Glossary of Cancer Terms

In reading about cancer, you may come across a number of unfamiliar terms. This glossary, adapted from the National Cancer Institute of the National Institutes of Health, can help you decipher some of them. For more information, read about "Reduce Cancer Risk" "Cancer: What It Is" "Cancer Treatments" "Cancer Check-ups." For a list of individual cancers, see "Cancer: What It Is." For additional questions, of course, ask your doctor.

Acute: Having the abrupt onset of symptoms and a short course - not chronic.

Adenoma: A noncancerous tumor, of glandular tissues.

Adjuvant therapy: Treatment given after the primary treatment to increase the chances of a cure. Adjuvant therapy may include chemotherapy, radiation therapy or hormone therapy. (Read about "Radiation Therapy")

Aggressive: A fast-growing cancer.

Angiogenesis: Blood vessel formation. Tumor angiogenesis is the growth of blood vessels from surrounding tissue to a solid tumor. This is caused by the release of chemicals by the tumor.

Antibody therapy: Treatment with an antibody, a substance that can directly kill specific tumor cells or stimulate the immune system to kill tumor cells. (Read about "The Immune System")

Aspiration: Removal of fluid from a cyst or cells from a lump, using a needle and syringe.

Atypical hyperplasia: Cells that are both abnormal (atypical) and increased in number. They may also be precancerous.

Average risk: A measure of the chances of getting cancer without the presence of any specific factors known to be associated with the disease.

Benign: Not cancerous - cannot invade neighboring tissues or spread to other parts of the body.

Biological therapy: Treatment to stimulate or restore the ability of the immune system to fight infection and disease. Also known as immunotherapy, biotherapy or biological response modifier (BRM) therapy. (Read about "The Immune System")

Biomarkers: Substances sometimes found in an increased amount in the blood, other body fluids, or tissues and that may suggest the presence of some types of cancer.

Biopsy: The removal of a sample of tissue or cells for examination under a microscope for purposes of diagnosis. (Read about "Biopsy")

Brachytherapy: A procedure in which radioactive material sealed in needles, seeds, wires or catheters is placed directly into or near a tumor. Also called internal radiation, implant radiation or interstitial radiation therapy. (Read about "Radiation Therapy")

Cancer: A general name for more than 100 diseases in which abnormal cells grow out of the body's control. Cancer cells can invade and destroy healthy tissues, and they can spread through the bloodstream and the lymphatic system to other parts of the body.

Carcinoma: Cancer that begins in tissues lining or covering the surfaces (epithelial tissues) of organs, glands, or other body structures. Most cancers are carcinomas.

Carcinoma in situ: A group of abnormal cells that remain in the location where they form. They may develop into invasive cancer.

Chemoprevention: The use of drugs or vitamins to prevent cancer in people who have precancerous conditions or a high risk of cancer, or to prevent the recurrence of cancer in people who have already been treated for it. (Read about "Vitamins & Minerals")

Chromosomes: Structures located in the nucleus of a cell, containing genes. (Read about "Genetics")

Computed tomography (CT) scanning: An imaging technique that uses a computer to organize the information from multiple x-ray views and construct a cross-sectional image of areas inside the body. (Read about "CT Scan - Computerized Tomography")

Core needle biopsy: The use of a small cutting needle to remove a core of tissue for microscopic examination. (Read about "Biopsy")

Cyst: Fluid-filled sac.

Excisional biopsy: The surgical removal (excision) of an abnormal area of tissue, usually along with a margin of healthy tissue, for microscopic examination. (Read about "Biopsy")

False negative: Test results reported as negative even though abnormality is present.

False positive: Test results that indicate falsely cancer is present when the disease is truly absent.

Fine needle aspiration: The use of a slender needle to remove fluid from a cyst or clusters of cells from a solid lump.

Frozen section: A sliver of frozen biopsy tissue. A frozen section provides a quick preliminary diagnosis but is not 100 percent reliable. It is always followed by a permanent section examination by a pathologist. (Read about "Biopsy")

Gene: Segment of a DNA molecule and the fundamental biological unit of heredity.

Genetic change: An alteration in a segment of DNA, which can disturb a gene's behavior and sometimes leads to disease.

Higher risk: A measure of the chances of getting cancer when factor(s) known to be associated with the disease are present.

Hormones: Chemicals produced by various glands in the body, which produce specific effects on specific target organs and tissues.

Hyperplasia: Excessive growth of cells.

