New Findings on Colorectal Cancer Treatment

A recent clinical trial indicates that administering immunotherapy prior to surgery may significantly enhance outcomes for certain colorectal cancer patients. The NEOPRISM-CRC study has shown that individuals who received a brief course of immunotherapy instead of chemotherapy after surgical procedures have stayed cancer-free for nearly three years.

Impressive Outcomes

Conducted by researchers from UCL and UCLH, the trial revealed that just nine weeks of pembrolizumab treatment before surgery resulted in significant and lasting responses among patients with stage two or three colorectal cancer.

Initial results indicated that 59% of those who completed the immunotherapy and surgery had no detectable cancer. Now, after a follow-up period of 33 months, none of these patients have experienced a recurrence.

This includes patients whose tumors disappeared entirely as well as those who still had minor traces of cancer post-treatment. In all cases, the remaining cancer did not show signs of growth or spreading.

This is quite different from the usual care, where about 25% of patients treated with surgery followed by chemotherapy typically see their cancer return within three years. These findings imply that starting treatment with immunotherapy could offer a more sustainable form of protection.

Potential for Predicting Success

Researchers also looked into why this treatment method was effective and how to identify patients who might reap the most benefits. They developed personalized blood tests from analyzing samples, which can detect if cancer DNA persists in the bloodstream.

These tests might help doctors gauge the treatment’s success early on.

Dr. Kai-Keen Shiu, Chief Investigator of the trial, expressed optimism: “Seeing that no patients have experienced cancer recurrence after close to three years of follow-up is extremely encouraging and strengthens our confidence that pembrolizumab is a safe and highly effective treatment for patients with high-risk bowel cancers.”

He added, “What’s particularly thrilling is that we might now be able to predict treatment response using personalized blood tests and immune profiling. This could allow us to tailor our approach, identifying patients who are faring well and may require less therapy versus those at higher risk for disease progression who may need additional treatment.”

Insights into Bowel Cancer

Bowel cancer ranks as the fourth most prevalent cancer in the UK, with around 44,000 new cases diagnosed each year. It mainly affects older adults, though there’s been a noticeable increase in cases among people under 50.

Early detection significantly influences survival rates: roughly 90% of patients diagnosed at stage one survive for at least five years, while survival rates drop to 65% at stage three and plummet to just 10% at stage four. Some tumor types are also less responsive to treatment and more likely to recur.

Trial Participants

The NEOPRISM-CRC trial involved 32 patients with stage two or three colorectal cancer, specifically a genetic subtype (MMR deficient/MSI-high bowel cancer) that represents about 10-15% of such cases in the UK, equating to roughly 2,000-3,000 patients annually.

Participants underwent up to nine weeks of pembrolizumab treatment prior to surgery, instead of the usual method of surgery followed by several months of chemotherapy. They were monitored closely over time.

These findings were recently presented at the American Association for Cancer Research (AACR) Annual Meeting 2026 held in San Diego. Multiple UK hospitals participated in the study, with UCL and UCLH at the forefront and the biotech company Personalis aiding in the analysis.

Understanding Treatment Efficacy

Research has also shed light on how immunotherapy produces these enduring effects.

Professor Marnix Jansen from UCL Cancer Institute noted, “These results not only confirm the durability of responses we observed almost three years ago, but also provide important biological insights into why immunotherapy is so effective in this context.”

Researchers found that when tumor DNA disappeared from the bloodstream, patients were much more likely to stay cancer-free in the long run.

Yanrong Jiang, the study’s first author, commented, “As a research team, we were excited to closely monitor patients with personalized blood tests. When the tumor DNA was absent from the blood, patients were much more likely to have no remaining cancer, aligning with the long-term outcomes we’re currently witnessing.”

He added, “Additionally, we noted that profiling the tumor tissue before treatment could help predict how well patients respond. Our hope is that these tests can inform treatment decisions more effectively.”

Real-Life Experiences

Christopher Burston, a 73-year-old from Portland, Dorset, was diagnosed with colorectal cancer in February 2023 after routine screening identified blood in his stool.

He recounted, “One test came back indicating blood in my stool. Further tests led to a colonoscopy where they discovered cancer in my bowel.”

Shortly after his diagnosis, he was offered the opportunity to participate in the NEOPRISM trial and chose to join, making trips to London for treatment.

He received three doses of immunotherapy over a nine-week span before surgery in May 2023. His recovery was smooth, with minimal side effects.

He reflected, “The surgery outcome was remarkable—essentially, the cancer had melted away, as the doctor put it. The immunotherapy had an almost immediate effect. When I saw the images from my initial colonoscopy, the lump had been significant. I was diagnosed with stage three cancer.”

Now, nearly three years later, he remains cancer-free and has resumed his normal life.

Christopher shared, “The recovery was seamless. I didn’t have any issues. Now, I feel much like my old self again, and I’m grateful that my main focus is aging rather than dealing with cancer or illness.”