Cancer Terms

To view a cancer term: search the National Cancer Institute Database or search by alphabetical order.

Alphabetical Dictionary Search



A.F.P. (Alpha feta protein): A tumor marker.

Acute: Describes a sudden onset of symptoms or disease.

Adenocarcinoma: A malignant tumor arising from glandular tissue.

Adenoma: A benign tumor made up of glandular tissue. For example, an adenoma of the pituitary gland may cause it to produce abnormal amounts of hormones.

Adjuvant chemotherapy: Chemotherapy given to kill any remaining cancer cells, usually after all detectable tumor is removed by surgery or radiotherapy.

Advance directive: Legal document that addresses the use of life support measures if required.

Alopecia: The loss of hair, which may include all body hair besides scalp hair.

Analgesic: Any drug that relieves pain. Aspirin and acetaminophen are mild analgesics.

Anemia: A condition in which a decreased number of red blood cells may cause symptoms including tiredness, shortness of breath, and weakness.

Anorexia: The loss of appetite.

Antibody: A substance produced by the body to defend the body against infection.

Antiemetics: Drugs that are used to decrease the sensation of nausea.

Antifungal: A drug used to treat fungal infections.

Antigen: A foreign substance in the body, such as protein, bacteria, viruses, or other materials, that stimulate the body to produce antibodies against them.

Antineoplastic agents: A drug that prevents, kills, or blocks the growth and spread of cancer cells.

Ascites: An accumulation of fluid within the abdomen that can occur in patients with non-cancerous conditions (e.g., liver cirrhosis) and with different types of cancer.

Aspiration: The process of removing fluid/tissue from a specific area.

Autologous: The infusion of a patient's own bone marrow previously taken and stored; an autologous transplant is tissue taken from a patient and returned to the same patient

Autoimmunity: A condition in which the body's immune system mistakenly fights and rejects body's own tissues.

Axilla: The armpit.

Axillary nodes: Lymph nodes - also called lymph glands - found in the armpit (axilla).

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Basal cell carcinoma:The most common type of skin cancer.

Benign: Describes a swelling or growth that is not cancerous and does not spread from one part of the body to another.

Biopsy: The surgical removal of tissue for microscopic examination for diagnosis.

Blood cells: Minute structures made in the bone marrow; consists of red blood cells, white blood cells, and platelets.

Blood count: A test that counts the number of different cells that are contained in the blood.

Bolus: A material which may be placed on the surface of the patient to increase the skin dose and/or even out irregular contours in the patient.

Bone marrow: The spongy material found inside the bones. Most blood cells are made in the bone marrow.

Bone marrow suppression: A decrease in the production number of blood cells.

Bone marrow biopsy and aspiration: The procedure by which a needle is inserted into a bone to withdraw a sample of the bone marrow.

Bone marrow transplant: The addition of bone marrow into a patient who has been treated with high-dose chemotherapy or radiation therapy. Patients may use their own marrow or that of another person.

Bone scan: A picture of the bones using a radioactive dye that shows any injury, disease, or healing. This is a valuable test to determine if cancer has spread to the bone, if anticancer therapy is successful, and if affected bony areas are healing.

Boost Treatment: A smaller area of radiation treatment concentrating on the tumor bed or tumor sight.

Brachytherapy: The administration of radiation therapy by inserting a radioactive source or applicator internally into the patient to deliver a high, concentrated dose to a specific sight. An example of this is a prostate seed implant.

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CA125: A blood protein that can be measured and is an important tumor market in ovarian cancer.

Cancer: A group of diseases in which malignant cells grow out of control and spread to other parts of the body.

Carcinogen: A substance that causes cancer. For example, nicotine in cigarettes is a carcinogen that causes lung cancer.

Carcinoma: A kind of cancer that starts in the skin or the lining of organs.

Squamous cell carcinoma: Cancer arising from the skin or the surfaces of other structures, such as the mouth, cervix, or lungs.

