The short answer
ER and PR status tell whether breast cancer cells have receptors for the hormones estrogen and progesterone. Positive results mean hormone therapy may help.
ER means estrogen receptor; PR means progesterone receptor.
These receptors are found on some breast cancer cells.
'Positive' means the cells have the receptors and may respond to hormone therapy.
'Negative' means the cells lack them, and tumors without hormone receptors do not respond to hormone therapy.
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What the letters mean
This page is for anyone with breast cancer whose pathology report lists ER and PR status. It explains what the results mean, how they guide treatment, and what they do not tell you.
ER stands for estrogen receptor. PR stands for progesterone receptor. Both are proteins found on some breast cancer cells. Receptors act like docking stations. When the hormones estrogen or progesterone attach to these stations, they can signal the cell to grow.
A pathologist (a doctor who studies tissue under a microscope) tests your breast cancer tissue for both receptors. The result tells your care team whether these hormones are likely fueling your cancer.
Reading positive and negative
A positive result means the cancer cells carry these receptors. The NCI breast cancer treatment summary for clinicians (PDQ) says any staining of 1% of cells or more is considered positive for ER, and the same for PR. A negative result means the cancer cells lack them. Your report may list a percentage. Ask your care team what your exact numbers mean for you.
Why it guides treatment
ER and PR status is one of the most useful parts of a breast cancer report. It points directly at whether hormone therapy is likely to help. Hormone therapy slows or stops the growth of some breast tumors by blocking the body's ability to produce hormones or by interfering with the effects of hormones on breast cancer cells. NCI says that, when taken for 5 years or more, it can greatly reduce the risk of new breast cancer, recurrence, and dying from breast cancer. Tumors that lack hormone receptors do not respond to hormone therapy.
About 80% of people diagnosed with breast cancer have hormone receptor-positive cancers, according to NCI.
The bigger biomarker panel
ER and PR are almost always tested together with a third marker, HER2. When all three come back negative, the cancer is called triple-negative. It is treated differently, and treatment may include surgery, chemotherapy, and more. Your pathology report should list ER, PR, and HER2 together. They are read as one panel, not separately.
What it does not tell you
Receptor status does not tell you the stage of your cancer. That means its size, and whether it has spread. It also does not guarantee how well hormone therapy will work for you. It identifies who is a reasonable candidate, not a guaranteed responder.
Is this urgent?
ER and PR testing is routine and expected. It is not an emergency finding on its own. What matters is making sure results are ready before treatment planning begins, since they shape which drugs are offered.
If your cancer returns
If your cancer comes back, ask your care team whether your receptor status will be checked again on the new tissue.
What to ask your team
- What were my exact ER and PR percentages, not just positive or negative?
- What does this mean for hormone therapy specifically?
- How do these results fit with my HER2 status?
Sources
Common questions
What are ER and PR?
They are receptors — docking points — on some breast cancer cells for the hormones estrogen (ER) and progesterone (PR). Their presence affects how the cancer may be treated.
What does ER-positive mean?
It means the cancer cells have estrogen receptors, so estrogen can encourage them to grow. These cancers often respond to hormone therapy that blocks or lowers estrogen.
Is ER-positive or ER-negative better?
ER-positive cancers can be treated with hormone therapy, which is an advantage. Outlook depends on many factors, so no single result defines it.
How is this related to HER2 and triple-negative?
ER, PR, and HER2 are tested together. When all three are negative, the cancer is called triple-negative, which is treated differently.
More words from this kind of report
Other guides in biomarker & genetic tests.
Your next step
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Written by: Cancer ExplainedSources last checked: 2026-07-14 what this meansLast updated: 2026-10-16Next 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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