins in the skin or in tissues that line or cover internal organs. Sarcoma is a cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. Leukemia is a cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the blood. Lymphoma and multiple myeloma are cancers that begin in the cells of the immune system. Central nervous system cancers are cancers that begin in the tissues of the brain and spinal cord. Also called malignancy.
Cell (sel)
The individual unit that makes up the tissues of the body. All living things are made up of one or more cells.
Chemotherapy (KEE-moh-THAYR-uh-pee)
Treatment with drugs that kill cancer cells.
Chromatin immunoprecipitation-sequencing (ChIP-Seq)
A research technique that identifies the physical interactions between DNA and transcription factors and the identity of these associated factors.
Chromosome (KROH-muh-some)
Part of a cell that contains genetic information. Except for sperm and eggs, all human cells contain 46 chromosomes.
Chronic myeloid leukemia (KRAH-nik MY-eh-loyd loo-KEE-mee-uh)
A slowly progressing disease in which too many white blood cells (not lymphocytes) are made in the bone marrow. Also called chronic granulocytic leukemia, chronic myelogenous leukemia, and CML.
Clinical trial (KLIH-nih-kul TRY-ul)
A type of research study that tests how well new medical approaches work in people. These studies test new methods of screening, prevention, diagnosis, or treatment of a disease. Also called clinical study.
Computational modeling
The use of advanced computer technology to simulate the behavior of a system.
Congenital neutropenia (kon-JEH-nih-tul noo-troh-PEE-nee-uh)
An inherited disorder in which there is a lower-than-normal number of neutrophils (a type of white blood cell that is important in fighting infections). Infants with the disorder get infections caused by bacteria, and are at an increased risk of acute myelogenous leukemia (AML) or myelodysplasia (a bone marrow disorder). Also called genetic infantile agranulocytosis, infantile genetic agranulocytosis, Kostmann disease, Kostmann neutropenia, and Kostmann syndrome.
Consolidation therapy (kun-SAH-lih-DAY-shun THAYR-uh-pee)
Treatment that is given after cancer has disappeared following the initial therapy. Consolidation therapy is used to kill any cancer cells that may be left in the body. It may include radiation therapy, a stem cell transplant, or treatment with drugs that kill cancer cells. Also called intensification therapy and postremission therapy.
Controlled study (kun-TROLD STUH-dee)
An experiment or clinical trial that includes a comparison (control) group.
Cytarabine (sy-TAYR-uh-been)
A drug used to treat certain types of leukemia and prevent the spread of leukemia to the meninges (three thin layers of tissue that cover and protect the brain and spinal cord). It is also being studied in the treatment of other types of cancer. Cytarabine blocks tumor growth by stopping DNA synthesis. It is a type of antimetabolite.
Cytogenetics (SY-toh-jeh-NEH-tix)
The study of chromosomes and chromosomal abnormalities.
Daunorubicin (DAW-noh-ROO-bih-sin)
The active ingredient in a drug used to treat acute leukemias and some other types of cancer. It blocks a certain enzyme needed for cell division and DNA repair, and it may kill cancer cells. It is a type of anthracycline antibiotic and a type of topoisomerase inhibitor. Also called daunomycin.
Dendritic cell
A special type of immune cell that is found in tissues, such as the skin, and boosts immune responses by showing antigens on its surface to other cells of the immune system. A dendritic cell is a type of phagocyte and a type of antigen-presenting cell (APC).
The molecules inside cells that carry genetic information and pass it from one generation to the next. Also called deoxyribonucleic acid.
DNA hypomethylating agent
A drug that inhibits DNA methylation, which is a chemical process that involves the addition of methyl groups to DNA.
Down syndrome (…SIN-drome)
A disorder caused by the presence of an extra chromosome 21 and characterized by mental retardation and distinguishing physical features.
Drug resistance (… rih-ZIH-stunts)
The failure of cancer cells, viruses, or bacteria to respond to a drug used to kill or weaken them. The cells, viruses, or bacteria may be resistant to the drug at the beginning of treatment, or may become resistant after being exposed to the drug.