CAT scan: Computerized axial tomography, or CT scan, an x-ray test that produces cross-sectional images of the body that are more detailed than standard x-rays.

CEA (Carcinoembryonic antigen): A blood tumor marker.

Cell: The fundamental structural and functional unit of living organisms.

Cellulitis: The inflammation of an area of the skin (epithelial layer).

Central venous catheter: A special intravenous tubing that is surgically inserted into a large vein near the heart and exits from the chest or abdomen. The catheter allows medications, fluids, or blood products to be given and blood samples to be taken.

Chemotherapy: The treatment of cancer with drugs.

Chronic: Persisting over a long period of time.

Clinical trials: Also called "clinical studies." Research studies with people. Each trial tries to answer specific scientific questions and to find better ways to prevent, detect, or treat diseases or to improve care.

Combination chemotherapy: The use of more than one (generally between 2 and 4) different anticancer drugs to treat cancer.

Conformal radiation therapy (3D-CRT): Radiation treatment that uses sophisticated computer software to conform or shape the distribution of radiation beams to the 3-dimensional shape of an organ, sparing damage to normal tissue in the vicinity of treatment.

Consent form: A document signed by a patient which gives the individual’s permission for treatment; also, a document that provide key facts about a clinical trial.

CT/Simulation: The use of a CAT scan to obtain images for the guidance of precise radiation treatment portals. This is done on the CT table simulating the position the patient will be in for their treatments.

Curative treatment: A treatment intended to eradicate disease.

Custom Blocks: Customized shields placed in the treatment machine to shape the field according to the pattern the Radiation Oncologist designed. A custom compensator is a tool placed in the radiation beam to modify the dose distribution of the beam; it is designed for the individual patient when appropriate.

Cytotoxic Drug: A drug that skills specific cells in the body.

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Diagnose: To determine the cause of an illness or medical condition.

Diagnostic radiologist: A medical specialist trained to read x-rays.

Dosimetrist/Dosimetry: The use of a treatment planning computer system and the computerized tomography scans (CT) by specially trained individuals to develop a treatment plan that delivers the prescribed dose of radiation to the tumor volume and keeps the dose to the surrounding normal tissue at an acceptable level.

Drug resistance: The result of cells' ability to resist the effects of a specific drug.

Durable power of attorney: A legal document that gives a person or persons the authority to make decisions for another person.

Dysphagia: Difficulty swallowing either solids or liquids.

Dysplasia: An increase in both the number of cells in a tissue and in the size of those cells, a precancerous change.

Dyspnea: Difficult or painful breathing; shortness of breath.

Dysuria: Difficult or painful urination.

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Edema: The accumulation of fluid in part of the body.

Electrocardiogram (EKG or ECG): A test that makes recordings of the electrical activity of the heart.

Electron treatments: A type of radiation treatment that offers the ability to treat superficially located lesions with almost no dose to the deep underlying tissues.

End-of-life care: Palliative and supportive care given to persons with a terminal illness.

Enteral Feeding: A method of providing nutritional support to malnourished patients through tubes, e.g., a nasogastric tube or gastronomy tube.

Erythema: Redness of the skin.

Erythrocyte: The red blood cell that carries oxygen to the body cells and carbon dioxide away from body cells.

Estrogen: A female sex hormone secreted primarily by the ovaries that is responsible for secondary sex characteristics, such as the growth of breasts.

Estrogen Receptor Assay: A test done during the biopsy of cancerous tissue to determine if its growth depends on estrogen.

Excision: Surgical removal. An excisional biopsy is the surgical removal of an entire mass in order to determine what it is.

External beam radiation therapy: Radiation therapy that is given by directing a beam of radiation at the cancer from a source located outside of the body.

Extravasation: The leaking of intravenous fluids or medication into tissue surrounding the infusion site. Extravasation may cause tissue damage.

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Fatigue: A feeling of tiredness and lack of energy, related to cancer or cancer treatment or both.

Fine needle aspirate: A procedure in which a needle is inserted under local anesthesia to obtain a sample for the evaluation of suspicious tissue.

