9-Week Immunotherapy Before Surgery Keeps Colon Cancer Patients Relapse-Free for 3 Years
A short pre-surgery course of pembrolizumab left zero relapses in colorectal cancer patients after 33 months — reshaping treatment strategy.
Summary
A UK clinical trial found that nine weeks of immunotherapy before surgery produced remarkable results in a specific type of colorectal cancer. In the NEOPRISM-CRC study, patients with MMR-deficient colorectal cancer received pembrolizumab prior to surgery instead of the standard post-surgery chemotherapy. After 33 months of follow-up, not a single patient had experienced a cancer recurrence. This compares favorably to standard care, where roughly 25% of similar patients relapse within three years. Researchers also developed personalized blood tests to detect residual cancer DNA, potentially allowing doctors to tailor treatment intensity based on individual response. The findings suggest flipping the treatment order — immunotherapy first, surgery second — could offer significantly stronger and more durable protection for eligible patients.
Detailed Summary
Colorectal cancer treatment may be on the verge of a significant shift, thanks to new clinical trial results from University College London. The NEOPRISM-CRC trial tested whether giving immunotherapy before surgery — rather than chemotherapy after — could improve outcomes for patients with a genetically distinct subtype of bowel cancer known as MMR-deficient or MSI-high colorectal cancer.
The results are striking. Among 32 patients with stage two or three colorectal cancer who received just nine weeks of pembrolizumab before surgery, none have experienced a cancer recurrence after nearly three years of follow-up. By comparison, standard care — surgery followed by months of chemotherapy — sees roughly 25% of patients relapse within the same timeframe. Early in the trial, 59% of patients showed no detectable cancer after completing immunotherapy and undergoing surgery, but even those with residual cancer saw no progression.
A key secondary finding involves personalized blood-based diagnostics. Researchers developed tests capable of detecting circulating tumor DNA in the bloodstream, offering a potential early signal of whether treatment is working. This could allow oncologists to identify patients who need more aggressive follow-up versus those who may safely reduce therapy — a meaningful step toward precision oncology.
The practical implications extend beyond this specific subtype. MMR-deficient colorectal cancer accounts for 10–15% of stage two and three cases, meaning tens of thousands of patients globally could potentially benefit if these results hold in larger trials. Bowel cancer is the fourth most common cancer in the UK, with 44,000 new diagnoses annually, and survival drops sharply with advancing stage.
Important caveats apply. The trial enrolled only 32 patients, making it a small early-phase study. Larger, randomized controlled trials are needed before this approach becomes standard care. Nonetheless, the zero-relapse outcome at 33 months is a clinically meaningful signal that warrants urgent follow-up research.
Key Findings
- Zero cancer relapses recorded after 33 months in patients given pre-surgery pembrolizumab immunotherapy.
- 59% of patients showed no detectable cancer after completing immunotherapy before surgery.
- Standard post-surgery chemotherapy sees roughly 25% relapse within three years — immunotherapy may outperform it.
- Personalized blood tests detecting tumor DNA could predict treatment success and guide therapy intensity.
- MMR-deficient colorectal cancer affects 10–15% of stage 2–3 patients, representing a sizable eligible population.
Methodology
This is a news summary of the NEOPRISM-CRC clinical trial led by UCL and UCLH, reported via ScienceDaily. The source institution is credible and the trial represents prospective clinical evidence, though the study is small (n=32) and likely early-phase without a randomized control arm. Primary peer-reviewed publication should be consulted for full methodology and statistical detail.
Study Limitations
The trial included only 32 patients, limiting statistical power and generalizability. No randomized control group was used, making direct causal comparison to standard care difficult. Longer follow-up and larger phase III trials are needed before this protocol can be recommended as standard clinical practice.
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