9-Week Cancer Treatment Keeps 32 Patients Disease-Free 3 Years

Thirty-two colorectal cancer patients received a nine-week immunotherapy treatment before surgery, and nearly three years later, not a single one has seen their cancer return.

The NEOPRISM-CRC trial, led by University College London and University College London Hospitals, tested a radically different approach to treating stage two and three colorectal cancer. Instead of the standard protocol of surgery followed by months of grueling chemotherapy, patients received pembrolizumab immunotherapy for just nine weeks before their operations.

The results have stunned researchers. After 33 months of monitoring, zero relapses have occurred among any of the 32 participants. This includes both patients whose tumors completely vanished and those who still had small traces of cancer remaining after treatment.

Compare that to the usual outcome: about 25% of patients treated with standard surgery and chemotherapy see their cancer come back within three years.

The trial focused on a specific genetic subtype of colorectal cancer called MMR deficient or MSI-high, which affects about 10 to 15% of stage two and three cases. In the UK alone, that represents roughly 2,000 to 3,000 patients every year who could potentially benefit from this approach.

Christopher Burston, a 73-year-old patient from Dorset, was among those who joined the trial after routine screening detected cancer in February 2023. He received the short immunotherapy course and now remains cancer-free.

What makes this breakthrough even more promising is the personalized blood testing researchers developed alongside the treatment. By analyzing blood samples for cancer DNA, doctors can now detect early whether the immunotherapy is working. When tumor DNA disappeared from the bloodstream, patients were far more likely to remain disease-free long term.

Dr. Kai-Keen Shiu, the trial's chief investigator and consultant medical oncologist at UCLH, explained the potential impact: "We now may be able to predict who will respond to the treatment using personalized blood tests and immune profiling. These tools could help us tailor our approach, identifying patients who are doing well and may need less therapy."

The research team also examined immune markers in tumor tissue before treatment began. These markers helped predict which patients would respond best, offering another tool for personalizing care.

Why This Inspires

This breakthrough represents hope for thousands of families facing a colorectal cancer diagnosis each year. Bowel cancer is the fourth most common cancer in the UK, with about 44,000 new cases annually, and rates among people under 50 have been rising.

The possibility of replacing months of difficult chemotherapy with just nine weeks of a different treatment, while achieving better results, could transform not just survival rates but quality of life during treatment. Patients might spend less time in treatment and more time living.

Professor Marnix Jansen from UCL Cancer Institute emphasized that the findings "not only confirm the durability of responses we saw almost three years ago, but also provide crucial biological insights into why immunotherapy is so effective in this setting."

The research team presented their latest findings at the American Association for Cancer Research Annual Meeting 2026 in San Diego.

For patients with this specific cancer subtype, a shorter, more effective treatment may soon become the new standard of care.