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Glossary of terms

Scientific writing can be full of jargon and technical terms that can make it hard for a lay audience to understand. To address this, our patient advocates, Fran Visco and Helen Matthews have written this glossary to explain some of the technical terms frequently used on the SpecifiCancer website.



The presence of an abnormal number of chromosomes within a cell, for example, cells that have missing or extra chromosomes. This is common occurrence in cancer cells.



A type of cell death used by the body to get rid of abnormal or unneeded cells. Apoptosis may be blocked in cancer cells. 


The BRAF gene makes a protein that controls cell growth. A specific mutation in BRAF is often found in certain types of cancer, including melanoma and colorectal cancer.


Cell division cycle

The series of events by which a cell makes a copy of its DNA and other contents and then divides in two. The cell division cycle is often mis-regulated in cancer cells allowing them to continuously divide. 



The material that makes up chromosomes, a highly organised structure containing DNA and associated proteins. 



The molecules inside cells that carry genetic information and pass it from one generation to the next. Also called deoxyribonucleic acid.


DNA damage 

A change in the structure of DNA that could cause harm to a cell by changing its genetic information. Cells operate complex surveillance mechanisms to check for DNA damage and repair any damage found. These DNA damage response mechanisms are often altered in cancer cells. 


Driver mutation

A genetic alteration that gives a cancer cell a selective advantage over other cells, for example by promoting its division or survival. 



The mechanism that cells use to turn genes on or off. While all cells in the human body carry the same genome, cells in different tissues can carry out specialised functions by activating or deactivating subsets of genes.


Epithelial cancers

Cancers that develop in epithelial tissues, the sheets of tightly connected cells that cover body surfaces and line body cavities. Examples of epithelial tissues include the skin and intestine. 


EZH2 is a gene that becomes ‘turned on’ in many different cancer types, including breast and prostate cancer. The EZH2 gene codes for a protein that is part of the Polycomb repressive complex 2 (PRC2) that can modify DNA inside a cell to turn genes on or off (epigenetics). This can help cancer cells to survive and grow. 


Gain-of-function/loss-of function mutations

A gain-of-function mutation is a mutation that confers new or enhanced activity on a protein. For example, most oncogenes would be considered gain-of-function or activating mutations. A loss-of-function mutation decreases or abolishes the activity of a protein. Mutations in tumour suppressor genes would normally be classed as ‘loss of function’.



The unit of heredity passed from parent to offspring. Genes are pieces of DNA, and most genes contain the information for making a specific protein. For most genes, you have two copies of each gene that you inherited from your mother and your father. 



All of the genetic material (DNA) found within a cell.



The study of genes and genomes. The genome within an individual cancer cell can be read using ‘DNA sequencing’ to find out which mutations are present.


Genome-wide screening

A technique to assess the function of every gene within a cell. Each gene can be systematically ‘knocked down’ to remove its protein product and the effect on the cell can be assessed. This can be used to determine which genes are important for a cancer cells growth and survival.


Germline mutation

A genetic mutation that is inherited. An example would be the BRCA mutations in breast and ovarian cancer.



Organisms or cells that have the same genes. An example would be identical twins.  



A mutated form of a gene that normally controls cell growth, which has the ability to transform a normal cell into a cancer cell. Examples of oncogenes include KRAS and BRAF.



The process by which normal healthy cells become transformed into cancer cells and form a tumour.



A protein that is encoded by an oncogene that promotes the growth and survival of cancer cells.



An artificially grown 3D mass of cells that resembles a miniature organ and can be used in the lab to study human organs or tissues.


Orthotypic cancer model

An experimental approach where patient-derived cancer cells are implanted in the relevant tissue or organ in an animal (normally a mouse). This allows scientists to study how cancer cells behave in a disease-relevant natural environment.



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


Permissive/non-permissive tissues

Many cancer-causing genetic mutations will only induce tumours when the mutations occur in certain tissues. These are termed permissive tissues for this mutation (for example breast or ovarian tissues for BRCA mutations). Non-permissive tissues will never develop tumours even if cells develop this particular mutation.



An increase in the number of cells that occurs when cells divide.



The entire set of proteins that can be expressed within a cell or organism.



A field of biological research that studies the genome (genetic code) and proteome (entire set of proteins) within a cell or organism.



A family of genes that control cell growth. Mutations in one of the Ras genes, KRAS, is frequently found in certain types of cancer including colorectal cancer, pancreatic cancer and lung cancer.



One of two types of nucleic acid made by cells. RNA contains information that has been copied from DNA (the other type of nucleic acid). Cells make several different forms of RNA, and each form has a specific job in the cell. Many forms of RNA have functions related to making proteins. RNA can be made in the laboratory and used in research studies. Also called ribonucleic acid.


Signaling pathway

A chain of chemical reactions that occurs within a cell. The function of signalling pathways in some cases is to transmit information from outside (for example from the environment or other cells) into a cell to control its function (for example by inducing cell division or death). In other cases, the signalling may initiate from an event inside the cell such as an activated oncogene like KRAS.


Somatic mutation

A permanent alteration to the DNA sequence of a gene that occurs in an individual cell during a person’s lifetime. Somatic mutations can occur in any cell in the body except the germ cells (sperm and egg) and therefore are not passed on to children. Many cancers are caused by somatic mutations.


Stem cell

A cell that has the ability to develop into many different specialised cell types in the human body. Stem cells divide to supply new cells within tissues and replace damaged cells. 


Therapeutic vulnerability

A weakness that is specific to cancer cells that can be targeted by a drug as cancer therapy to kill cancer cells rather than healthy cells.


Tissue specificity

How mutations (mistakes) in certain genes frequently cause cancer in specific tissues or organs but almost never in others. For example, mutations in BRCA1 and BRCA2 are often associated with breast or ovarian cancer, but not with other cancer types.


Tissue agnostic therapy

A type of cancer drug that treats cancers based on the genetic mutations they display rather than the part of the body they appear. 


Tumour suppressor gene 

A normal gene that protects against the development of cancer, for example by slowing down cell growth, repairing DNA damage or telling damaged cells to die. Mutations that stop tumour suppressor genes working are common in cancer cells. Examples of tumour suppressor genes include APC, TP53 and BRCA1.


Wildtype gene

The normal, unmutated form of a gene (the opposite of a mutated form such as a tumour suppressor or oncogene).

Wnt signaling

A specific protein network that transmits signals from the Wnt protein that is secreted by other cells into a cell to promote cell growth, division and migration. Mutations in genes that code for various Wnt signaling proteins are found in many types cancers, most notably the APC gene, which is frequently altered in colorectal cancer.

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