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Gene: The biologic unit of heredity that determines the traits a person gets from past generations.

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Health-care proxies: A legal document that authorizes someone other than the patient to make decisions for the patient about health issues when necessary.

Hematocrit (HCT): The percentage of red blood cells in the blood.

Hematology: The science that studies the blood; a hematologist is a doctor who specializes in the problems of blood and bone marrow.

Hereditary risk factor: Altered or mutated genes that make it more likely that a person will develop cancer or another disease.

Herpes zoster: A virus that settles around certain nerves causing blisters, swelling, and pain. This condition is also called shingles.

Hormone: A substance that regulates growth, metabolism, and reproduction and is secreted by various organs in the body.

Hormonal therapy: Treatment that prevents cancer cells from growing by taking advantage of the hormonal needs of these cells.

Hospice: A concept of supportive care to meet the special needs of patients and family during the terminal stages of illness. The care may be delivered in the home or hospital by a specially trained team of professionals who provide medical, spiritual and psychological care.

Hyperplasia: An abnormal increase in the number of cells in otherwise normal tissue.

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Immunity (Immune system): The body's ability to fight infections and disease.

Immunosuppression: Weakening of the immune systems causing a lowered ability to fight infection and disease. An immunosuppressant is an agent that diminishes or prevents the immune response. Immunotherapy is the artificial stimulation of the body's immune system to treat or fight disease.

Infiltration: The leaking of fluid or medicines into tissues, which can cause swelling.

Infusion: The delivery of fluids or medications into the bloodstream over a period of time. An infusion device is sometimes used to deliver measured amounts of fluid or medications into the bloodstream over a period of time.

Injection: Pushing a medication into the body with the use of syringe and needle.

In-situ: An early stage of cancer that is localized in one area.

Interferon: A natural chemical released by the body in response to viral infections. Interferon can be artificially produced to activate the immune system; used to fight cancer, it is a form of “biological therapy”.

Interleukin: A natural or artificially produced chemical released by the body.

Intramuscular (IM): an injection into the muscle.

Intravenous: Administration of medication or fluid to a patient by introducing it through a vein.

Invasive: Growing into and destroying normal tissues.

IMRT: Intensity Modulated Radiation Therapy is a type of three dimensional radiation therapy, which improves the targeting of radiation treatments in a way meant to increase the radiation dose to the tumor while decreasing damage to normal tissues.

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Lesion: A lump or abscess that may be caused by injury or disease, such as cancer.

Leukopenia: A low number of white blood cells.

Linear Accelerator: A mega voltage treatment machine capable of delivering high-energy x-ray and, in some instances, an electron beam.

Living will: A document indicating the treatments a person will accept or not accept for use in the event that they are unable to communicate those wishes.

Lymph nodes: Small glands located throughout the body that filter out and destroy bacteria and that can collect cancer cells. A lymphangiogram is a test to look at the lymph nodes.

Lymphatic system: A network that includes lymph nodes and lymph vessels that serve as a filtering system for the blood.

Lymphedema: Swelling either from obstructed cancerous lymph nodes or from surgically removed lymph nodes.

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Malignant: Cancerous.

Malignant tumor: A tumor made up of cancer cells of the type that can spread to other parts of the body. This type of tumor needs treatment.

Mammogram (Mammography): A low-dose x-ray of the breasts to determine whether abnormal growths or cysts are present.

Mastectomy: The surgical removal of the breast.

Mediastinum: The area between the lungs that contains the heart, the windpipe, the esophagus, lymph nodes, nerves, and blood vessels. Mediastinal lymph nodes are lymph nodes located in the chest between the lungs; common site of lung cancer spread.

Medical oncologist: A specialist trained to use medicine to treat cancer.

Metastasis: The spread of cancer from one part of the body to another.

Monoclonal antibodies: Artificially manufactured antibodies specifically designed to find targets on cancer cells for diagnostic or treatment purposes.

