Identifying and evaluating cancer biomarkers requires specific tests and interpretation of results. The terms in this section may be applicable in ordering or understanding pathology tests and results.
Many of the terms that describe biomarker testing are used interchangeably but may have different meanings. Biomarker testing should be considered an umbrella term that includes the other terms listed below, which also have overlapping applications.
Tests that look for changes among various biological markers.
The removal of cells or tissues for pathology testing.1
Paraffin-Embedded Tissue Block
A method of preparing biological samples for processing, staining, sectioning, and examination by a pathologist.6
Also called: Cell block
cfDNA (cell-free DNA)
DNA from a biologic fluid that is found outside the confines of a cell, that can be used for NGS testing. Obtaining cfDNA requires special procedures and typically produces low yields, yet varies by patient, cancer type, and cancer stage.7
ctDNA (circulating tumor DNA)
DNA from a biologic fluid that originated from a tumor cell and is found outside the confines of the cell.7
Combined Positive Score (CPS)
The ratio of all PD-L1-expressing cells (tumor cells, lymphocytes, macrophages) to the number of all tumor cells in a sample. CPS is often used to identify patients likely to respond to anti-PD-1/PD-L1 therapy. 8
A medical device, or in vitro diagnostic (IVD), that provides information to determine if a specific therapy is likely efficacious and of benefit to the patient. 9
Comprehensive Genomic Profiling (CGP)
A tumor testing method that uses multiple samples and NGS technology to detect biomarkers which drive cancer growth or may predict response to therapies. 10
The study of chromosomes, including testing samples to look for chromosomal changes such as broken, missing, or extra chromosomes.1
The study of the structure, function, and chemistry of cells using a microscope.1
Discrepancy between any two or more test results for a single sample.
An ambiguous pathology result that requires additional testing. This may be due to technical or biologic causes.
Flow Cytometry (flow)
A method of measuring certain characteristics of cells in a sample, such as unusual markers on the surface of cells or the number of healthy and cancerous cells.1
FISH (fluorescence in situ hybridization)
A laboratory technique which uses fluorescent dye to look at targeted chromosomes or genes in cells or tissues, specifically to assess genetic mutations.1
The study of the anatomy of cells and tissues using a microscope.1
A lab test that uses antibodies to identify and examine specific antigens in a tissue sample under a microscope, including specific cancer biomarkers.1
A process that uses blood, bone marrow, or other tissue to test for the presence or absence of cell antigens. This type of testing is often used to detect certain markers associated with types of leukemia and lymphoma, many of which are identified by a CD (cluster of differentiation or cluster designation).1, 14
The ability to draw similar conclusions through replicating or reanalyzing a study or test.11
A test done on a sample of blood to identify circulating cancer cells or molecules (such as DNA) from cancer cells. Liquid biopsies can help with early diagnosis, planning and tracking treatment, and tracking molecular changes.1
The ability to use the same experimental procedures, data, and tools and achieve the same results.11
The scientific study of the form and structure of cells or organisms.1
NGS (next-generation sequencing)
A time- and cost-efficient form of molecular testing which allows for multiple DNA sequences to be processed in parallel.1
Also called: Massively parallel sequencing
The ability to corroborate the results from another study using the same methods.11
Tumor Mutational Burden (TMB)
The total number of genetic changes found in the DNA of cancer cells. Knowing the TMB can help inform treatment decisions, particularly when the TMB is high.1
Tumor Proportion Score (TPS)
The percentage of viable tumor cells showing partial or complete membrane staining, relative to all viable tumor cells present in a sample. TPS is often used to identify patients likely to respond to anti-PD-1/PD-L1 therapy.8
Testing results that were abnormal or not anticipated, typically of significance.12