The short answer
A mixed response means some sites shrink while others grow. Teams weigh how you feel, repeat imaging, and on immunotherapy must distinguish this from pseudoprogression before changing course.
A mixed or dissociated response means different sites of the same cancer are behaving differently — some shrinking, some stable, some growing.
Standard response criteria add up the measurements of a few selected lesions, so a mixed picture can be forced into a single label that does not describe what is really happening.
On immunotherapy, dissociated responses have been reported in roughly 3 to 9 percent of patients and are associated with better survival than true progression.
Pseudoprogression — apparent growth on a scan while treatment may be working — occurs in a small percentage of people on checkpoint inhibitors.
On this page
Choose how you want to read this
The whole article, with every detail and caution.
This page is for people whose scan shows some areas of cancer shrinking and others growing. It explains why this happens and what your care team may weigh next.
What the phrase describes
A mixed response, often called a dissociated response, means that different parts of the same cancer are doing different things at the same time. For example, two liver deposits (areas of cancer) have shrunk, while a lung nodule has grown. A lymph node has almost disappeared, while a bone lesion looks slightly larger.
This is a real and recognized pattern. It is not a fuzzy reading of the scan. And it is one of the harder results to be handed, because it refuses to be either good news or bad news.
Why one cancer behaves in several ways
A mixed response is a situation in which some tumors respond to treatment while others do not. This page does not claim to know why it happens in any one person. Your oncology team can tell you what they think is going on in your case.
Why the report may not say mixed response
Formal response criteria, such as RECIST (Response Evaluation Criteria in Solid Tumors), were built for clinical trials, where consistency matters more than nuance. Under RECIST 1.1, up to five lesions are chosen as targets. Their longest diameters are added together, and that sum is tracked over time. Partial response means the sum falls by at least 30 percent. Progressive disease means it rises by at least 20 percent, with an absolute increase of at least 5 millimeters, or that a new lesion has appeared.
A genuinely mixed picture gets pulled into whichever category the arithmetic produces. So what your radiologist describes in the body of the report may feel different from the single word in the conclusion. That is why the conversation with your oncologist matters more than the label.
The immunotherapy question that has to be asked first
If you are on a checkpoint inhibitor (a type of immunotherapy), apparent growth carries one extra possibility. A tumor can look larger on a scan even though the treatment may be working. This is called pseudoprogression.
It is uncommon. One review (in Frontiers in Oncology) reports it in roughly 1 to 9 percent of people on checkpoint inhibitors, depending on tumor type and drug.
That review also describes iRECIST, a set of imaging rules for immunotherapy. Under those rules, imaging that meets progression criteria is recorded as unconfirmed progressive disease, and a confirming scan is done at 4 to 8 weeks. Whether treatment continues in the meantime is your oncology team's decision.
The same review reports dissociated (mixed) responses in roughly 3 to 9 percent of people treated with checkpoint inhibitors, and says these patients had better overall survival than those with true progression.
What your team weighs
Several things beyond the images may go into the decision, including how you feel and your other test results. Do not try to judge this yourself from a scan report. Tell your team about any new or worsening symptoms. Call your care team right away for a fever of 100.4 F or higher, new severe pain, trouble breathing or any other symptom on the list your team gave you, and call 911 for an emergency.
The options that follow
The options depend on how many sites are growing, where they are, and how you are doing. They may include repeating the scan, taking a biopsy, or other steps your team will explain. This page does not say which is right for anyone, and nobody should stop or change treatment on their own. Ask your team directly which paths they are weighing, and what would tip them one way or the other.
Sources
Common questions
Is a mixed response good news or bad news?
It is genuinely in between, which is part of why it is hard to sit with. Something is working — the shrinking sites are evidence of that. Something else is not. In immunotherapy studies, people with dissociated responses did better on average than people with straightforward progression. It is not the clean result anyone hoped for, and it is not a failure of treatment either.
Why would parts of the same cancer behave differently?
A mixed response means some tumors respond to treatment while others do not. Why that happens in a particular person is a question for your oncology team.
What is pseudoprogression and how is it told apart from real growth?
On immunotherapy, a tumor can look larger on a scan even though the treatment may be working. This is called pseudoprogression. Under iRECIST, imaging that meets progression criteria is recorded as unconfirmed and a confirming scan is done at four to eight weeks. Your oncology team decides about treatment in the meantime.
Could just one growing spot be treated on its own?
That is a question for your oncology team. The answer depends on how many sites are growing, where they are, and how the rest of the cancer is behaving. Do not stop or change your treatment on your own.
Would a biopsy of the growing lesion help?
Your team decides that. NCI says that in most cases doctors need a biopsy to be certain that something is cancer. Ask whether a biopsy would change what happens next.
Questions to ask your doctor
Being prepared helps you get the most out of your appointments. Save or print these questions.
Tap a question to save it to your list (kept on this device).
More words from this kind of report
Other guides in stage, grade & treatment response.
Talk with a trained specialist or navigator
Cancer Explained provides educational guidance, but does not replace trained specialists, social workers, or your medical team.
Talk to a trained cancer information specialist
Free, confidential assistance from NCI Cancer Information Service via phone, chat, or email.
Contact your oncology team
Locate after-hours contact numbers, portal messages, or urgent triage phone lines.
Find a patient navigator
Get one-on-one help with appointments, logistics, translation, and care coordination.
Find a genetic counselor
Discuss inherited mutation risk, family history, and genetic testing options.
Find an oncology social worker
Access emotional counseling, family support groups, and mental health resources.
Find a financial navigator
Locate copay assistance foundations, grant programs, and lodging/travel support.
Find a clinical-trial specialist
Search matching studies and speak with NCI trial information specialists.
Get urgent help
Fever of 100.4°F (38°C) or higher during chemo, severe pain, or trouble breathing: call your cancer care team right away, day or night. Call 911 for an emergency.
Plain-language explanation of the published sources cited on this page. AI-assisted, source-checked, not clinician-reviewed.
Written by: Cancer ExplainedSources last checked: 2026-10-16 what this meansLast updated: 2026-10-16Next planned review: 2027-07-30
Review details and limits
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.
General education — varies by person. Answers genuinely differ between people. This page explains what commonly varies and points you to your care team 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.
Words to know
Tap any term to see what it means.
How this page was created
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.
Read more about our editorial process, our use of AI, and our corrections policy.
Spotted a problem? Report an error — a factual mistake, broken or outdated source, confusing wording, or anything that seems unsafe. Please do not include names, medical record numbers, dates of birth, addresses, or other identifying medical information in your report.
After using this page, do you understand what to do next?
Anonymous — we only record the answer, never who gave it.