Cancer Terms

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  • Acute

    Refers to symptoms that start and worsen quickly but do not last over a long time.

  • Benign

    Refers to a tumor that is not cancerous. The tumor does not usually invade nearby tissue or spread to other parts of the body.

  • Biopsy

    The removal of a small amount of tissue for examination under a microscope. Other tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis. Learn more about biopsy.

  • Bone marrow

    The soft, spongy tissue found in the center of large bones where blood cells are formed.

  • Cancer

    A group of more than 100 different diseases that can begin almost anywhere in the body, characterized by abnormal cell growth and the ability to invade nearby tissues. Learn more about the basics of cancer.

  • Carcinoma

    Cancer that starts in skin or tissues that line the inside or cover the outside of internal organs.

  • Cells

    The basic units that make up the human body.

  • Chemoprevention

    The use of natural, synthetic (made in a laboratory), or biologic (from a living source) substances to reverse, slow down, or prevent the development of cancer. Learn more about chemoprevention.

  • Chemotherapy

    The use of drugs to kill cancer cells. Learn more about chemotherapy.

  • Chronic

    Refers to a disease or condition that persists, often slowly, over a long time.

  • Imaging test

    A procedure that creates pictures of internal body parts, tissues, or organs to make a diagnosis, plan treatment, find out whether treatment is working, or observe a disease over time.

  • In situ

    In place. Refers to cancer that has not spread to nearby tissue, also called non-invasive cancer.

  • Invasive cancer

    Cancer that has spread outside the layer of tissue in which it started and has the potential to grow into other tissues or parts of the body, also called infiltrating cancer.

  • Laboratory test

    A procedure that evaluates a sample of blood, urine, or other substance from the body to make a diagnosis, plan treatment, check whether treatment is working, or observe a disease over time.

  • Leukemia

    A cancer of the blood. Leukemia begins when normal white blood cells change and grow uncontrollably. 

  • Localized cancer

    Cancer that is confined to the area where it started and has not spread to other parts of the body.

  • Lymphatic system

    A network of small vessels, ducts, and organs that carry fluid to and from the bloodstream and body tissues. Through the lymphatic system, cancer can spread to other parts of the body.

  • Lymphoma

    A cancer of the lymphatic system. Lymphoma begins when cells in the lymph system change and grow uncontrollably. Sometimes a tumor is formed.

  • Malignant

    Refers to a tumor that is cancerous. It may invade nearby healthy tissue or spread to other parts of the body.

  • Mass

    A lump in the body.

  • Metastasis

    The spread of cancer from the place where the cancer began to another part of the body. Cancer cells can break away from the primary tumor and travel through the blood or the lymphatic system to the lymph nodes, brain, lungs, bones, liver, or other organs.

  • Oncologist

    A doctor who specializes in treating people with cancer. The five main types of oncologists are medical, surgical, radiation, gynecologic, and pediatric oncologists. Learn more about the types of oncologists.

  • Oncology

    The study of cancer.

  • Pathologist

    A doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease.

  • Polyp

    A growth of normal tissue that usually sticks out from the lining of an organ, such as the colon.

  • Precancerous

    Refers to cells that have the potential to become cancerous. Also called pre-malignant.

  • Predisposition

    A tendency to develop a disease that can be triggered under certain conditions. For example, although a genetic predisposition to cancer increases a person's risk of developing cancer, it is not certain that the person will develop it. Learn more about genetics.

  • Primary cancer

    Describes the original cancer.

  • Prognosis

    Chance of recovery; a prediction of the outcome of a disease. Learn more about survival statistics used to estimate a patient’s prognosis.

  • Sarcoma

    A cancer that develops in the tissues that support and connect the body, such as fat and muscle. Learn more about sarcoma.

  • Screening

    The process of checking whether a person has a disease or has an increased chance of developing a disease when the person has no symptoms.

  • Secondary cancer

    Describes either a new primary cancer (a different type of cancer) that develops after treatment for the first type of cancer, or cancer that has spread to other parts of the body from the place where it started (see metastasis, above).

  • Staging

    A way of describing cancer, such as where it is located, whether or where it has spread, and whether it is affecting the functions of other organs in the body. Learn more about stages of cancer.

  • Tumor

    A mass formed when normal cells begin to change and grow uncontrollably. A tumor can be benign (noncancerous) or malignant (cancerous, meaning it can spread to other parts of the body). Also called a nodule or mass.