Etiology (EE-tee-AH-loh-jee)
The cause or origin of disease.
Etoposide (ee-toh-POH-side)
A drug used to treat testicular and small cell lung cancers. It is also being studied in the treatment of several other types of cancer. Etoposide blocks certain enzymes needed for cell division and DNA repair, and it may kill cancer cells. It is a type of podophyllotoxin derivative and a type of topoisomerase inhibitor. Also called Toposar and Vepesid.
Fanconi anemia (fan-KOH-nee uh-NEE-mee-uh)
A rare inherited disorder in which the bone marrow does not make blood cells. It is usually diagnosed in children between 2 and 15 years old. Symptoms include frequent infections, easy bleeding, and extreme tiredness. People with Fanconi anemia may have a small skeleton and brown spots on the skin. They also have an increased risk of developing certain types of cancer.
Gene (JEEN)
The functional and physical unit of heredity passed from parent to offspring. Genes are pieces of DNA, and most genes contain the information for making a specific protein.
Gene expression (JEEN ek-SPREH-shun)
The process by which a gene gets turned on in a cell to make RNA and proteins. Gene expression may be measured by looking at the RNA, or the protein made from the RNA, or what the protein does in a cell.
Genetic (jeh-NEH-tik)
Inherited; having to do with information that is passed from parents to offspring through genes in sperm and egg cells.
Genetics (jeh-NEH-tix)
The study of genes and heredity. Heredity is the passing of genetic information and traits (such as eye color and an increased chance of getting a certain disease) from parents to offspring.
Genetic marker (jeh-NEH-tik MAR-ker)
Alteration in DNA that may indicate an increased risk of developing a specific disease or disorder.
Genetic profile (jeh-NEH-tik PROH-file)
Information about specific genes, including variations and gene expression, in an individual or in a certain type of tissue. A genetic profile may be used to help diagnose a disease or learn how the disease may progress or respond to treatment with drugs or radiation.
Genetic susceptibility (jeh-NEH-tik suh-SEP-tih-BIH-lih-tee)
An inherited increase in the risk of developing a disease. Also called genetic predisposition.
Genetic test (jeh-NEH-tik TES-t)
The analysis of DNA to look for a genetic alteration that may indicate an increased risk for developing a specific disease or disorder.
Genome (JEE-nome)
The complete genetic material of an organism.
Genomics (jeh-NOH-mix)
The study of the complete genetic material, including genes and their functions, of an organism.
Genomic profile (jeh-NOH-mik PROH-file)
Information about all the genes in an organism, including variations, gene expression, and the way those genes interact with each other and with the environment. A genomic profile may be used to discover why some people get certain diseases while other people do not, or why people respond differently to the same drug.
Genomic profiling
The process by which information about all of an individual’s genes is determined.
Genome-wide association study (JEE-nome … uh-SOH-see-AY-shun STUH-dee)
A study that compares the complete DNA of people with a disease or condition to the DNA of people without the disease or condition. These studies find the genes involved in a disease, and may help prevent, diagnose, and treat the disease. Also called GWAS, WGA study, and whole genome association study.
Gleevec (GLEE-vek)
A drug used to treat different types of leukemia and other cancers of the blood, gastrointestinal stromal tumors, skin tumors called dermatofibrosarcoma protuberans, and a rare condition called systemic mastocytosis. It is also being studied in the treatment of other types of cancer. Gleevec blocks the protein made by the bcr/abl oncogene. It is a type of tyrosine kinase inhibitor. Also called imatinib mesylate and STI571.
Glucocorticoid (GLOO-koh-KOR-tih-koyd)
A compound that belongs to the family of compounds called corticosteroids (steroids). Glucocorticoids affect metabolism and have anti-inflammatory and immunosuppressive effects. They may be naturally produced (hormones) or synthetic (drugs).
Hematologist (HEE-muh-TAH-loh-jist)
A doctor who specializes in treating blood disorders.
Hematopoiesis (hee-MA-toh-poy-EE-sus)
The formation of new blood cells.
