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Glossary

The page lists all glossary terms and their definitions as they appear across the site.

 

 

absolute risk

The chance of developing a disease (such as cancer) during a given time. For example, the absolute risk of a woman developing breast cancer by the age of 85 years is 1 in 8.

benign

Not cancerous. Benign cells are not able to spread like cancer cells.

biopsy

Removal of a small amount of tissue from the body for examination under a microscope, to help diagnose a disease.

body mass index (BMI)

A measure of body fatness. BMI is calculated by dividing your weight (in kilograms) by the square of your height (in metres squared). For example, a person who weighs 65 kg and is 170 cm tall has a BMI of 22.5 (= 65/1.72).

BRCA1 gene

Breast Cancer susceptibility 1 gene. Women who have a mutation in the BRCA1 gene have an increased risk of breast cancer. The BRCA1 gene produces a protein that helps to repair DNA when it is damaged. When the gene is mutated, the protein stops working.

BRCA2 gene

Breast Cancer susceptibility 2 gene. Women who have a mutation in the BRCA2 gene have an increased risk of breast cancer. The BRCA2 gene produces a protein that helps to repair DNA when it is damaged. When the gene is mutated, the protein stops working.

breast cancer

Cancer of the breast. Breast cancer is most common in women, but also affects a small number of men. A term for diseases in which abnormal cells divide without control. Cancer cells can invade nearby tissues, and can spread through the bloodstream and lymphatic system to other parts of the body.

cancer

A term for diseases in which abnormal cells divide without control. Cancer cells can invade nearby tissues, and can spread through the bloodstream and lymphatic system to other parts of the body.

carcinogen

A substance known to cause and/or promote cancer. Carcinogens can be created by humans (eg cigarette smoke) or can be present naturally in the environment (eg ultraviolet radiation from the sun).

carrier

A person who has a single copy of a particular variation of a gene in their genetic makeup (rather than 2 copies of that variation). For many genes, this means that the gene does not cause any symptoms. However, the carrier of the gene can pass it on to their children.

case–control study

A type of study design to find out whether a particular factor is associated with the risk of cancer. A group of people with cancer (the ‘cases’) is compared with a matched group without cancer (the ‘controls’) to look at the differences between the 2 groups (eg level of alcohol consumption).

cells

The building blocks of the body. A human body is made of millions of cells, which are adapted for different functions. Cells can reproduce themselves exactly, unless they are abnormal or damaged, as are cancer cells.

chemotherapy

The use of medicines that kill or slow cell growth to treat cancer.

chromosome

A threadlike structure found in the nucleus of all body cells (except red blood cells) made up of genes.

convincing

There is compelling and consistent evidence that the factor increases or decreases the risk of breast cancer.

cohort study

A type of study design to find out whether a particular factor is associated with the risk of cancer. A group (cohort) of people with a particular risk factor for cancer is followed over a period and compared with a matched group without that risk factor.

confidence interval

A range of values surrounding the true value. Confidence intervals are used in statistical studies that look at a sample of people to draw conclusions about the whole population. A 95% confidence interval means that we can be 95% confident that the true value falls within this range.

confounder, confounding factor

In studies of risk factors that are associated with cancer, a confounder is a different factor that is also associated with risk of cancer. Confounders can lead to the wrong conclusions about the cause of cancer if they are not taken into account. For example, if the risk factor being studied is consumption of sugar, women who eat a lot of sugar might also have more body fat than average – body fat is a confounder in this case.

diagnosis

The identification and naming of a person’s disease.

DNA

Deoxyribonucleic acid, the genetic material found in human cells that makes up the genes.

dose–response relationship

A situation where an increasing dose of something, or exposure to something, has a greater effect. For example, there is a dose–response relationship between alcohol consumption and the risk of breast cancer. The more a woman drinks, the higher her risk of breast cancer.

ductal breast cancer

Cancer that develops in the milk ducts of the breast.

epidemiology

The study of the patterns and causes of health and disease in populations, and the application of this study to improve health.

epithelium

The cells that make up the internal and external surfaces of the body (eg skin, inside of lungs, surface of ovaries).

evidence

The observations and experimental results that support a hypothesis.

evidence of no association

There is consistent evidence from good quality studies to show that this factor neither increases nor decreases the risk of breast cancer.

familial

Indicates that a condition can be inherited through the generations of a family through one or more genes.

family history

Occurrence of cancer within the same family. This might be because of inheritance of genes. However, members of a family often also have similar lifestyles (eg diet, exercise), meaning that they can share lifestyle risk factors for breast cancer.

first-degree relative

Parents, brothers, sisters and children.

genetic disease

A disease that is caused by defects in genes and is passed from one generation to the next.

gene

The elements of a cell that carry instructions on how the cell should grow and function. Each person has a set of many thousands of genes inherited from both parents. This set is found in every cell of the body.

germline

Cells in the body that will become sperm cells or egg cells. The genetic material in these cells can be passed on to the next generation.

