Understanding cancer terminology

Expert reviewer, Dr Adam Dangoor, Consultant Medical Oncologist
Next review due December 2022

Cancer is when your cells begin to grow in an uncontrolled way and spread into other tissues; it can start almost anywhere in your body. If you have cancer, you may hear medical terms that you don’t understand. So, we’ve put together a list of some common cancer terminology and abbreviations with explanations of what they mean.

A - D

Adjuvant therapy

This is a treatment that you have after your initial treatment for cancer. For example, chemotherapy after surgery. The aim of adjuvant therapy is to try to reduce the chance of the cancer coming back. Adjuvant therapies include chemotherapy, radiotherapy, hormone therapy and biological therapy. See also ‘Neoadjuvant therapy’ below.

Advanced cancer

If your doctor describes your cancer as 'advanced', it usually means that it's spread from where it started to another part of your body. Locally advanced cancer usually means that the cancer has grown from where it started into nearby body tissues or lymph glands. See our section on ‘Stage’ below to find out more.

Aggressive cancer

This is an informal term rather than a medical one. If your doctor describes your cancer as aggressive, it means it tends to grow or spread quite quickly. The medical term that describes how quickly or slowly a cancer is likely to grow is ‘grade’. See our section ‘Grade’ below for more information on this.

Benign

If your tumour (growth of cells) is described as benign, this means it isn’t cancer. Benign tumours usually grow quite slowly and don’t spread. They usually only cause problems if they become very large or press on other organs in your body. They also affect you if they take up space inside your skull or release hormones (because hormones affect how your body functions). A malignant tumour on the other hand is cancerous and may grow and spread. See our section ‘Malignant’ below for more information on this.

Biological therapy

These are treatments that are (or are developed from or mimic) natural substances produced from living things. Biological therapies may act on cancer cells directly to kill them or act to stop them growing. Alternatively, these therapies may help your immune system to fight back against cancer cells. Types of biological therapy include monoclonal antibodies, cancer growth inhibitors, vaccines, gene therapy and immunotherapy. These work in different ways. For example, some change how cancer cells send growth signals to each other, some stop cancers from growing new blood vessels.

Biopsy

This is a small sample of tissue taken from your tumour, either during surgery or using a needle. A pathologist is a doctor who specialises in examining samples of tissue to help diagnose diseases. They’ll examine the sample under a microscope to see if it contains any cancer cells and if so, what type.

Carcinogen

Something that’s known to cause cancer is called a carcinogen. Tobacco smoke is an example. But not everybody who is exposed to a carcinogen gets cancer. This means other things such as your age, diet and genetic make-up can play a part.

Carcinoma

Carcinomas are types of cancer that start in the cells of your skin or the tissues that cover and line the body cavities and organs. Most cancers are carcinomas.

Carcinoma in situ

This means abnormal cells are only found in the place where they started growing in the body. They haven’t spread to anywhere else. Also called stage 0 cancer. These abnormal cells may become cancer and spread into nearby tissue if not treated.

Chemotherapy

Chemotherapy is treatment with drugs that kill cancer cells. Chemotherapy or ‘chemo’ works by killing cells that are dividing. Cancer cells divide more often than normal cells.

E - H

Early-stage cancer

Early-stage cancer is early in its development and may not have spread to other parts of the body. What’s considered to be early stage differs between different types of cancer.

Endocrine therapy

Endocrine is another word for hormone – endocrine therapy and hormone therapy are the same. Endocrine therapy adds or blocks the production of a hormone in your body or stops a hormone from working. See our section ‘Hormone therapy’ below for more information.

False-positive test result

This is a test result that suggests you have a disease or condition when you don’t actually have it. This happens occasionally because no test is perfect but good tests have a low rate of false-positive results. If signs of cancer are detected by a test, your doctor will give you more tests to confirm the diagnosis.

Grade

This term describes how cancer cells look under a microscope. The more abnormal they are, the higher the grade. Low-grade cancers tend to grow more slowly and be less likely to spread. Some types of cancer have their own grading systems but cancer is most often graded from 1 (low grade) to 3 (high grade).

Hormone therapy

Hormone therapy adds or blocks the production of a hormone in your body or stops a hormone from working. Examples include treatment that blocks testosterone production in prostate cancer and treatment that stops oestrogen from working in breast cancer. Hormone therapy is also called endocrine therapy.

I - L

Immunotherapy

This is a biological therapy that uses the immune system to fight cancer. See our section ‘Biological therapy’ above for more information on this.

Leukaemia

This term describes a cancer of white blood cells that starts in the tissue that forms blood, such as bone marrow. There are several different types of leukaemia, which affect different types of white blood cell.

Lymphoma

This is a cancer that starts in cells of your lymphatic system – a network of lymph glands that contain white cells linked by a network of tubes known as lymphatic channels. There are two main types of lymphoma: Hodgkin lymphoma and non-Hodgkin lymphoma.

Lymph glands (nodes)

Lymph glands are found throughout your body and are part of your immune system. Cancer can spread to your lymph nodes from a cancer that started somewhere else in your body.