Immune system (ih-MYOON SIS-tem)
The complex group of organs and cells that defends the body against infections and other diseases.
Immunosuppressive (IH-myoo-noh-suh-PREH-siv)
Describes the ability to decrease the body’s immune system responses.
Induction therapy (in-DUK-shun THAYR-uh-pee)
Initial treatment used to reduce a cancer. Induction therapy is followed by other treatments, such as chemotherapy, radiation therapy, and hormone therapy to get rid of cancer that remains. Also called first-line therapy, primary therapy, and primary treatment.
The application of computer and statistical methods to manage information.
Investigational drug (in-VES-tih-GAY-shuh-nul drug)
A substance that has been tested in a laboratory and has gotten approval from the U.S. Food and Drug Administration (FDA) to be tested in people. An investigational drug may be approved by the FDA for use in one disease or condition but be considered investigational in other diseases or conditions. Also called experimental drug and investigational agent.
In vivo
In the body. The opposite of in vitro (outside the body or in the laboratory).
Leukemia (loo-KEE-mee-uh)
Cancer that starts in blood-forming tissue such as the bone marrow and causes large numbers of blood cells to be produced and enter the bloodstream.
Lymphocyte (LIM-foh-site)
A type of immune cell that is made in the bone marrow and is found in the blood and in lymph tissue. The two main types of lymphocytes are B lymphocytes and T lymphocytes. B lymphocytes make antibodies, and T lymphocytes help kill tumor cells and help control immune responses. A lymphocyte is a type of white blood cell.
Lymphoid (LIM-foyd)
Referring to lymphocytes, a type of white blood cell. Also refers to tissue in which lymphocytes develop.
Lymphoma (lim-FOH-muh)
Cancer that begins in cells of the immune system. There are two basic categories of lymphomas. One kind is Hodgkin lymphoma, which is marked by the presence of a type of cell called the Reed-Sternberg cell. The other category is non-Hodgkin lymphomas, which includes a large, diverse group of cancers of immune system cells. Non-Hodgkin lymphomas can be further divided into cancers that have an indolent (slow-growing) course and those that have an aggressive (fast-growing) course. These subtypes behave and respond to treatment differently. Both Hodgkin and non-Hodgkin lymphomas can occur in children and adults, and prognosis and treatment depend on the stage and the type of cancer.
Lymph node (limf node)
A rounded mass of lymphatic tissue that is surrounded by a capsule of connective tissue. Lymph nodes filter lymph (lymphatic fluid), and they store lymphocytes (white blood cells). They are located along lymphatic vessels. Also called lymph gland.
A type of white blood cell that surrounds and kills microorganisms, removes dead cells, and stimulates the action of other immune system cells.
Malignant (muh-LIG-nunt)
Cancerous. Malignant tumors can invade and destroy nearby tissue and spread to other parts of the body.
Mast cell
A type of white blood cell.
Metabolic (MEH-tuh-BAH-lik)
Having to do with metabolism (the total of all chemical changes that take place in a cell or an organism to produce energy and basic materials needed for important life processes).
Methylation (MEH-thul-AY-shun)
A chemical reaction in which a small molecule called a methyl group is added to other molecules. Methylation of proteins or nucleic acids may affect how they act in the body.
Molecule (MAH-leh-kyool)
The smallest particle of a substance that has all of the physical and chemical properties of that substance. Molecules are made up of one or more atoms. If they contain more than one atom, the atoms can be the same (an oxygen molecule has two oxygen atoms) or different (a water molecule has two hydrogen atoms and one oxygen atom). Biological molecules, such as proteins and DNA, can be made up of many thousands of atoms.
each other. Translocations may lead to medical problems such as leukemia, breast cancer, schizophrenia, muscular dystrophy, and Down syndrome.
Molecular pathway (muh-LEH-kyoo-ler …)
A series of actions among molecules in a cell that leads to a certain end point or cell function.
Molecularly targeted therapy (muh-LEH-kyuh-ler-lee TAR-geh-ted THAYR-uh-pee)
In cancer treatment, substances that kill cancer cells by targeting key molecules involved in cancer cell growth.
