A closer look · Treatment response
What does a
scan result mean?
Explore five fictional patterns. Compare what happens to selected areas of cancer with what the whole assessment tells us.
Teaching examples, not scans. The circles below are symbols. Their size is not a measurement, a RECIST calculation or an image of a person’s cancer. Each explanation states the assumptions for that fictional assessment.
Before and afterSymbolic, not to scale
Circle outlines identify selected areas, not anatomical sites. Disappearing symbols mean no remaining evidence on the assessment used in that example, not proof that every cancer cell is gone.
Example / Partial response
Smaller, but not gone.
Assume the measured disease has decreased enough to meet the response criteria used. There is no confirmed new cancer site and no other finding that makes the overall assessment progression.
This fictional pattern illustrates a partial response. Some cancer remains detectable. It does not mean that every tumour has shrunk by the same amount.
The explanation supplies the assessment. The drawn circles do not calculate it.
Example / Stable disease
Little change can still matter.
Assume the measured changes are not enough to qualify as partial response or progressive disease, with no other finding that establishes progression.
This illustrates stable disease. In a treatment aimed at controlling cancer, preventing meaningful growth can be useful. Symptoms, side effects and how long control lasts also matter.
“Stable” is a response description, not a verdict on whether treatment is worthwhile.
Example / Complete response
No remaining evidence
on this assessment.
Assume all cancer being assessed has resolved according to the relevant method and criteria. The symbols disappear to illustrate that result.
That does not prove that every cancer cell has gone, guarantee that cancer will not return or remove the need for appropriate follow-up. Criteria and confirmation requirements vary.
A complete response is not automatically the same as cure.
Example / Progressive disease
Smaller here.
A new site elsewhere.
The selected areas have become smaller. But, in this fictional assessment, a new cancer site has been confirmed and makes the overall result progressive disease.
An uncertain spot on a scan is not automatically a confirmed new cancer site. Clinical interpretation and sometimes further assessment are needed. Some treatments also use modified response criteria.
Shrinking selected tumours alone does not establish the overall response.
Example / Mixed changes
Different areas can
behave differently.
One selected area is smaller, one is larger and one is similar. This illustration does not provide measurements, a full disease assessment or enough information to assign a formal overall category.
“Mixed changes” describes a pattern; it is not a separate formal RECIST response category. The oncology team considers all findings and the clinical situation.
This display cannot decide whether to continue, change or stop treatment.
What else belongs in the assessment?
More than selected measurements
Assessment may include disease that cannot be measured in a simple way, possible new sites, symptoms, examination and relevant blood tests. The useful information depends on the cancer and treatment.
More than one comparison
The reference point and timing matter. Formal systems such as RECIST have detailed rules; assessment of progression can involve the smallest previous measurements, not just the first scan. This lesson does not implement those rules.
A response label contributes to a clinical discussion. It does not automatically determine the next treatment step.
Pause and consider
If one selected tumour is smaller, is that enough to call the whole result a partial response?
No. The full assessment can include other disease, new findings and the response criteria being used. The “confirmed new site” example illustrates why the wider picture matters.
Read more
Sources & clinical review
Clinically reviewed and approved by Dr AlHilali on 4 November 2026.
- RECIST Working Group: RECIST 1.1 — formal measurement and overall-assessment context; this lesson is not a RECIST calculator.
- NCI: partial response and stable disease.
- Existing approved DrAlHilali.com response, stable-disease and treatment-assessment articles provide the detailed clinical context.