MLC: Multi-leaf collimator is a system within the treatment machine, which reduces, or in most cases eliminates the need for custom blocks.

MRI (Magnetic Resonance Imaging): A sophisticated technique to examine the body using powerful electromagnets, radio-frequency waves, and a computer to produce internal pictures of the body.

Mucosa (Mucous membrane): The lining of the mouth and gastrointestinal tract. Mucositis is the inflammation of the lining of the mouth or gastrointestinal tract.

Myelosuppression: A decrease in the production of red blood cells, platelets, and some white blood cells by the bone marrow.

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Nausea: A sensation of needing to vomit.

Needle biopsy: A procedure in which a needle is advanced into a tumor mass in order to obtain a small piece of the tumor.

Neoadjuvant therapy: Treatments such as chemotherapy or combined chemotherapy and radiation therapy given before surgical treatment.

Neoplasm: A new growth of tissue or cells; a tumor that is generally malignant.

Neutropenia: A decreased number of neutrophils, types of white blood cells.

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OCN (Oncology Certified Nurse): A registered nurse who has met requirements and successfully completed a certification exam. An Oncology Clinical Nurse Specialist is a registered nurse with a master’s degree who specializes in the education and treatment of cancer patients.

Oncology: The study and treatment of cancer. Doctors who specialize in oncology are called oncologists.

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P.S.A. (Prostate Specific Antigen): A marker used to determine prostate disease - may be benign or malignant.

Palliative treatment: Treatment aimed at the relief of pain and symptoms of disease but not intended to cure the disease.

Pap (Papanicolaou) smear: The microscopic examination of cells from the vagina or the cervix of the uterus.

Paracentesis: Removing fluid from the abdomen using local anesthesia, a needle, and syringe.

Pathological fracture: A break in a bone usually caused by cancer and some disease condition.

Pathologist: A medical specialist trained to detect the structural changes in tissues and cells caused by disease.

Pathology: The study of disease by the examination of tissues and body fluids under the microscope. A doctor who specializes in pathology is called a pathologist.

Peripheral neuropathy: Functional disturbances of the peripheral nerves sometimes caused by chemotherapy, accounting for symptoms such as numbness and tingling sensations in the hands and toes.

Petechiae: Tiny areas of bleeding under the skin, usually due to a low platelet count.

Photosensitivity: Extreme sensitivity to the sun, leaving the patient prone to sunburns. Some cancer drugs and radiation have this side effect.

Placebo: An inert substance often used in clinical trials for comparison.

Platelets: Cells in the blood that are important for blood clotting. A platelet count refers to the number of platelets in the blood sample.

Pleural effusion: An accumulation of fluid within the pleural cavity, the space between the lungs and the interior walls of the chest.

Port: A device usually implanted under the skin that is used for the infusion of drugs or fluid into the blood stream or for drawing blood for blood tests.

Positron emission tomography (PET Scan): A test that produces an image based on the uptake of glucose by a cancer, used to determine if a tumor is a cancer and if a cancer has spread.

Primary tumor: The original cancer site. For example, breast cancer that has spread to the bone is still called breast cancer.

Progesterone-receptor assay: A test that determines if breast cancer is stimulated by female hormones. Progesterone is one of the female hormones produced by the ovaries.

Prognosis: The likely outcome of a disease, often given in terms of the expected chance of surviving for a certain number of years.

Prophylactic cranial irradiation: Radiation therapy given to the brain in patients with small cell lung cancer to prevent brain metastases from developing.

Prosthesis: Artificial replacement of a missing body part.

Protocol: An action plan for a clinical trial. The plan states what the study will do, how, and why. It explains how many people will be in it, who's eligible to participate, what study agents they'll take, what tests they'll receive and how often, and what information is gathered.

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Radiation oncologist: A medical doctor specializing in the treatment of cancer with radiation.

Radiation Port: The sight on the skin where the radiation enters the body.

Radiation recall: The reoccurrence of a side effect of radiation treatment (such as skin irritation) long after the radiation therapy has been completed.