Multiple myeloma (MUL-tih-pul MY-eh-LOH-muh)
A type of cancer that begins in plasma cells (white blood cells that produce antibodies). Also called Kahler disease, myelomatosis, and plasma cell myeloma.
Myeloblast (MY-eh-loh-BLAS-t)
A type of immature cell that forms in the bone marrow
Myelodysplastic syndrome (MY-eh-loh-dis-PLAS-tik SIN-dromz)
A group of diseases in which the bone marrow does not make enough healthy blood cells. Also called preleukemia and smoldering leukemia.
Myeloid (MY-eh-loyd)
Having to do with or resembling the bone marrow. May also refer to certain types of hematopoietic (blood-forming) cells found in the bone marrow. Sometimes used as a synonym for myelogenous; for example, acute myeloid leukemia and acute myelogenous leukemia are the same disease.
Myeloproliferative disorder (MY-eh-loh-pruh-LIH-feh-RUH-tiv dis-OR-der)
A group of slow growing blood cancers, including chronic myelogenous leukemia, in which large numbers of abnormal red blood cells, white blood cells, or platelets grow and spread in the bone marrow and the peripheral blood.
Neutrophil (NOO-tro-fil)
A type of immune cell that is one of the first cell types to travel to the site of an infection. Neutrophils help fight infection by ingesting microorganisms and releasing enzymes that kill the microorganisms. A neutrophil is a type of white blood cell, a type of granulocyte, and a type of phagocyte.
Nucleotide (NOO-klee-oh-TIDE)
A building block for nucleic acids (the molecules inside cells that carry genetic information). Nucleotides are attached end-to-end to form the nucleic acids DNA and RNA.

Oncologist (on-KAH-loh-jist)
A doctor who specializes in treating cancer. Some oncologists specialize in a particular type of cancer treatment. For example, a radiation oncologist specializes in treating cancer with radiation.
Oncology (on-KAH-loh-jee)
The study of cancer.
Personalized medicine
A form of medicine that uses information about a person’s genes, proteins, and environment to prevent, diagnose, and treat disease.
Pharmacogenetics (FAR-muh-koh-jeh-NEH-tix)
The study of how a person’s genes affect the way he or she responds to drugs. Pharmacogenetics is being used to learn ahead of time what the best drug or the best dose of a drug will be for a person. Also called pharmacogenomics.
Pharmacogenomics (FAR-muh-koh-jeh-NOH-mix)
The study of how a person’s genes affect the way he or she responds to drugs. Pharmacogenomics is being used to learn ahead of time what the best drug or the best dose of a drug will be for a person. Also called pharmacogenetics.
A field of science that involves the use of computational methods to model phenotypes, which are the observable characteristics of an individual that result from environmental and genetic factors.
Platelet (PLATE-let)
A tiny piece of a cell found in the blood that breaks off from a large cell found in the bone marrow. Platelets help wounds heal and prevent bleeding by forming blood clots. Also called thrombocyte.
Prevention (pree-VEN-shun)
In medicine, action taken to decrease the chance of getting a disease or condition. For example, cancer prevention includes avoiding risk factors (such as smoking, obesity, lack of exercise, and radiation exposure) and increasing protective factors (such as getting regular physical activity, staying at a healthy weight, and having a healthy diet).
Protein (PRO-teen)
A molecule made up of amino acids that are needed for the body to function properly. Proteins are the basis of body structures such as skin and hair and of substances such as enzymes, cytokines, and antibodies.
Radiation (RAY-dee-AY-shun)
Energy released in the form of particle or electromagnetic waves. Common sources of radiation include radon gas, cosmic rays from outer space, medical x-rays, and energy given off by a radioisotope (unstable form of a chemical element that releases radiation as it breaks down and becomes more stable).
