Test guide
PDL1 (Immunotherapy) Tests
A PD-L1 test uses a sample of cancerous tumor tissue to measure how much of a protein called programmed-death ligand 1 (PD-L1) is found on the cancer cells. Normally, PD-L1 is found on certain healthy cells. It helps keep your immune system from attacking healthy tissue by acting as a kind of "brake" on your immune system cells (called T-cells). However, in some cancers, PD-L1 keeps your immune system from attacking cancerous cells.
What it is for
PD-L1 testing is mainly used to help your provider decide on treatment options for certain cancers. However, there are different types of PD-L1 tests. The test your provider orders will depend on: With the results from these tests, your provider can then not only decide whether immunotherapy will work, but how best to use immunotherapy. They may, for example, decide between: Source: MedlinePlus, National Library of Medicine. Medical test information is public domain. Source identity and definition checked automatically on 2026-10-18. No individual clinical interpretation or human reviewer is asserted.
Limitations
Reference intervals and interpretation depend on the laboratory, specimen, method and clinical context. This source definition is educational information; it does not establish a diagnosis, product approval or suitability for an individual.
Also known as
- programmed death-ligand 1, PDLI, PDL-1 by immunohistochemistry (IHC)
Reviewed products
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