'Stable disease' on immunotherapy — is that actually good news?

Stable disease means your tumour measurements have neither shrunk enough to count as a response, usually a 30% or greater decrease, nor grown enough to count as progression, usually a 20% or greater increase or new lesions. It is one of four standard response categories — not an ambiguous or uncertain result.

The confusion is understandable: "stable" can sound like nothing is happening, when in fact it is a specific, deliberately defined category that oncologists use precisely because "nothing changed" and "something is wrong" are not the same finding. This page explains the general terminology used in these reports — it does not, and cannot, interpret your individual scan, which only your treating oncologist can do with your full history in front of them.

Based on RECIST 1.1 and iRECIST — the tumour-measurement frameworks referenced in NCCN and ASCO oncology reporting guidance. Your own oncologist applies these rules to your specific images; this table explains the categories, not your individual result.

It can be, and this is where immunotherapy genuinely differs from many other treatments. Stable disease that holds steady across two or more consecutive scans is increasingly recognised in oncology literature as a real, sometimes long-lasting form of disease control — not a lukewarm result stuck between success and failure.

With chemotherapy, oncologists have traditionally treated stable disease as a modest, transitional finding — a sign treatment is doing something, but not doing much. With checkpoint inhibitor immunotherapy, sustained stable disease is now discussed differently, sometimes as "durable stable disease," because the way immunotherapy works — training the immune system to keep suppressing the cancer over time — can show up on scans as a steady, unchanged picture rather than visible shrinkage, while still reflecting genuine, ongoing control. It is not automatically excellent news, and it is not automatically disappointing either; what matters most is whether the pattern holds over successive scans, not what any single scan says alone.

In most cases, yes — ongoing stable disease is generally treated as a reason to continue the current treatment plan, since it suggests the cancer is being kept in check rather than progressing. This is a decision for your oncology team, not a conclusion to draw from the word "stable" alone.

Continuing on the current schedule is the most common path when stable disease holds, but it is not automatic or unconditional. Your oncologist also weighs how long the stable pattern has lasted, your symptom trend, your side-effect burden, and any biomarker or blood test trends alongside the scan itself. Continuing, adjusting the dosing interval, or reassessing after one more confirmatory scan are all real, legitimate paths depending on your case — and where treatment is genuinely no longer tolerable, stopping or switching approach is also a real option to raise directly, not a failure.

They can look confusingly similar on a single scan, and immunotherapy is exactly why the distinction exists. Pseudoprogression is an early scan appearance of growth — sometimes immune cells gathering around the tumour — that a later scan shows was never true cancer growth at all.

Stable disease, by definition, is not growth at all — it is measurements that are unchanged or only slightly changed. Because early apparent progression on immunotherapy can occasionally turn out to be pseudoprogression rather than real disease growth, oncologists increasingly apply iRECIST criteria, which call for a confirmatory scan, typically four to eight weeks later, before a result is labelled true progression. See our dedicated explainer on how iRECIST measures response differently for immunotherapy for the full picture.

Response-assessment imaging such as PET-CT is coordinated for CION patients at partner imaging centres, not performed in-house — CION's oncology team reviews the resulting report and images together with you, rather than operating the scanner itself. This distinction matters because it affects who to contact for scheduling versus who to ask about the result.

If you're an existing patient, your care coordinator will confirm the partner centre, appointment slot, and any preparation needed for your specific scan type. Bring the report and images back to your oncology consultation — that combined review, not the scan report read alone, is what actually guides the next step in your treatment.

• Feeling Better but the Scan Looks Worse: Which Do You Trust? — the mirror-image confusion to this page, when the report and how you feel seem to disagree.
• Hyperprogression: When Cancer Accelerates on Treatment — the genuinely rare, opposite outcome a scan report needs to rule out.
• iRECIST: How Response Is Measured Differently for Immunotherapy — the full detail behind the unconfirmed-progression category explained above.
• Immunotherapy at CION Cancer Clinics — the full picture of how CION supports patients through response monitoring and follow-up decisions.

This page is for general information and explains standard scan-reporting terminology — it does not interpret your individual report. Response categories described here follow RECIST 1.1 / iRECIST as referenced in NCCN and ASCO oncology guidance; always review your own results with your treating oncologist.

Thousands have asked this exact question about their own report

Wanting a plain-language explanation instead of guessing is not overreacting — it's how informed patients stay on top of their own care. Our team walks through your specific report, honestly.