The short answer
A margin is the rim of normal tissue around a removed tumor. Clear means no cancer at the edge, positive means cancer cells are at the edge, close means it comes near but does not touch.
The pathologist looks at the edge of the removed tissue. Margin terms all refer to that edge.
A clear or negative margin means no cancer cells were seen at the edge. A positive or involved margin means cancer cells are at the edge.
A close margin means cancer comes near the edge without touching it. The NCI fact sheet does not define it, so ask your team what close means on your report.
A positive margin is a finding to talk through with your care team. What happens next depends on your cancer and your plan.
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This page is for anyone whose pathology report describes surgical margins as clear, close or positive. It explains what each word means and what may happen next.
What a Margin Actually Is
When a surgeon removes a tumor, they take a rim of surrounding normal-looking tissue with it. That rim is the margin. A review hosted by NIH describes the pathologist marking the edge of the specimen with ink. Everything the report says about margins is a statement about that edge.
The question the pathologist is answering is narrow and specific: are there cancer cells at the edge?
The Three Words You Will See
Clear, also written as negative, clean or uninvolved, means no cancer cells were seen at the edge. The National Cancer Institute describes this as no cancer cells at the edge of the tissue, suggesting all of the cancer was removed.
Positive, also written as involved, means cancer cells are at the edge. The National Cancer Institute says this suggests some of the cancer has not been removed.
Close means cancer comes near the edge without touching it. This is the vaguest of the three. The NCI fact sheet does not define it. Ask your team what "close" means on your report.
The Part That Causes Most Alarm
A positive margin is a finding to talk through with your team. It does not mean you did something wrong.
What happens next depends on the type of cancer, which margin is involved, and the rest of your plan. Your care team decides this with you. Questions worth asking:
- Which margin is positive or close?
- Is more surgery, radiation or other treatment an option for me?
- What would each choice mean for my recovery?
Where the Thresholds Actually Come From
Margin standards differ by cancer type. If someone quotes you a number, it is fair to ask which cancer it comes from.
For invasive breast cancer treated with lumpectomy plus radiation, a review hosted by NIH says the consensus guideline uses "no tumor on ink" as the margin standard. The same review says wider margins did not lower the chance of recurrence.
For ductal carcinoma in situ (DCIS) treated with lumpectomy plus radiation, the review says a 2 mm margin appears to be as good as a larger one.
These numbers apply to breast cancer only. Other cancers use other standards, so ask your team what applies to yours.
What to Do With This Information
Read the margin section as a description, not a verdict. It records what the edge of one specimen looked like under a microscope. The decision about what happens next belongs to a wider conversation with your care team, including your imaging and the rest of your treatment plan.
If your report says positive and nobody has explained the plan yet, that is the question to bring to your next appointment.
Sources
Common questions
My margin is positive. Does that mean cancer was left behind?
NCI says a positive margin means cancer cells are at the edge of the tissue, which suggests some of the cancer has not been removed. Your surgeon reads the margin alongside what they saw during the operation. Ask what it means in your case.
Will I need another operation?
That depends on your cancer, which margin is involved, and the rest of your plan. Your care team decides this with you. Ask your surgeon what the options are, including more surgery, radiation or other treatment.
How close is too close?
The NCI fact sheet does not define a close margin. For invasive breast cancer treated with lumpectomy and radiation, an NIH-hosted review says the consensus standard is no tumor on ink. For DCIS it says 2 mm appears as good as a larger margin. Other cancers use other standards. Ask what your team is using.
Questions to ask your doctor
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Written by: Cancer ExplainedSources last checked: 2026-07-30 what this meansLast updated: 2026-10-16Next planned review: 2027-07-30
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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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