Why Did My SUV Go Up — After Treatment?

A higher SUV after treatment is not automatically a sign of progression. The number measures metabolic activity, not cancer cells directly, and dying tumour cells, inflamed tissue, and recovering bone marrow can all raise it temporarily. Your oncologist reads the result alongside your baseline scan, the timing of the test, and your clinical symptoms before drawing any conclusion. A single higher number is the beginning of a conversation with your team, not a verdict on its own.

A metabolic flare is not itself dangerous — it is a temporary biological effect caused by cells in the process of dying. It can be alarming to read on a report because the number looks worse before it reflects the actual treatment response. The flare does not require additional treatment. What matters is whether your team can attribute the rise to a flare rather than to progression, which is a judgement they make based on timing and the full scan pattern.

They look at several things together: when the scan was taken relative to treatment, whether new lesions have appeared anywhere, how other lesions in the body have behaved, and how you feel. A rise confined to known lesions in a patient who otherwise feels better looks very different from a rise accompanied by new lesions and worsening symptoms. When the picture is genuinely ambiguous, a repeat scan after a planned interval is often recommended rather than an immediate treatment change.

Yes. Chemotherapy and radiation cause inflammation in treated tissue, and inflamed tissue absorbs more tracer. This means that lesions responding to treatment can temporarily show a higher SUV rather than a lower one. It is one of the reasons ASCO and ESMO response assessment guidelines recommend specific waiting intervals between treatment and scanning, so that the reading reflects the tumour's actual state rather than an acute inflammatory response to the treatment itself.

A mixed response — where some lesions improve and one does not — is something your oncologist will examine carefully. It does not automatically mean treatment has failed. Your team will consider whether the area that rose is an established lesion or a new one, how large the change is, and whether the pattern fits inflammation or flare rather than progression. Bring the specific lesion location to your oncologist so they can address it against your actual report and the full clinical picture.

Ask three things: what they believe caused the number to rise, whether any new lesions appeared or only existing ones changed, and what the plan is — including whether a repeat scan is being considered. It is also reasonable to ask for the comparison between your baseline and current scan to be explained in plain language. These conversations are hard to remember clearly afterwards, so write down the answers or bring someone with you who can.