When the Scan After Cycle 6 Says “No Significant Change” — Why Stable Size Is Not the Same as Failure in Colorectal Liver Metastases, and What Actually Decides Whether Surgery Is on the Table

When cancer that began in the colon has spread to several places in the liver, every round of imaging comes back to the same question: did it shrink? Often the answer in clinic is only “no significant change from baseline.” Whether that sentence means the drugs are not working, or means the current plan should simply continue, cannot be settled by one number. Several separate factors have to be read together.

It helps to know the rulebook behind the report. Response in solid tumours is usually scored with RECIST (Response Evaluation Criteria in Solid Tumors): a few representative lesions are chosen, their longest diameters are added up, and the sum is compared with the previous scan. A drop of 30% or more is a partial response, a rise of 20% or more is progression, and anything in between is recorded as stable disease. “No significant change” usually lands in that middle band — and stable disease is not a synonym for failure. It can also describe a disease that would have grown if left alone and is instead being held in place.

Size alone also misses part of the picture. When an anti-angiogenic drug is part of the regimen, tumours sometimes respond by breaking down internally before the outer measurement moves. Words in the report such as necrosis, cystic change, or decreased enhancement can mean the inside is changing even while the diameter holds. Reading the narrative section of the radiology report, not only the millimetres, gives a better basis for the next conversation.

Most importantly, the question of whether liver metastases can be removed is not decided by percentage shrinkage. What surgical teams weigh is the volume and function of the liver that would remain after resection, how closely the lesions sit against major vessels such as the portal and hepatic veins, whether disease is confined to one lobe or scattered across both, and whether anything has spread outside the liver. Favourably placed lesions can be resectable without much shrinkage; heavily shrunken lesions can still be unresectable if too little liver would remain, in which case a staged approach — growing the future remnant first — may be discussed. A small lung nodule of uncertain nature is usually clarified as part of that same sequence.

There is also a reason chemotherapy aimed at making surgery possible is not extended indefinitely. Prolonged oxaliplatin can injure the small vessels of the liver, and prolonged irinotecan can drive fatty change resembling steatohepatitis; both make recovery after resection harder. Lesions that disappear on imaging may still contain viable cells, leaving the surgeon without a target. So teams try to place the operation near the point of best response. If an anti-angiogenic agent is being given, it typically has to be paused for some weeks before surgery because of wound healing and bleeding, which is why the chemotherapy calendar is rebuilt once a date is set.

Before a multidisciplinary meeting, one page in chronological order makes the discussion sharper: lesion measurements at each scan, the trend in markers such as CEA, any drug that was reduced or omitted for side effects and when, changes in weight and daily activity, and how many days vomiting lasted. If scans were done elsewhere, send the actual images, not just the written report, so the same measurements can be compared.

A short list of questions is worth drafting too: which response category the team is using now, how many more cycles of this combination are planned, whether size, location, or remnant liver volume is the obstacle to surgery, when and how the lung nodule will be characterised, and whether changing or adding an agent is an option.

One note for family caregivers who ask why it was not caught sooner: cancers on the right side of the colon often declare themselves late, because stool is still liquid there and the first signals tend to be vague — anaemia, fatigue. The timing of a diagnosis is not a measure of how attentive anyone was.

This article is general information and does not replace individual diagnosis or care. Any decision about treatment plans, scan timing, or stopping or changing a drug should be made together with your medical team.