Radiotherapy (RAY-dee-oh-THAYR-uh-pee)
The use of high-energy radiation from x-rays, gamma rays, neutrons, protons, and other sources to kill cancer cells and shrink tumors. Radiation may come from a machine outside the body (external-beam radiation therapy), or it may come from radioactive material placed in the body near cancer cells (internal radiation therapy). Systemic radiotherapy uses a radioactive substance, such as a radiolabeled monoclonal antibody, that travels in the blood to tissues throughout the body. Also called irradiation and radiation therapy.
Red blood cell
A cell that carries oxygen to all parts of the body. Also called erythrocyte and RBC.
A decrease in the size of a tumor or in the extent of cancer in the body.
A decrease in or disappearance of signs and symptoms of cancer. In partial remission, some, but not all, signs and symptoms of cancer have disappeared. In complete remission, all signs and symptoms of cancer have disappeared, although cancer still may be in the body.
One of two types of nucleic acid made by cells. RNA contains information that has been copied from DNA (the other type of nucleic acid). Cells make several different forms of RNA, and each form has a specific job in the cell. Many forms of RNA have functions related to making proteins. RNA is also the genetic material of some viruses instead of DNA. RNA can be made in the laboratory and used in research studies. Also called ribonucleic acid.
Screening (SKREEN-ing)
Checking for disease when there are no symptoms. Since screening may find diseases at an early stage, there may be a better chance of curing the disease. Examples of cancer screening tests are the mammogram (breast), colonoscopy (colon), Pap smear (cervix), and PSA blood level and digital rectal exam (prostate). Screening can also include checking for a person’s risk of developing an inherited disease by doing a genetic test.
Sickle cell disease (SIH-kul sel dih-ZEEZ)
An inherited disease in which the red blood cells have an abnormal crescent shape, block small blood vessels, and do not last as long as normal red blood cells. Sickle cell disease is caused by a mutation (change) in one of the genes for hemoglobin (the substance inside red blood cells that binds to oxygen and carries it from the lungs to the tissues). It is most common in people of West and Central African descent. Also called sickle cell anemia.
Side effect
A problem that occurs when treatment affects healthy tissues or organs. Some common side effects of cancer treatment are fatigue, pain, nausea, vomiting, decreased blood cell counts, hair loss, and mouth sores.
Single nucleotide polymorphism (… NOO-klee-oh-TIDE PAH-lee-MOR-fih-zum)
The most common type of change in DNA (molecules inside cells that carry genetic information). Single nucleotide polymorphisms occur when a single nucleotide (building block of DNA) is replaced with another. These changes may cause disease, and may affect how a person reacts to bacteria, viruses, drugs, and other substances. Also called SNP.
Stem cell
A cell from which other types of cells develop. For example, blood cells develop from blood-forming stem cells.
Stem cell transplantation (stem sel tranz-plan-TAY-shun)
A method of replacing immature blood-forming cells that were destroyed by cancer treatment. The stem cells are given to the person after treatment to help the bone marrow recover and continue producing healthy blood cells.
Systems biology
A term describing the study of interactions between the components of complex biological systems, and how these interactions influence both the behavior and the functions of these systems.
Targeted therapy (TAR-geh-ted THAYR-uh-pee)
A type of treatment that uses drugs or other substances, such as monoclonal antibodies, to identify and attack specific cancer cells. Targeted therapy may have fewer side effects than other types of cancer treatments.
Transcription (tran-SKRIP-shun)
In biology, the process by which a cell makes an RNA copy of a sequence of DNA that is a gene.
Translocation (TRANZ-loh-KAY-shun)
A genetic change in which a piece of one chromosome breaks off and attaches to another chromosome. Sometimes pieces from two different chromosomes will trade places with each other. Translocations may lead to medical problems such as leukemia, breast cancer, schizophrenia, muscular dystrophy, and Down syndrome.
Translational research (trans-LAY-shuh-nul reh-SERCH)
A term used to describe the process by which the results of research done in the laboratory are used to develop new ways to diagnose and treat disease.
White blood cell
A type of immune cell. Most white blood cells are made in the bone marrow and are found in the blood and lymph tissue. White blood cells help the body fight infections and other diseases. Granulocytes, monocytes, and lymphocytes are white blood cells. Also called leukocyte and WBC.