The short answer
Immunohistochemistry (IHC) is a lab test that uses special stains to find particular proteins in tissue. It helps identify a cancer's type and features that guide treatment.
IHC uses antibodies and stains to detect specific proteins in tissue.
It helps confirm the type and origin of a cancer.
It can reveal markers like hormone receptors or HER2.
Results help match a cancer to the right treatment.
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This page is for people whose pathology report lists immunohistochemistry (IHC) results. It explains what the test does, what it can and cannot tell you, and how long results take.
What IHC is
Immunohistochemistry, usually shortened to IHC, is a laboratory test. It uses special stains to find specific proteins inside a tissue sample. The test relies on antibodies, which are proteins that latch onto one particular target and nothing else. Each antibody is tagged with a dye. When the antibody finds its target protein in the tissue, the dye lights it up under the microscope.
IHC is performed on tissue that has already been collected, usually from a biopsy or surgery. A biopsy is how the tissue is obtained. IHC is one of the tests a pathologist runs on that tissue afterward, alongside looking at the cells' basic shape and pattern.
What questions IHC answers
IHC helps answer several different questions, depending on which markers are tested:
- It can help confirm what kind of cancer is present, especially when the cells' basic appearance alone is not enough to tell.
- It can offer clues about where a cancer started. This matters when cancer is found in another site but its original source is not obvious.
IHC is also used to look for biomarkers, such as hormone receptors or HER2 in breast cancer. Ask your care team which markers were tested on your sample and what each result means for you.
How results are reported
IHC results are usually reported as positive, negative, or with a percentage or score describing how much staining was seen and how strong it was. The exact scoring method depends on which marker is being tested. Different markers can use different scoring methods. Your pathology report may list several IHC markers together, each with its own result and its own meaning for treatment.
What it changes about your care
Some treatments are matched to biomarker results. Ask your care team how your IHC results affect your options.
What it does not tell you
IHC is not a stand-alone diagnosis. It is interpreted together with the tissue's basic appearance, its grade, its stage, and sometimes other molecular tests. A single IHC marker rarely decides treatment by itself. It is one input your care team weighs alongside everything else in your report.
IHC also does not test DNA directly the way genetic sequencing does. It detects proteins, which are downstream of the genes that make them. Some questions about genetic mutations require a different kind of test entirely.
Timing
IHC is a planned lab test on tissue that has already been collected. Ask your care team when your results will be ready, since some treatment decisions wait on them. If you have not heard back by then, call and ask.
What to ask your team
- Which IHC markers were tested on my sample, and what were the results?
- How do these results change my treatment options?
- Is there a marker that was not tested that might be worth adding?
- How does this fit with any other biomarker or genetic testing I've had?
Sources
- National Cancer Institute — Diagnosis and Staging, which says a pathologist runs other tests on the cells in a sample
Common questions
What is immunohistochemistry?
It is a laboratory test that applies antibodies, tagged with a visible stain, to a tissue sample. The stain lights up specific proteins, helping identify what kind of cells are present.
Why is it done?
IHC helps confirm the type of cancer, suggest where it started, and detect markers — such as hormone receptors or HER2 — that guide treatment decisions.
Is it the same as a biopsy?
No. A biopsy is how the tissue is collected. IHC is one of the tests a pathologist may run on that tissue in the lab.
How reliable is it?
Results are interpreted by a pathologist alongside the tissue's appearance and other tests.
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Written by: Cancer ExplainedSources last checked: 2026-10-02 what this meansLast updated: 2026-08-10Next planned review: 2027-07-14
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Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes, and this is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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