Understanding the Genomics and Genetics of Cancer

Adjuvant therapy — Additional cancer treatment given after primary treatment to lower the risk the cancer will come back.

Benign — Not disease-causing.

Cytogenetics — The study of chromosomes to look for changes, including broken, missing, rearranged or extra chromosomes.

DNA — Deoxyribonucleic acid. The molecules inside cells that carry genetic information that is passed from one generation to the next.

DNA sequencing — A laboratory process used to learn the exact sequence (order) of the four building blocks, or bases, that make up DNA to find DNA mutations (changes) that may cause diseases, such as cancer.

First-line therapy — The first treatment used.

Fluorescence in situ hybridization (FISH) — FISH can be used to identify where a specific gene is located on a chromosome, how many copies of the gene are present and any chromosome abnormalities.

Genome — The complete set of DNA (genetic material) in an organism. In people, almost every cell in the body contains a complete copy of the genome, which contains all of the information needed for a person to develop and grow.

Genomic sequencing — This is used to determine the entire genetic makeup of a specific organism or cell type. This can be used to find changes in areas of the genome and to diagnose and treat cancer.

Histologic grade — This is a description of a tumor based on how abnormal the cancer cells and tissue look under a microscope. It also helps determine how quickly the cancer cells are likely to grow and spread.

Liquid biopsy — A test done on a sample of blood to look for cancer cells or pieces of DNA from a tumor that are circulating in the blood. A liquid biopsy may also be used to help plan treatment, to find out how well treatment is working or to determine whether cancer has come back. Being able to take multiple samples of blood over time may also help doctors understand what kind of molecular changes are taking place in a tumor. It is convenient, can be repeated frequently and does not require a surgical procedure.

Local treatment — Directed to a specific organ or limited area of the body, it includes surgery, radiation therapy and topical therapy (a lotion or cream that is applied to the skin).

Molecular testing — Checks for certain genes, proteins or other molecules in a sample of tissue, blood or other body fluid. Molecular tests also check for certain changes in a gene or chromosome that may affect the chance of developing cancer. It is done to help diagnose some types of cancer, plan treatment, fin our how well treatment is working or make a prognosis (prediction of outcome).

Mutations — Also referred to as changes or variants, mutations are the difference between an individual's genetic code when compared to the human reference sequence, which is representative of the sequence (order) of genes in one idealized individual. Some are benign, pathogenic or of unknown significance. 

Neoadjuvant therapy — Treatment given as a first step to shrink a tumor before the main treatment (usually surgery) is given.

Next-generation sequencing (NGS) — Tests that detect differences in a patient's genome from a reference genome, which is a representative example of the set of genes in one idealized individual. It identifies sections of DNA that represent changes, including insertions or deletions, in a specific DNA sequence.

Oncogene — A mutated form of a gene involved in normal cell growth. Oncogenes may cause the growth of cancer cells. Mutation sin genes that become oncogenes can be inherited or caused by exposure to cancer-causing substances.

Pathogenic — Disease-causing.

Pathological stage — The stage of cancer based on how different from normal the cells in cancer tissue samples look when examined under a microscope.

Second-line therapy — Given when the first-line therapy does not work or is no longer effective.

Standard of care — The best treatment known for the type and stage of a particular cancer.

Tumor microenvironment — The cells, molecules and structures that surround and support a tumor. Abnormal cells, such as cancer cells, can change their microenvironment, which can affect how cancer cells grow and spread.