M - P

Malignant

Another word for cancer or cancerous; it is the opposite of benign. A malignant tumour (cancer) grows more quickly than a benign tumour and can spread to other parts of your body.

Melanoma

This type of cancer starts in pigment cells in your skin (melanocytes). Melanoma is the most serious form of skin cancer but can often be cured if it’s removed before the cancer cells have spread.

Metastatic cancer

This term describes cancer that has spread from one part of the body to another. It’s also called secondary cancer.

Myeloma

Myeloma is a type of bone marrow cancer that starts in cells called plasma cells.

Neoadjuvant therapy

This is treatment you have before your main treatment, which is usually surgery. Neoadjuvant therapy aims to shrink the cancer so it is easier to remove; it also helps to reduce the risk of the cancer coming back. Neoadjuvant therapies include chemotherapy, radiotherapy and hormone therapy.

Neoplasm

Neoplasm is the scientific name for an abnormal lump of cells (a tumour). A neoplasm can be non-cancerous (benign) or cancer (malignant).

Palliative care

Also known as supportive care, palliative care is treatment designed to help control symptoms and improve quality of life. Palliative care is often used to mean ‘treatment for people whose illness can’t be cured’, but this isn’t necessarily the case.

Personalised medicine

Treatment that’s tailored to the biology of your specific cancer is called personalised medicine. Genetic testing of cancer cells and normal cells helps doctors customise your treatment to your individual needs. Many biological therapies can be used as part of personalised medicine. See our section on ‘Biological therapy’ above for more information on this.

Primary cancer

Where the cancer originally started in your body. If a cancer has spread, this is a secondary cancer. So, lung cancer that has spread to your liver is primary lung cancer with secondary cancer in your liver. See ‘Secondary cancer’ below to find out more.

Prognosis

This term means the likely outcome of your cancer. It could refer to your chance of recovery, the likelihood of your cancer coming back or, if your chance of survival is low, how long you might expect to live for.

Q - T

Quality of life

Your quality of life is your overall enjoyment of life and sense of wellbeing, and your ability to carry out normal activities in your daily life.

Radiotherapy

Radiotherapy uses high energy radiation such as X-rays, gamma rays or protons to kill cancer cells. You most often have radiotherapy treatment from a machine outside the body. However, it can also be delivered internally from implants (this is called brachytherapy) or by radioactive injections or drugs.

Remission

When a cancer is in remission, there’s no sign of it in examinations or tests. Doctors tend to talk about remission instead of cure because cancers can sometimes come back. In a partial remission, some but not all, signs and symptoms have gone.

Sarcoma

A sarcoma is a type of cancer that starts in the cells of bone or other tissues that support your body. These tissues include muscle, blood vessels, cartilage and fibrous tissues.

Secondary cancer

A cancer that has spread from where it started is called a secondary cancer. Some of the most common places for secondary cancers are the bones, liver and lungs. Where a cancer is most likely to spread depends on what type of primary cancer it is. See also ‘Primary cancer’ above.

Stage

Doctors use a system of ‘stages’ to describe the size of your cancer, how far it has grown and if it has spread. This helps your doctor to choose the best treatment for you. There are usually four stages.

Stage one means the cancer is small and hasn’t grown deeply into nearby tissues or spread to the lymph nodes or other parts of the body. This is also called early-stage cancer. See ‘Early stage cancer’ above to find out more.
Stages two and three are larger cancers that have grown more deeply into nearby tissue and may have also spread to lymph nodes but not to other parts of the body.
Stage four means the cancer has spread to other parts of the body.

There are other staging systems such as the TNM classification – see our section on ‘TNM’ below for more information.

Cancers are also graded (usually from 1 to 3). This describes how cancer cells look under a microscope not the size and spread that staging describes. The more abnormal the cells are, the higher the grade. See our section ‘Grade’ above for more information.

Systemic therapy

This refers to a treatment that travels through the bloodstream and so reaches your whole body. All drug treatments that are injected or that you take by mouth are systemic, including chemotherapy, biological therapy and hormone therapy.

Targeted therapy

Targeted therapy is a treatment that directly targets cancer cells to stop them from growing and spreading. Targeted treatments are a type of biological therapy. See our section ‘Biological therapy’ above to find out more.

TNM classification

A staging system to describe cancer. It includes the size of the tumour (T), if any lymph nodes are affected (N) and if the cancer has spread to other parts of the body (metastasised – M).

Tumour

A lump of cells that may or may not be cancerous (malignant or benign). A tumour is also known as a Neoplasm. See also our section on ‘Neoplasm’ above.

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Other helpful websites
- Cancer Research UK
  0808 800 4040
  www.cancerresearchuk.org
- Macmillan Cancer Support
  0808 808 0000
  www.macmillan.org.uk
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Author information

Reviewed by Rachael Mayfield-Blake, Freelance Health Editor, December 2019
Expert reviewer, Dr Adam Dangoor, Consultant Medical Oncologist
Next review due December 2022