Christopher Burston was diagnosed with stage three bowel cancer in February 2023, after a routine screening kit sent to his home in Dorset came back positive. By May that year, three months on, he had received his treatment and had his surgery. He has not needed chemotherapy since, and almost three years later, remains cancer-free.
That timeline, roughly three months from diagnosis to recovery rather than the six or more months a standard course of post-surgical chemotherapy typically demands, sits at the centre of new results from the NEOPRISM-CRC trial, led by UCL and UCLH, presented this year at the American Association for Cancer Research (AACR) Annual Meeting in San Diego.
Patients with a specific bowel cancer who were given short-course immunotherapy before surgery, instead of post-op chemotherapy, remained cancer-free after nearly three years of follow-up, according to the trial’s own account.
It is worth mentioning that this is data presented at a scientific conference, not yet a peer-reviewed published paper, and the claims below are UCL and UCLH’s own account of their research rather than independently adjudicated results.
The trial tested a different order of operations for a specific subset of bowel cancer patients.
Patients were given up to nine weeks of pembrolizumab prior to bowel surgery, instead of the usual treatment of surgery followed by three to six months of chemotherapy, then monitored over time.
Initial results, reported after the treatment and surgery, indicated that 59% of patients had no signs of disease at all. That figure is the difference Burston’s own case illustrates: for those patients, the tumour had effectively gone before chemotherapy would even have started under the old approach. The number that has drawn attention now is not the initial response rate but what happened afterwards, or rather, what didn’t.
Now 33 months later, none of the treated patients have experienced a return of their cancer, including those who had no signs of cancer after treatment and those who still had small amounts remaining, which did not grow or spread during follow-up.
A more detailed breakdown of the same data, presented at AACR and reported by the oncology trade publication OncLive, put the median follow-up at 32.9 months, with a data cutoff of 31 March 2026, and recorded no relapses among the 31 patients tracked for recurrence. The same report noted the treatment’s safety profile: serious, grade three or four immune-related side effects occurred in only two of the 32 patients enrolled, a rate of 6.2%.
Around 25% of patients who have standard surgery and post-operative chemotherapy are expected to relapse after three years, and the NEOPRISM-CRC results suggest that a short course of neoadjuvant immunotherapy can provide more durable, long-lasting cancer control for stage two and three bowel cancer, compared with surgery and chemotherapy.
A quarter of patients relapsing is the baseline this trial is being measured against, not an abstract statistic.
The trial only applies to a specific slice of bowel cancer patients, and that specificity is part of why it worked.
The NEOPRISM-CRC trial recruited 32 patients with stage two or three bowel cancer and a certain genetic profile, MMR deficient or MSI-high bowel cancer, from five hospitals around the UK, a genetic make-up shared by around 10 to 15% of patients with stage two or three bowel cancer, representing around 2,000 to 3,000 cases per year in the UK.
That genetic marker indicates a tumour with a faulty DNA repair mechanism, which tends to make it unusually visible to the immune system once a checkpoint inhibitor like pembrolizumab is introduced, which is why this particular subgroup was selected rather than bowel cancer patients generally.
Alongside the survival figures, the research team built a diagnostic tool that let them watch the treatment work in something close to real time.
Researchers analysed blood samples to better understand why the treatment is so effective and how to identify those most likely to benefit, designing personalised blood tests that can show early on whether the treatment had worked and whether any cancer was still present in the bloodstream.
Rather than waiting months to discover whether a patient’s cancer has returned, doctors can track fragments of tumour DNA circulating in the blood and get an early signal.
Bowel cancer remains common enough that a genuinely durable alternative to standard treatment matters at scale. It is the fourth most common cancer in the UK, with around 44,000 cases a year, and though it still predominantly affects older people, cases among the under 50s have been increasing in recent decades.
Caught early, the outlook is generally good: nine in ten patients treated for stage one bowel cancer survive for five years or more, but specific sub-types of tumours don’t respond as well to treatment and are more likely to return, with five-year survival falling to 65% in stage three and 10% in stage four.
The trial itself continues to follow its patients.
Its latest work, outlined at AACR in San Diego, was led by UCL and UCLH, with University Hospital Southampton, St James’s University Hospital in Leeds and the Christie NHS Foundation Trust in Manchester involved in recruiting patients and providing translational samples, while all translational work was carried out by UCL and the biotechnology company Personalis.
Whether these results hold once formally peer-reviewed and tested in a larger trial is the open question that will determine whether this approach becomes standard treatment rather than a promising early signal, but for the 32 patients followed so far, the arithmetic of nine weeks against six months has already changed what recovery looked like.
The next real test for this treatment is peer review and a larger trial, and EyeOnLondon will be watching whether UCL’s nine-week alternative becomes standard NHS practice or stays a promising outlier.
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