Radiation therapist: A specially trained technician who administers radiation treatments.

Radiation therapy: Radiation therapy uses high-energy x-rays, either beamed from a machine or emitted by sources implanted in a body part, to kill cancer cells.

Radical mastectomy: Removal of the entire breast along with under-lying muscle and lymph nodes of the armpit.

Radioactive seeds: Small pellets of radioactive material that can be placed into a catheter positioned in an organ of the body. The term “radioactive” refers to the emitting of energy in the form of waves or particles.

Radiologist: A doctor who specializes in the use of x-rays to diagnose and treat disease.

Randomization: A method used to prevent bias in research. People are assigned by chance, often by a computer, either to receive the study agent (intervention group) or not (control group).

Recurrence: The reappearance of cancer after a period of remission.

Red blood cells (erythrocyte): Cells in the blood that bring oxygen to tissues and take carbon dioxide from them.

Red blood count (RBC): The number of red blood cells seen in the blood sample.

Regression: The shrinkage of cancer growth.

Relapse: The re-appearance of cancer.

Remission: Complete or partial disappearance of the signs and symptoms of disease.

Resectable: A cancer that has not grown into any vital structure and can therefore be removed by a surgical procedure.

Risk factor: Anything that increases a person's chance of developing cancer, e.g., smoking.

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Screening: The detection of a disease process before it causes any symptoms.

Segmental mastectomy (lumpectomy): Removal of the lump and a small amount of surrounding breast tissue.

Side effects: Secondary effects of cancer treatment.

Sigmoidoscopy: An examination of the first 10-12 inches of the rectum with a sigmoidoscope (a thin, lighted metal or plastic tube) inserted through the rectum.

Simple mastectomy (modified mastectomy): Removal of the entire breast.

Squamous cell carcinoma: One of the specific types of cancer cells.

Stage: The anatomic extent of a cancer, how far it has spread.

Staging: A method to describe the extent of cancer, using such characteristics as the size of the tumor, lymph node involvement, and where it has spread.

Subcutaneous: Into the fatty tissue under the skin.

Superior vena cava syndrome: Swelling in the head, neck and arms caused by obstruction of the superior vena cava. The superior vena cava is the large vein that drains blood from the head, neck and arms back to the heart, may be blocked by a lung cancer in the upper right lung.

Systemic disease: A disease that affects the whole body instead of a special organ.

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Tattoo: Small permanent marks, placed underneath the superficial layer of skin with the utilization of India ink and a small gauge needle.

Thoracentesis (pleural tap): A procedure to remove fluids from the area between the two layers (pleura) covering the lung.

Three-dimensional conformal radiation therapy: A special method of treating someone with external beam radiation therapy that minimizes exposure of normal tissue to radiation.

Thrombocytopenia: An abnormally low number of platelets (thrombocytes). If the platelets are too few, bleeding may occur.

TNM: An abbreviation for tumor, lymph nodes, and metastases, a method of describing important features about a cancer.

Transfusion: The procedure of giving blood or blood products to a person.

Treatment course: The amount of time necessary to administer therapy based on the Radiation Oncologist’s prescription and the results of treatment planning; typically, this ranges any where from two weeks to up to eight weeks.

Tumor: An abnormal overgrowth of cells. Tumors can be either benign or malignant.

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Ultrasound (Ultrasonography, Sonogram): An examination to locate and measure cystic tumors using very high frequency sound waves, which the human ear cannot hear; sometimes it is used for purposes of diagnosis.

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Vesicant: An intravenous medication that, if leaked into tissues, could cause pain, swelling, tissue damage, and destruction.

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White blood cells (WBC): General term for a variety of cells responsible for fighting invading germs, infections, and allergy-causing agents. Specific white blood cells include granulocytes and lymphocytes.

White blood count (WBC): The actual number of white blood cells seen in a blood sample.

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X-ray: High-energy electromagnetic radiation used to diagnose and treat disease. Diagnostic test using high energy to visualize internal body organs (see radiation therapy).

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