En Español

Cancer terms

Use the list below of common words related to cancer to better understand your cancer diagnosis and treatment

From the National Cancer Institute (NCI) 

The information below is based on information originally published by the National Cancer Institute (NCI), the US government’s main agency for cancer research. This page is meant to be an educational guide. Always consult with your health care team.



Not normal. Describes a state, condition, or behavior that is unusual or different from what is considered normal.

Adjuvant therapy

Additional cancer treatment given after the primary treatment to lower the risk that the cancer will come back. May include chemotherapy, immunotherapy, radiation therapy, hormone therapy, or targeted therapy.

Adrenal gland

Two small glands on top of the kidneys that make adrenaline, noradrenaline, and steroid hormones. These help control heart rate, blood pressure, and other important body functions.


A condition in which the number of red blood cells is below normal, that can cause fatigue, shortness of breath, dizziness, a fast heartbeat and/or pale skin. Cancer treatments, including chemotherapy and radiation, can cause anemia.



Not cancer. Benign tumors may grow larger but do not spread to other parts of the body. Also called nonmalignant.


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.


The removal of cells or tissues for examination by a pathologist.


A type of radiation therapy in which radioactive material sealed in needles, seeds, wires, or catheters is placed directly into or near a tumor.



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.

Cancer subtype

Describes the smaller groups that a type of cancer can be divided into, based on certain characteristics of the cancer cells. These characteristics include how the cancer cells look under a microscope and whether there are certain substances in or on the cells or certain changes to the DNA of the cells. It is important to know the subtype of a cancer in order to plan treatment and determine prognosis.


Cancer that begins in the skin or in the tissues that line or cover internal organs.


In biology, the smallest unit that can live on its own and that makes up all living organisms and the tissues of the body.


Treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing.

Clinical trial

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.

CT scan

A procedure that uses a computer linked to an x-ray machine to make a series of pictures of the areas inside the body. The pictures are taken from different angles and are used to create 3-dimensional (3-D) views of tissues and organs.



The process of identifying a disease, condition, or injury from its signs and symptoms.



Effectiveness. In medicine, the ability of an intervention (for example, a drug or surgery) to produce the desired beneficial effect.


The layer of tissue that lines the uterus.



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.



In medicine, a process that makes pictures of areas inside the body. Imaging uses methods such as x-rays (high-energy radiation), ultrasound (high-energy sound waves), and radio waves.

Immune system

A complex network of cells, tissues, organs, and the substances they make that helps the body fight infections and other diseases.


A type of therapy that uses substances to stimulate or suppress the immune system to help the body fight cancer, infection, and other diseases.

In situ

In its original place. For example, the phrase carcinoma in situ means abnormal cells have not spread and are found only in the place where they first formed.


Use of a syringe and needle to push fluids or drugs into the body; often called a “shot.”

Intravenous (IV)

Into or within a vein. Intravenous usually refers to a way of giving a drug or other substance through a needle or tube inserted into a vein. Also called IV.


Laparoscopic surgery

Surgery done with the aid of a laparoscope. A laparoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue to be checked under a microscope for signs of disease.

Lymph node

A small bean-shaped structure that is part of the body’s immune system. Lymph nodes filter substances that travel through the lymphatic fluid, and they contain lymphocytes (white blood cells) that help the body fight infection and disease.


Cancer that begins in the cells of the immune system.



A term used to describe cancer. Malignant cells grow in an uncontrolled way and can invade nearby tissue and spread to other parts of the body.


In medicine, a lump in the body. It may be caused by the abnormal growth of cells, a cyst, hormonal changes, or an immune reaction. A mass may be benign (not cancer) or malignant (cancer).


To spread from one part of the body to another. When cancer cells metastasize and form secondary tumors, the cells in the metastatic tumor are like those in the original (primary) tumor.


A procedure that uses radio waves, a powerful magnet, and a computer to make a series of detailed pictures of areas inside the body. It may be used to help diagnose disease, plan treatment, or find out how well treatment is working.


Neoadjuvant therapy

Treatment given as a first step to shrink a tumor before the main treatment, which is usually surgery. Examples include chemotherapy, immunotherapy, radiation therapy, and hormone therapy.



By or having to do with the mouth.


Palliative care

Care given to improve the quality of life and help reduce pain in people who have a serious or life-threatening disease, such as cancer. The goal of palliative care is to prevent or treat, as early as possible, the symptoms of a disease and the side effects caused by treatment of the disease. It also attends to the psychological, social, and spiritual problems caused by the disease or its treatment.

PET scan

An imaging test in which a small amount of radioactive glucose (sugar) is injected into a vein, and a scanner is used to make detailed, computerized pictures of areas inside the body where the glucose is taken up. Cancer cells often take up more glucose than normal cells, so the pictures can show cancer cells in the body. Also called a positron emission tomography scan.


A molecule made up of amino acids. Proteins are needed for the body to function properly.


Radiation therapy

The use of high-energy radiation from x-rays, gamma rays, neutrons, protons, and other sources to kill cancer cells and shrink tumors.

Recurrent cancer

Cancer that has come back, usually after a period of time when no cancer was detected. The cancer can return to the same place as the original tumor or to another place in the body.



A type of cancer that begins in bone or in the soft tissues of the body, including cartilage, fat, muscle, blood vessels, fibrous tissue, or other connective or supportive tissue. Different types of sarcoma are based on where the cancer forms. For example, osteosarcoma forms in bone, and liposarcoma forms in fat. Sarcoma occurs in both adults and children.

Side effect

A problem that occurs when treatment affects healthy tissues or organs. Some common side effects of cancer treatment are nausea, vomiting, fatigue, pain, hair loss, and mouth sores.


In medicine, a doctor or other health care professional who is trained and licensed in a specific area of practice. Examples include oncologists (cancer specialists) and hematologists (blood specialists).


The extent of a cancer in the body. Staging is usually based on the size of the tumor, whether lymph nodes contain cancer, and whether the cancer has spread from the original site to other parts of the body.

Stem cell transplant

A procedure in which a patient receives healthy stem cells (blood-forming cells) to replace their own stem cells that have been destroyed by treatment with radiation or high doses of chemotherapy.


A procedure to remove or repair a part of the body or to find out whether disease is present. Also called operation.


The experience of survivorship focuses on the physical, mental, emotional, social, and financial effects of a person with cancer from the time of diagnosis until the end of life. This includes follow-up care, late effects of treatment, cancer recurrence, second cancers, and quality of life. Family members, friends, and caregivers are also considered part of the survivorship experience.


A physical or mental problem that a person experiences that may indicate a disease or condition. Symptoms cannot be seen and do not show up on medical tests.


Targeted therapy

A type of treatment that uses drugs or other substances to identify and attack specific types of cancer cells with less harm to normal cells.


 On the surface of the body.


An abnormal mass of tissue that forms when cells grow and divide more than they should or do not die when they should. Tumors may be benign (not cancer), or malignant (cancer).



A procedure that uses high-energy sound waves to look at tissues and organs inside the body.

Sign up for updates

Be the first to know when new information and articles become available.

Register now