5-year prevalence
The number of living people who were diagnosed with cancer in the last 5 years.
Source: NCI, 2026
Glossary
Words, explained simply
Across the site, words underlined with dots are explained with one click.
5-year survival
The share of people still alive 5 years after diagnosis. Many live much longer.
Source: ACS, 2026
Adjuvant treatment
Treatment given after surgery to reduce the risk of the cancer coming back.
Source: NCI, 2026
Age-standardised rate
A rate calculated as if all countries had the same age pyramid. It makes it possible to compare young and old countries.
Source: IARC, GLOBOCAN, 2024
Aromatase inhibitor
A hormone therapy medicine that lowers the amount of oestrogen in the body. Mainly used after menopause.
Source: NCI, 2026
Benign
Not cancer. A benign lump does not spread through the body.
Source: NCI, 2026
Biopsy
Taking a small piece of the lump, often with a needle, to analyse it under the microscope.
Source: ACS, 2026
Bone scan
A test using a weakly radioactive product that shows whether the cancer has reached the bones.
Source: NCI, 2026
Brachytherapy
Radiotherapy in which the radiation source is placed very close to the area to be treated.
Source: NCI, 2026
BRCA1 and BRCA2
Two genes that help repair DNA. A change in these genes, passed down in families, sharply increases the risk of breast and ovarian cancer.
Source: NCI, 2026
Cancer
A disease in which cells multiply without control. They can invade nearby tissue and spread elsewhere in the body.
Source: NCI, 2026
Carcinoma
Cancer that starts in the cells lining organs. Most breast cancers are carcinomas.
Source: NCI, 2026
Chemotherapy
Medicines that destroy cells that divide quickly, including cancer cells. Given by drip or as tablets.
Source: NCI, 2026
Clinical breast exam
An examination of the breasts and armpits done by hand by a doctor, midwife or trained nurse.
Source: NCI, 2026
CT scan
An X-ray test that produces cross-section images of the body. It is used to look for metastases.
Source: NCI, 2026
Ductal carcinoma
Cancer that starts in the ducts that carry milk. It is the most common form.
Source: ACS, 2026
Early diagnosis
Recognising the signs quickly and seeing a doctor quickly, so the cancer is found while it is still small.
Source: WHO, 2023
Grade (SBR)
A score that says how much the cancer cells look like normal cells or not. A high grade means faster growth.
Source: ACS, 2026
HER2
A protein that pushes cells to multiply. When there is too much of it, the cancer is called “HER2-positive”. Targeted treatments exist.
Source: ACS, 2026
Hormone receptors (ER, PR)
“Locks” on the surface of cells to which oestrogen (ER) or progesterone (PR) attach.
Source: ACS, 2026
Hormone therapy
Treatment that blocks the effect of hormones on cancer cells. Often taken as tablets for 5 to 10 years.
Source: NCI, 2026
Hormone-sensitive (HR+)
Cancer whose growth is stimulated by female hormones (oestrogen, progesterone). It can be treated with hormone therapy.
Source: ACS, 2026
Immunohistochemistry (IHC)
A test done on the biopsy to find out whether the cancer has hormone receptors and the HER2 protein. It guides the choice of treatment.
Source: ACS, 2026
Immunotherapy
Treatment that helps the body's defence system recognise and attack cancer.
Source: NCI, 2026
Implanted port
A small device placed under the skin and connected to a large vein. It avoids pricking the arm veins at each infusion.
Source: NCI, 2026
In situ
Cancer that has stayed inside the duct or lobule, without invading the tissue around it. This is stage 0.
Source: ACS, 2026
Incidence
The number of new cases of a disease over a period, for example one year.
Source: NCI, 2026
Invasive
Cancer that has gone through the wall of the duct or lobule and invaded the tissue around it.
Source: ACS, 2026
Ki-67
A marker that shows how fast cancer cells are dividing.
Source: NCI, 2026
Lobular carcinoma
Cancer that starts in the lobules, the small glands that make milk.
Source: ACS, 2026
Lumpectomy
An operation that removes only the tumour and a little healthy tissue around it, keeping the breast.
Source: NCI, 2026
Lymph node
A small bean-shaped organ that filters lymph. Those in the armpit are often examined in breast cancer.
Source: NCI, 2026
Lymphoedema
Swelling of the arm due to poor lymph circulation, sometimes after lymph nodes are removed or after radiotherapy.
Source: ACS, 2026
Malignant
Cancerous: able to invade and spread.
Source: NCI, 2026
Mammogram
An X-ray of the breasts using a low dose of radiation. It can show cancer before it can be felt.
Source: NCI, 2026
Mastectomy
An operation that removes the whole breast.
Source: NCI, 2026
Metastasis
Cancer that has spread far from where it started, for example to the bones, liver, lungs or brain.
Source: NCI, 2026
Mortality
The number of deaths caused by a disease over a period.
Source: NCI, 2026
Mortality-to-incidence ratio
The number of deaths divided by the number of new cases. The higher it is, the more deadly the disease relative to the number of cases.
Source: CA Cancer J Clin, 2026
MRI
An imaging test using a powerful magnet, with no X-rays. Useful in some cases, for example in women at very high risk.
Source: ACS, 2026
Neoadjuvant treatment
Treatment given before surgery to reduce the size of the tumour.
Source: NCI, 2026
Oncologist
A doctor who specialises in cancer.
Source: NCI, 2026
Pathology
Examination of a piece of tissue under the microscope. It is what confirms whether or not there is cancer.
Source: NCI, 2026
Radiotherapy
Treatment with high-energy rays that destroy cancer cells in a precise area.
Source: NCI, 2026
Recurrence
The cancer coming back after treatment.
Source: NCI, 2026
Remission
A decrease or disappearance of the signs of cancer after treatment.
Source: NCI, 2026
Screening
A test done in a person with no signs, to find cancer very early.
Source: NCI, 2026
Sentinel lymph node
The first lymph node the cancer could spread to. It is removed and analysed to know whether other nodes are affected.
Source: NCI, 2026
Stage
A number from 0 to IV that says how far the cancer has spread. The lower the stage, the better the chances of cure.
Source: ACS, 2026
Swollen lymph node
A swollen lymph node. Under the arm, it can be a sign to show the doctor.
Source: NCI, 2026
Targeted therapy
A medicine aimed at a precise target in cancer cells, for example the HER2 protein.
Source: NCI, 2026
TNM
A classification system: T for tumour size, N for lymph nodes, M for metastases.
Source: ACS, 2026
Triple-negative
Cancer with no oestrogen receptors, no progesterone receptors and no excess HER2. It is often more aggressive and more often affects young women.
Source: ACS, 2026
Ultrasound
A test using sound waves, with no radiation, that shows whether a lump is solid or filled with fluid.
Source: ACS, 2026
Information based on publications by the WHO, the International Agency for Research on Cancer (IARC), the French National Cancer Institute, the American Cancer Society, the National Cancer Institute, Cancer Research UK and published scientific studies.