Bowel Cancer Immunotherapy Before Surgery: No Relapses After 33 Months in a Small UK Trial

A press release from University College London (UCL), reposted by ScienceDaily on October 10, 2026, says that people with one genetic type of bowel cancer who had immunotherapy before surgery have stayed free of cancer for almost three years. The results were first presented at the American Association for Cancer Research (AACR) Annual Meeting in April 2026. This page sums up what was reported and what it does and does not mean.

What was reported

The trial is called NEOPRISM-CRC. It is led by UCL and University College London Hospitals (UCLH) and ran at five UK hospitals. According to the press release and two reports of it:

• Who: 32 people with stage 2 or stage 3 bowel cancer whose tumors were "MMR deficient" or "MSI-high," a genetic profile also called dMMR/MSI-H. The release says about 10 to 15 percent of stage 2 and 3 bowel cancers have this profile.
• What: up to nine weeks of the immunotherapy drug pembrolizumab before the planned bowel operation, instead of chemotherapy after it.
• Earlier result: 59 percent of the 32 had no signs of disease in the tissue removed at surgery.
• New result: after 33 months of follow-up, none of the treated people had a relapse.
• The comparison: the release says "around 25% of patients treated with the standard approach of surgery followed by chemotherapy are expected to relapse within three years."

Dr. Kai-Keen Shiu, the chief investigator, said: "Seeing that no patients have experienced a cancer recurrence after almost three years of follow-up is extremely encouraging." One participant, Christopher Burston, 73, said the surgery showed "essentially that the cancer had melted away." The team also said blood tests and immune profiling may help predict who will respond.

What this can and cannot tell us

Zero relapses in 32 people is striking. It is also a small number, and there are limits on what it can show:

• No comparison group. Everyone in the trial got the same treatment. The 25 percent figure is the rate expected in other patients, not the result of treating a matched group the usual way. We could not find a head-to-head comparison in the sources we opened.
• Small and early. Thirty-two people followed for about 33 months is promising, but a late relapse can still happen, and a small study can miss rarer problems.
• "No relapse" is not "cured." The researchers report no recurrence so far. They do not say these people are cured.
• Only one genetic type. This applies to the 10 to 15 percent of stage 2 and 3 bowel cancers that are MMR deficient or MSI-high. It says nothing about the large majority of bowel cancers that are not. Our pages on what MSI-H means and what dMMR means explain these report terms.
• Not a new standard yet. The press release and reports we read do not say that doctors should change usual care because of this trial. Our page on how to read clinical trial results lists the questions to ask about any trial.

We could not find the funding source or the safety results in the sources we opened, so we cannot report them.

What immunotherapy can do to the body

Pembrolizumab is a checkpoint inhibitor. The National Cancer Institute (NCI) says these drugs work by "blocking checkpoint proteins from binding with their partner proteins," which lets T cells "kill cancer cells." NCI lists rash, diarrhea and fatigue as common side effects. It says rarer effects can include widespread inflammation that affects organs such as the heart, liver and nervous system. Our pages on checkpoint inhibitors and immune-related side effects cover this in more detail.

If you or someone you love has bowel cancer

• Whether this kind of treatment is an option depends on the tumor's genetic profile, its stage and the person's health. That is a conversation for your cancer team, who have your test results. Our page on MSI-H colorectal cancer lists questions to bring.
• If you are on immunotherapy now, call your care team the same day about new diarrhea, a new rash or unusual tiredness. Call right away for any fever of 100.4°F (38°C) or higher, and at any hour.
• Call 911 or go to an emergency room for trouble breathing, chest pain, severe belly pain, black or bloody stools, or sudden confusion or weakness. Do not drive yourself.

Sources

• ScienceDaily, "Bowel cancer 'melted away' after immunotherapy, then stayed away" (UCL press release): sciencedaily.com
• News-Medical, "Trial shows durable response with preoperative immunotherapy in bowel cancer," April 20, 2026: news-medical.net
• ecancer, "AACR 2026: Groundbreaking bowel cancer trial follow-up shows zero relapses," April 21, 2026: ecancer.org
• ClinicalTrials.gov registration number for NEOPRISM-CRC, NCT05197322 (the record itself did not open for us): clinicaltrials.gov
• National Cancer Institute, "Immune Checkpoint Inhibitors": cancer.gov

UCL's own page for the release (ucl.ac.uk) and the ClinicalTrials.gov record would not open for us, so the figures above come from ScienceDaily's repost and the two news reports of it, and we used only the trial's registration number from ClinicalTrials.gov. We did not read the AACR abstract or a peer-reviewed paper.

How this article was prepared

An AI-assisted editorial system helped prepare this page. It used a UCL press release reposted by ScienceDaily, two news reports of the AACR presentation and an NCI page on checkpoint inhibitors. No named medical reviewer has reviewed it unless one is listed.

Cancer Explained is published by the National Cancer Information Foundation. It is not medical advice and does not suggest a test or treatment.

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