Christopher Burston was 73 years old when he was diagnosed with bowel cancer in February 2023. Instead of the usual surgery and months of chemotherapy, he received three doses of a drug over nine weeks, followed by surgery in May. Three years later, he remains cancer-free.
Burston is one of 32 patients in NEOPRISM-CRC, a UK trial whose results were presented at the American Association for Cancer Research Annual Meeting 2026 in San Diego. After nearly three years of follow-up, not a single patient has experienced a cancer relapse. This is remarkable because roughly one quarter of comparable patients normally relapse within three years under standard treatment.
The trial focused on a specific type of bowel cancer called mismatch-repair-deficient, or MSI-high. These tumours have broken DNA-repair machinery, which makes them easier for the immune system to recognize and attack. Patients received pembrolizumab, an immunotherapy drug that activates the body's T cells. In 59 percent of patients, surgeons found no detectable cancer before surgery. After surgery, blood tests showed that circulating tumour DNA was undetectable in every evaluable patient.
Bowel cancer is the fourth most common cancer in the UK, with about 44,000 new cases yearly. The MSI-high subgroup accounts for between 2,000 and 3,000 cases annually. This trial demonstrates that pembrolizumab could significantly improve outcomes for high-risk bowel cancer patients.