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.
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. If you have one of these kinds of cancers and high levels of PD-L1, your provider can treat your cancer with immunotherapy (a treatment option that helps your immune system fight cancer). In cancers with high PD-L1 levels, health care providers use a type of immunotherapy called "immune checkpoint inhibitors." These medicines stop PD-L1 from binding to your T-cells. In other words, they "release the brakes," allowing your immune system to target and kill cancer cells. Other names: programmed death-ligand 1, PDLI, PDL-1 by immunohistochemistry (IHC)
Why is this test ordered? You may need a PD-L1 test if you've been diagnosed with certain types of cancer that commonly cause high PD-L1 levels. These cancers include: Non-small cell lung cancer Melanoma Hodgkin lymphoma Bladder cancer Kidney cancer Breast cancer Head and neck cancer (squamous cell carcinoma) Cancer of the esophagus (squamous cell carcinoma) Stomach cancer (adenocarcinoma) Cervical cancer Your provider may also order a PD-L1 test to monitor your treatment progress.
Clinical Interpretation
Your test results will show whether you have enough PD-L1 protein in your tumor for you to benefit from a specific immunotherapy medicine. Some immunotherapy medicines will not be helpful if a small percentage of your cancer cells have PD-L1. If your test results show that: Your tumor cells have enough PD-L1 for you to use immunotherapy medicine, you may be able to start that medicine. Common examples include pembrolizumab, nivolumab, and atezolizumab. This may be called a "positive" test result. Your tumor cells don't have enough PD-L1, then immunotherapy likely won't help you. This may be called a "negative" test result. Your provider will consider other types of cancer treatment that will be more effective. Your test results may also have different scoring systems and values. For example, you may see: Combined Positive Score (CPS), which measures PD-L1 on both tumor cells and T-cells. Tumor Propositional Score (TPS), which measures the percentage of tumor cells that have high amounts of PD-L1. These scoring systems and values can vary depending on what type of PD-L1 test your provider used. Because of these differences, you should talk to your provider about what your results mean. Your provider may also use other tests to help decide on the best treatment for you. Learn more about laboratory tests, reference ranges, and understanding results .
Clinical Protocol & Patient Advice
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Preparations for your test depend on how your tissue sample will be taken. You may need to stop taking certain medicines, such as blood thinners like aspirin, before this test. So, tell your provider about all the medicines and supplements you take. Don't stop or start taking anything unless your provider tells you to. Before you get any procedure, you should tell your provider about any recent surgeries or known allergies. You should also tell them if you're pregnant. If you're having general anesthesia, you will probably need to fast (not eat or drink) for several hours before surgery. If you have general anesthesia or medicine to relax, you may be groggy after the procedure, so plan to have someone take you home. Ask your provider how to prepare for your test.
Usage Guidance
- Reference ranges vary by laboratory. Always discuss your specific results with a qualified healthcare professional.
Source: MedlinePlus, National Library of Medicine. View the original.