The short answer
A complete response means tests can no longer detect the cancer. A partial response means the cancer has shrunk by a meaningful amount but some remains. Both mean treatment is working. These terms describe what tests show at a point in time, not whether a cancer is cured.
A complete response means no cancer can be detected on scans or tests.
A partial response means the cancer shrank by a meaningful amount but some is still there.
Both are signs that a treatment is working.
A complete response is not the same as a cure; it means the cancer is undetectable at that moment, and follow-up continues.
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This page is for people who have heard the terms "complete response" or "partial response" after a scan or test. It explains what each term means and what it does not mean.
The short version
These terms describe how much a cancer has responded to treatment, based on tests at a point in time. A complete response means no cancer can be detected on scans or tests. A partial response means the cancer has shrunk by a meaningful amount but some remains. Both mean the treatment is working. A complete response is not the same as a cure — it means the cancer is undetectable right now, and follow-up continues.
What a complete response means
A complete response — sometimes called a complete remission — means that after treatment, tests can no longer find any sign of the cancer. NCI defines it as the disappearance of all signs of cancer in response to treatment. It is welcome news and a sign the treatment worked well.
But NCI also says a complete response does not always mean the cancer has been cured. That is why follow-up care continues after treatment, with regular check-ups and tests, and why you should tell your team about any new symptoms.
What a partial response means
NCI defines a partial response as a decrease in the size of a tumor, or in the extent of cancer in the body, in response to treatment. The cancer has shrunk but has not disappeared. This is also a good sign that the treatment is having an effect. Depending on the goal of your plan, your team may continue the same treatment, add to it, or reassess after more time. A partial response is progress, not a setback.
The other words you may hear
Doctors use a small set of terms to describe results:
- Stable disease: the cancer has not grown or shrunk much.
- Progression: the cancer has grown or spread despite treatment.
Along with complete and partial response, these help your team describe how things are going and decide on next steps. None of them is a final verdict — they are checkpoints along the way.
Putting it in context
Response terms are snapshots, not the whole story. What matters is the trend over time and what your team recommends next. If you hear one of these words, it is fair to ask:
- What does it mean for my plan?
- Will treatment continue or change?
- How will my response be checked going forward?
Your care team can translate the term into what happens next for you.
Sources
Common questions
What is the difference between a complete and partial response?
A complete response means tests can no longer detect any cancer. A partial response means the cancer has shrunk by a meaningful amount but some remains. Both indicate that the treatment is having an effect.
Is a complete response the same as being cured?
No. NCI says a complete response does not always mean the cancer has been cured. Follow-up care continues after treatment, and the words 'response' and 'cure' are not the same.
Is a partial response bad news?
Not at all. A partial response means the treatment is shrinking the cancer, which is a good sign. Depending on the goal, your team may continue the treatment, add to it, or reassess.
What are stable disease and progression?
Stable disease means the cancer has not grown or shrunk much. Progression means the cancer has grown or spread. Along with complete and partial response, these terms help your team describe how treatment is going and decide on next steps.
Questions to ask your doctor
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Plain-language explanation of the published sources cited on this page. AI-assisted, source-checked, not clinician-reviewed.
Last 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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