Incisional biopsy: The surgical removal of a portion of an abnormal area of tissue, by cutting into (incising) it, for microscopic examination. (Read about "Biopsy")

Infection: Invasion of body tissues by microorganisms that cause disease such as various bacteria and viruses. (Read about "Microorganisms")

Infiltrating cancer: Cancer that has spread to nearby tissue, lymph nodes or other parts of the body. (Same as Invasive cancer.)

Inflammation: The body's protective response to injury (including infection). Inflammation is marked by heat, redness, swelling, pain and loss of function.

Invasive cancer: Cancer that has spread to nearby tissue, lymph nodes or other parts of the body. (Same as Infiltrating cancer.)

Lymphatic system: The tissues and organs that produce, store, and transport cells that fight infection and disease. (Read about "The Lymph System")

Magnetic resonance imaging (MRI): A technique that uses a powerful magnet linked to a computer to create detailed pictures of areas inside the body. (Read about "MRI - Magnetic Resonance Imaging")

Malignancy: State of being cancerous. Malignant tumors can invade surrounding tissues and spread to other parts of the body.

Margin: The edge or border of the tissue removed in cancer surgery. The margin is described as negative or clean when the pathologist finds no cancer cells at the edge of the tissue, suggesting that all of the cancer has been removed. The margin is described as positive or involved when the pathologist finds cancer cells at the edge of the tissue, suggesting that not all of the cancer has been removed.

Monoclonal antibody: Laboratory-produced substances that can locate and bind to cancer cells wherever they are in the body. Many monoclonal antibodies are used in cancer detection or therapy; each one recognizes a different protein on certain cancer cells. Monoclonal antibodies can be used alone, or they can be used to deliver drugs, toxins or radioactive material directly to a tumor.

Mutation: A change in the number, arrangement or molecular sequence of a gene.

Needle biopsy: Use of a needle to extract cells or bits of tissue for microscopic examination. (Read about "Biopsy")

One-step procedure: Biopsy and surgical treatment combined into a single operation. (Read about "Biopsy")

Palpation: Use of the fingers to press body surfaces, so as to feel tissues and organs underneath.

Pathologist: A doctor who diagnoses disease by studying cells and tissues under a microscope.

Permanent section: Biopsy tissue specially prepared and mounted on slides so that it can be examined under a microscope by a pathologist. (Read about "Biopsy")

Phytochemicals: Naturally occurring chemicals found in plants that may be important nutrients for reducing a person's cancer risk.

Positron emission tomography (PET scanning): A technique that uses signals emitted by radioactive tracers to construct images of the distribution of the tracers in the human body.(Read about "PET - Positron Emission Tomography")

Rad: A unit of measure for radiation. It stands for radiation absorbed dose. Now usually expressed as Gray units (Gy). One Gy equals 100 rad. (Read about "Radiation Therapy")

Radiation: Energy carried by waves or by streams of particles. Various forms of radiation can be used in low doses to diagnose disease and in high doses to treat disease. (Read about "X-rays" "Radiation Therapy")

Radiologist: A doctor with special training in the use of diagnostic imaging such as CT, MRI, PET and ultrasound, to image body tissues and to treat disease. (Read about "CT Scan - Computerized Tomography" "MRI - Magnetic Resonance Imaging" "PET - Positron Emission Tomography" "Ultrasound Imaging")

Risk: A measure of the likelihood of some uncertain or random event with negative consequences for human life or health.

Risk factors (for cancer): Conditions or agents that increase a person's chances of getting cancer. Risk factors do not necessarily cause cancer; rather, they are indicators, statistically associated with an increase in likelihood.

Sonogram: The image produced by ultrasound equipment. (Read about "Ultrasound Imaging")

Specimen x-ray: An x-ray of tissue that has been surgically removed (surgical specimen). (Read about "X-rays")

Surgical biopsy: The surgical removal of tissue for microscopic examination and diagnosis. Surgical biopsies can be either excisional or incisional. (See Excisional biopsy and Incisional biopsy.) (Read about "Biopsy")

Tumor: An abnormal growth of tissue. Tumors may be either benign or cancerous.

Tumor markers: Proteins (either amounts or unique variants) made by altered genes in cancer cells that are involved in the progression of the disease.

Two-step procedure: Biopsy and treatment done in two stages, usually a week or two apart. (Read about "Biopsy")

Ultrasound: The use of sound waves to produce images of body tissues. (Read about "Ultrasound Imaging")

X-ray: A high-energy form of radiation. X-rays form an image of body structures by traveling through the body and striking a sheet of film or digital plate. (Read about "X-rays")

Used with permission of the National Institutes of Health.

More Cancer Information:

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For a list of individual types of cancer, see Cancer: What It Is