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PD-L1 testing: what it means for you

Waiting on test results can feel like one more hard thing, for you and the people who love you. Here's what the PD-L1 test looks for and how it can help your care team pick the treatment most likely to work for you.

ℹ️ General information to help you and your loved ones talk with your care team, not medical advice. Read our disclaimer.

Matters most in: Lung cancer, Breast cancer

Why it matters

PD-L1 helps cancer hide from the immune system. A higher score can mean immunotherapy is more likely to help, and in some cancers it decides whether immunotherapy alone or with chemo is an option. A low score doesn't always rule immunotherapy out.

Treatments it can point to

• Immunotherapy (PD-1/PD-L1 blockers) such as Keytruda or Opdivo (Keytruda (pembrolizumab), Opdivo (nivolumab))
• Lung: chemo plus immunotherapy such as carboplatin + pemetrexed + Keytruda (Alimta (pemetrexed), Carboplatin)

Only your care team can say which treatment fits you. Drug approvals depend on cancer type, stage and prior treatment.

Tissue vs. blood testing

Tissue only.

Most tests use a piece of tumor tissue from a biopsy or surgery. Some can also use a blood sample (a 'liquid biopsy') that looks for tumor DNA floating in the blood. Blood tests are easier and faster, but they can miss a change that a tissue test would find, so a negative blood test is often followed by a tissue test.

❓ Questions you and your loved ones can ask

• What is my PD-L1 score, and what does it mean for my options?
• When will my results be back, and will treatment wait for them?
• Will my insurance cover this test?

Written by the Cancer Side Effects Guide team from FDA labels and leading cancer centers. Not medical advice. · Last updated: October 15, 2026 · How we write