Info
PD-L1
A protein that can protect tumor cells from immune attack. The PD-L1 value helps doctors decide whether immunotherapy may be effective.
What it means
A protein produced by some tumor cells that can block the immune system's attack. Immunotherapy with checkpoint inhibitors targets exactly this brake. PD-L1 testing helps select eligible patients.
In short
A protein that can protect tumor cells from immune attack. The PD-L1 value helps doctors decide whether immunotherapy may be effective.
Where you will see it
Mentioned in the immunohistochemistry report. Expressed as a TPS or CPS score, in percentages.
What it does not tell you on its own
PD-L1 does not on its own decide whether immunotherapy will work — patients with low PD-L1 can also respond, and those with high PD-L1 may not respond.
Questions for your doctor
- Was PD-L1 tested in my case?
- What is my score?
- Am I eligible for immunotherapy based on this result?
- What other criteria matter for eligibility?
Related terms
The terms below often appear alongside this one. Each definition is right here, so you do not have to look elsewhere.
- Immunohistochemistry
- A laboratory technique that uses antibodies to detect specific proteins in tumor cells. It helps establish the exact type of cancer and choose the right treatment, especially in breast, colon and lung cancers.
- Immunotherapy
- A treatment that helps the patient's immune system recognize and attack cancer cells. It works by releasing the brakes on the immune system or by directly stimulating lymphocytes. It can cause autoimmune side effects.
- HER2
- A protein that can be present in large amounts on the surface of some cancer cells. HER2 positive means that the tumor may respond to specific biological treatments that target this protein.
Other terms in “Diagnosis”
Glossary definitions are written for patients by the OncoDots team and go through internal medical review. They explain terms; they do not establish a diagnosis and do not recommend a treatment.