Cancer: Medical Vocabulary

Last Updated June 2023 | This article was created by editorial staff and reviewed by Daron Gersch, MD, FAAFP

When you are diagnosed with cancer, it can be overwhelming. You have your feelings to deal with. But you also have to deal with a whole new cancer medical vocabulary of words you’ve never had to use before.

Path to improved health

The following are terms that you might hear during the diagnosis and treatment of cancer:

Adjuvant therapy: Therapy used to kill remaining cancer cells left behind after primary treatment, usually surgery. Could include chemotherapy, radiotherapy, or hormone therapy.

Advance Directive: Instructions on what kind of care you would like to receive (or not receive) if you become unable to make medical decisions. Includes living wills and do-not-resuscitate (DNR) orders.

Benign: Noncancerous. Any tumor, growth, or cell abnormality that is not cancerous. The growth will not spread to deeper tissues or other parts of the body. Also called nonmalignant.

Biological Therapy: Therapy that uses substances made from living organisms to attack cancer cells. The substances may occur naturally in the body. They also may be made in a laboratory. Some therapies affect the immune system. Others attack specific cancer cells.

Biopsy: Removal of a small portion of tissue to see if it is cancerous.

Carcinoma In Situ (CIS): A group of abnormal cells that remain in the place where they first formed. The cells may become cancer and spread to nearby tissue.

Chemotherapy: Therapy that uses special medicines to damage and kill cancer cells.

Clinical Trials: Research studies that involve actual patients. They help find better ways to manage cancer (and other medical conditions). They study prevention, detection, diagnosis, and treatment.

Colonoscopy: Insertion of a long, flexible, lighted tube through the rectum and into the colon. This allows the doctor to check the lining of the colon for abnormalities.

Colposcopy: Procedure where a lighted, magnifying instrument (colposcope) is used to look for problems in the vagina and cervix.

Complementary and Alternative Medicine (CAM): Therapy used during or after cancer treatment to help relieve the symptoms of cancer or standard treatments. Examples include meditation, yoga, spiritual counseling, acupuncture, and transcutaneous electrical nerve stimulation (TENS).

Hormone therapy: Treatment that adds, removes, or blocks hormones to slow the growth of cancer cells.

Hospice Care: Hospice care is a special program for patients who are ill and dying, and their families. It is a form of palliative care. It is meant for people who have 6 months or less to live.

Immunotherapy: A type of biological therapy. It stimulates or suppresses the immune system to help the body fight cancer.

Invasive Cancer: Cancer that starts in one area of the body and spreads to surrounding tissue. Also called infiltrating cancer.

Leukemia: Cancer of bone marrow and blood.

Localized: Cancer that is confined to a certain area and has not spread.

Lymph nodes: Small, bean-shaped organs that help fight infection and disease. They are part of the lymphatic system. Clusters of nodes are found in different areas, including the neck, underarm, abdomen, and groin.

Lymphatic system: A network of tissues and organs that produce, store, and carry white blood cells. These cells fight infection and disease. It includes the bone marrow, spleen, lymph nodes, and lymphatic vessels. Cancer can use this system to spread to other parts of the body.

Lymphoma: Cancer that begins in the cells of the immune system.

Lumpectomy: Surgery that removes abnormal or cancerous tissue in the breast.

Malignant: Cancerous. Cancer cells are present in a tumor and may spread to other parts of the body.

Mammogram: An X-ray taken of the breast in order to check for abnormalities.

Mastectomy: Surgery to remove all or part of the breast.

Melanoma: A form of cancer that begins in melanocytes. These are cells that make the pigment melanin. It can begin in a mole on the skin or in other tissues with pigment. These include the eye or intestines.

Metastasis: The spread of cancer cells from where they first formed to another area of the body. Cancer cells break away from the primary tumor. They travel through the blood or lymphatic system to other areas. For example, breast cancer cells may spread to the lymph nodes, or lung cancer cells may travel to the brain.

Neoadjuvant Therapy: Treatment given to shrink a tumor before the main treatment (usually surgery) is given. Often includes chemotherapy or radiation.

Nonmelanoma: A type of skin cancer where the cancerous cells are found in places other than the melanocytes.

Oncologist: A doctor who specializes in cancer and its treatment.

Oncology: The study of cancer.

Palliative Care: Therapy that focuses on improving one’s quality of life rather than curing his or her cancer.

Pap Smear: A test that involves the scraping and study of cells that line the cervix. They are used to detect precancerous and cancerous cells. They are also called pap tests.

Pathologist: A doctor who identifies diseases by studying cells under a microscope.

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

Precancerous: Refers to cells that have the potential to become cancerous.

Prognosis: The expected outcome of a disease and chances for recovery.

Prosthesis: An artificial replacement for a body part such as a breast or leg.

Prostate Specific Antigen (PSA) Test: Measures the amount of a protein in the blood. The protein is created by the prostate gland. An elevated amount could be the result of infection, an enlarged prostate, or prostate cancer.

Radiation Therapy: Uses high-energy rays or radioactive materials to damage or kill cancer cells.

Reconstructive Surgery: Repairs skin and muscles after cancer surgery has been performed. Often used to rebuild a breast after a mastectomy.

Recurrence: The development of cancerous cells after cancer treatment. Could be in the same area or another part of the body

Remission: When the signs and symptoms of cancer decrease or disappear, but cancer may still be in the body. Can be temporary or permanent.

Sarcoma: A cancer that develops in the tissues that support and connect the body. These include fat, muscle, and cartilage.

Stages of Cancer: A way of describing the extent of cancer in the body. It is usually based on the size of the tumor, whether lymph nodes contain cancer, and whether the cancer has spread to other areas of the body.

Tumor: An abnormal mass of tissue that forms when normal cells begin to change and grow abnormally. It can be benign (not cancer) or malignant (cancer). It can also be called a nodule, mass, or neoplasm.

Things to consider

These are just a few of the terms you may hear in your doctor’s office if you have cancer. If your doctor ever uses a word you don’t understand, ask him or her what it means. You can also look online for lists of common words related to cancer. The National Cancer Institute’s list has more than 8,000 words in its online database.

Questions to ask your doctor

  • I don’t know what all of these words mean. Can you tell me?
  • Do you have a handout you can give me that explains some of these concepts?
  • Where else can I go for help in understanding my cancer diagnosis?


National Cancer Institute: Dictionary of Cancer Terms

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