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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The full explanation.
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. Scans look clear, and any measures the team was tracking have returned to normal. It is welcome news and a sign the treatment worked well.
But "undetectable" is not the same as "gone forever." Tiny amounts of cancer too small to show up on tests can still be present, which is why your team continues follow-up even after a complete response. A lasting complete response over time becomes more and more reassuring.
What a partial response means
A partial response means the cancer has shrunk by a meaningful amount but has not disappeared. This is also a good sign — it shows the cancer is sensitive to the treatment you are receiving. 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 it means for your plan, whether treatment continues or changes, and how your response will be checked going forward. Your care team can translate the term into what happens next for you.
Words to know
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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. A complete response means the cancer cannot be detected on current tests, but tiny amounts too small to see may still be present. That is why follow-up continues. Over time, a lasting complete response is reassuring, but 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. It shows the cancer is sensitive to what you are receiving.
▸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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Your next step
Plain-language definitions for both sides of the comparison.
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