HER2 breast cancer

A type of breast cancer in which a protein on the surface of breast cells (human epidermal growth factor receptor 2) is made in larger amounts than usual. This can make the cells grow in an uncontrolled way and lead to breast cancer.

heterozygous

For a particular gene, heterozygous means that each cell in the body contains two different versions of the gene – one inherited from the mother and one from the father. This is usually one copy of the normal gene and one copy of a mutated form of the gene.

homozygous

For a particular gene, homozygous means that each cell in the body contains two identical versions of the gene – inherited from the mother and the father.

hormone

A substance made in the body that affects how your body works. Some hormones control growth; others control reproduction. Hormones travel around the body in the bloodstream.

hormone replacement therapy

Therapy that supplies the body with hormones that it is no longer able to produce; it is used to relieve menopausal symptoms.

IARC

International Agency for Research on Cancer – the cancer agency of the World Health Organization.

inconclusive

The evidence is too limited to determine the likelihood of an association with increased or decreased risk of breast cancer.

lifestyle factors

Risk factors relating to a person’s lifestyle – for example, diet, alcohol consumption, smoking, weight gain and weight loss, obesity, and level of physical activity.

lifetime risk

The chance of developing cancer during your lifetime. For example, a woman with no known risk factors for breast cancer has a lifetime risk of developing breast cancer of about 12%.

lobular breast cancer

Cancer that develops in the milk-producing glands of the breast.

luminal breast cancer

A type of breast cancer, based on particular proteins that occur on the surface of the breast cells.

mammogram

A process that takes a picture of the breast using low-energy X-rays to detect breast cancer.

meta-analysis

A type of study that combines the results from multiple individual studies. This can give more reliable results than a single study, and can also highlight interesting differences between the individual studies.

mutation

A change in the DNA sequence of a gene. Mutations can occur in a person’s DNA during their lifetime, or can be inherited from their parents.

odds

The likelihood that something will occur – for example, that a woman will develop breast cancer.

odds ratio

The likelihood that breast cancer will develop in the presence of a particular risk factor compared with the likelihood in the absence of that risk factor. For example, an odds ratio of 2 for a risk factor means that women with that risk factor have twice the chance of developing breast cancer as other women.

oestrogen

The main female sex hormone, produced mostly by the ovaries. Oestrogen regulates the menstrual cycle and prepares the breasts for milk production.

estrogen-receptor-positive (ER+) breast cancer

A type of breast cancer in which the breast cancer cells have proteins on their surface (oestrogen receptors) that allow them to use the hormone oestrogen to grow. About 80% of all breast cancers are ER+.

oestrogen-receptor-negative (ER–) breast cancer

A type of breast cancer that is not oestrogen-receptor-positive.

ovarian cancer

Occurs when abnormal cells in the ovary, fallopian tube or peritoneum grow in an uncontrolled way.

pooled analysis

A type of study that combines the results from multiple individual studies. This can give more reliable results than a single study. It can only be used if the individual studies used the same design and similar populations.

primary cancer

The original cancer. Cells from the primary cancer may break away and be carried to other parts of the body, where secondary cancers form.

probable

The factor is likely to be associated with increased or decreased risk of breast cancer, but the evidence is not as strong as for convincing.

progesterone

A sex hormone, produced by the ovaries, that plays an important role in the menstrual cycle and in maintaining the early stage of pregnancy.

progesterone-receptor-positive (PR+) breast cancer

A type of breast cancer in which the breast cancer cells have proteins on their surface (progesterone receptors) that allow them to use the hormone progesterone to grow.

radiotherapy

The use of radiation, usually X-rays or gamma-rays, to kill tumour cells, or injure them so that they cannot grow or multiply.

recall bias

In studies of cancer risk, recall bias occurs when people in the study cannot completely or accurately remember events or experiences in the past. This can lead to misleading results.

relative risk

A measure of risk that compares the absolute risk of developing a disease (such as cancer) in a group of people who have a particular risk factor with the absolute risk in a group of people who do not have that risk factor. For example, a certain gene mutation might double the risk of breast cancer – the relative risk is 2 for that risk factor.

risk

A measure of how likely a person is to develop a disease or a side effect.

risk factor

A substance or condition that increases a person’s chances of getting a particular type of cancer.

sarcoma

A malignant tumour (a cancer) that starts in connective tissue.

second-degree relative

Aunts, uncles, grandparents, grandchildren, nieces, nephews and half-siblings.

single nucleotide polymorphism

A change in the genetic material (DNA) at a single location in the DNA.

suggestive

The evidence is indicative of an association between the factor and increased or decreased risk of breast cancer, but there is not sufficiently strong evidence to be more certain.

systematic review

A type of review of the literature that uses systematic methods to critically assess the relevant research on a topic. The aim is to thoroughly summarise the current evidence on that topic.

tissue

A collection of cells that make up each piece (or organ) of the body.

triple-negative breast cancer

A type of breast cancer in which the breast cancer cells do not have oestrogen receptors or progesterone receptors, and do not produce too much of the HER2 protein. Many breast cancers associated with the BRCA1 gene are triple negative.

tumour

An abnormal growth of tissue. It may be localised (benign) or invade adjacent tissues (malignant) or distant tissues (metastatic).

tumour suppressor genes/proteins

Genes (and proteins) that occur in our bodies that stop cells growing in an uncontrolled way and developing into cancer. They often work by repairing mistakes that occur in our DNA.

World Cancer Research Fund International

A not-for profit organisation that unites a network of cancer prevention charities, including the American Institute for Cancer Research in the United States.