Gene and marker tests
PD-L1 (TPS, CPS)
Also written as PD-L1 positive, PD-L1 TPS, PD-L1 CPS, PDL1 expression, PD-L1 22C3, Tumour proportion score, Combined positive score
What it means
PD-L1 is a protein that acts like a brake on the immune system. Some cancer cells have more PD-L1 than normal. Immune checkpoint inhibitors are drugs that block PD-L1 and release this brake. The CPS score counts PD-L1 staining cells against all viable tumour cells.
Why it matters
The PD-L1 score is one result your oncologist may use when thinking about immunotherapy. It does not decide treatment alone.
Ask your oncologist
"What is my PD-L1 score and how does it affect whether immunotherapy is an option?"
From NCI Dictionary of Cancer Terms: PD-L1 and NCBI MedGen: PD-L1 Combined Positive Score (definition from NCI). Not medical advice: your oncologist decides.