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Glossary of Terms

Analytical Validity, Clinical Validity, Clinical Utility

Analytical validity describes how accurately and reliably the test detects and measures a biomarker of interest. Clinical validity provides some insight into how well the test relates to the clinical outcome of interest, e.g., response to therapy, survival, etc. Clinical utility describes whether the results of the test provide information that can contribute to and improve current optimal management of the patient’s disease.33


Biomarkers are defined characteristics in the body that are measured as indicators of health, disease, or a response to an exposure or intervention, including treatment. Biomarkers can help diagnose a disease, or predict future disease severity or outcomes, like measurements of blood pressure as an indicator of cardiovascular risk or measurements of blood sugar in diabetes. Biomarkers also are used to identify the best treatment for a patient, to monitor the safety of a therapy, or to find out if a treatment is having the desired effect on the body.5

Biomarker Testing

Biomarker testing is a way to look for genes, proteins, and other substances (called biomarkers or tumor markers) that can provide information about a cancer. Each person’s cancer has a unique pattern of biomarkers. Some biomarkers affect how certain cancer treatments work.34

Clinical Laboratory Improvement Amendments (CLIA)

The Clinical Laboratory Improvement Amendments of 1988 (CLIA) regulations include federal standards applicable to all US facilities or sites that test human specimens for health assessment or to diagnose, prevent, or treat disease.35

Companion Diagnostic

A companion diagnostic test provides information that is essential for the safe and effective use of a corresponding drug or biological product. The test helps a health care professional determine whether a particular therapeutic product’s benefits to patients will outweigh any potential serious side effects or risks. Companion diagnostics can identify patients who are most likely to benefit from a particular therapeutic product, identify patients likely to be at increased risk for serious side effects due to treatment with a particular therapeutic product, or monitor response to treatment with a particular therapeutic product for the purpose of adjusting treatment to achieve improved safety or effectiveness.36


DNA is the molecule that carries genetic information for the development and functioning of an organism. DNA is self-replicating material that is present in nearly all living organisms as the main constituent of chromosomes. It is the carrier of genetic information. The DNA from any two people is 99.9% identical. The differing 0.1% contains variations that influence individuals’ uniqueness.37


Genes are the basic unit of heredity passed from parent to child. Genes are made up of sequences of DNA and are arranged, one after another, at specific locations on chromosomes in the nucleus of cells. In humans, genes vary in size from a few hundred DNA bases to more than 2 million bases.38

Gene Mutations

A gene mutation is a change in one or more genes. Some mutations can lead to genetic disorders or illnesses.39

Genetic Testing for Inherited Risk

Genetic testing looks for specific inherited changes (variants) in a person’s genes. Genetic variants can have harmful, beneficial, neutral (no effect), or unknown or uncertain effects on the risk of developing diseases. Harmful variants in some genes are known to be associated with an increased risk of developing cancer. These inherited variants are thought to contribute to about 5-10% of all cancers.51


The genome is 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. The genome contains all the information needed for a person to develop and grow.52

Genome Sequencing

Genome sequencing is figuring out the order of DNA nucleotides, or bases, in a genome—the order of As, Cs, Gs, and Ts that make up an organism’s DNA. The human genome is made up of over 3 billion of these genetic letters.53


Immunotherapy is treatment that uses a person’s own immune system to fight cancer. Immunotherapy can boost or change how the immune system works so it can find and attack cancer cells.40

Lab Developed Test (LDT)

A laboratory developed test (LDT) is a type of diagnostic test that is designed, manufactured, and used within a single laboratory. LDTs can be used to measure or detect a wide variety of analytes (substances such as proteins, chemical compounds like glucose or cholesterol, or DNA), in a sample taken from a human body. Some LDTs are relatively simple tests that measure single analytes, such as a test that measures the level of sodium. Other LDTs are complex and may measure or detect one or more analytes. For example, some tests can detect many DNA variations from a single blood sample, which can be used to help diagnose a genetic disease.41

Liquid Biopsy

Liquid biopsy is a test done on a sample of blood to look for cancer cells from a tumor that are circulating in the blood or for pieces of DNA from tumor cells that are in the blood. A liquid biopsy may be used to help find cancer at an early stage.42

Molecular Profiling

Molecular profiling is a laboratory method that uses a sample of tissue, blood, or other body fluid to look for certain genes, proteins, or other molecules that may be a sign of a disease or condition, such as cancer.43

Molecular Subtype

The molecular subtype of a cancer is based on the genes the cancer cells express, which control how the cells behave.44

Next Generation Sequencing

Next-generation sequencing (NGS) is a massive parallel sequencing technology that offers ultra-high throughput, scalability, and speed. There are multiple different NGS platforms that use different sequencing technologies. All NGS platforms perform sequencing of millions of small fragments of DNA in parallel. Bioinformatics analyses are used to piece together these fragments by mapping the individual reads to the human reference genome. Each of the three billion bases in the human genome is sequenced multiple times, providing high depth to deliver accurate data and insight into unexpected DNA variation.45

Panel Test

A panel test is a laboratory procedure in which a series of tests is performed on one specimen.46


A pathologist is a medical healthcare provider who examines bodies and body tissues. They are also responsible for performing lab tests. A pathologist helps other healthcare providers determine diagnoses and is an important member of the treatment team.47

Precision Medicine

Precision medicine looks at the genetics, environment, and lifestyle of a person to select treatment that could work best for them.48

Prior Authorization

Prior authorization (PA) refers to a requirement by health plans for patients to obtain approval of a health care service or medication before the care is provided. It is supposed to contain costs, ensure that a treatment is medically necessary, and protect patient safety. PA requirements can delay treatment, restrict access to medications or specialists, and increase costs for patients and clinical practices.49

Single Analyte Test

A single analyte test is an assay designed for testing or measuring only a single analyte, which is a chemical substance in a fluid or other specimen from the body.50

Targeted Therapy

A targeted therapy is a type of treatment that uses drugs or other substances to identify and attack specific types of cancer cells with less harm to normal cells. Some targeted therapies block the action of certain enzymes, proteins, or other molecules involved in the growth and spread of cancer cells.54

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