For decades, the standard playbook for treating stage two and three colorectal cancer has been straightforward: operate first, then hammer the patient with months of chemotherapy. It’s kept many alive, but it’s also been brutal. Now, a clinical trial led by researchers at UCL and UCLH suggests there might be a better way, and the early results are almost too good to believe.
The NEOPRISM-CRC study found that giving patients nine weeks of immunotherapy before surgery, rather than chemotherapy after it, produced something remarkable: not a single patient experienced a cancer recurrence after nearly three years of follow-up. In a world where roughly 25% of patients typically see their cancer return within three years under standard care, that’s a seismic shift.
When Cancer Disappears Before the Scalpel Touches It
Here’s what happened in the trial. Thirty-two patients with stage two or three colorectal cancer received pembrolizumab, an immunotherapy drug, for nine weeks leading up to surgery. The result was striking: 59% of patients had no detectable cancer after completing the immunotherapy and undergoing surgery.
But the real story emerged over time. When surgeons opened these patients up, they found something unexpected. Christopher Burston, a 73-year-old patient from Dorset who participated in the trial, described it perfectly. After being diagnosed with stage three bowel cancer in February 2023, he underwent three doses of immunotherapy before his surgery in May. When the doctors went in to operate, the cancer had essentially vanished.
“The outcome of the surgery was that the cancer had melted away,” Burston said, quoting his surgeon’s words. “The immunotherapy had had an almost immediate effect.”
Nearly three years later, Burston remains cancer-free. He’s not alone. None of the 32 patients in this trial experienced a relapse, including both those whose tumors completely disappeared and those who still had small traces of cancer remaining. The cancer simply stopped growing.
Blood Tests That Can Predict Who’ll Survive
What makes this trial even more intriguing is what researchers discovered along the way. They developed personalized blood tests that can detect whether cancer DNA is still circulating in a patient’s bloodstream after treatment. These tests could fundamentally change how doctors decide who needs aggressive follow-up treatment and who doesn’t.
According to Dr. Kai-Keen Shiu, Chief Investigator of the trial and a Consultant Medical Oncologist at UCLH, this opens a new door. “We now may be able to predict who will respond to the treatment using personalized blood tests and immune profiling,” he explained. “These tools could help us tailor our approach, identifying patients who are doing well and may need less therapy before and after surgery versus patients at higher risk of disease progression or relapse who need additional treatment.”
The first author of the study, Yanrong Jiang, reinforced this: when tumor DNA disappeared from the blood, patients were far more likely to remain cancer-free long term. This correlation between what the blood test showed and actual survival outcomes suggests we might finally have a window into which patients truly need intensive follow-up care.
Why This Matters for Science and Medicine
Bowel cancer is the fourth most common cancer in the UK, with about 44,000 new cases annually. Survival odds depend heavily on when it’s caught: around 90% of patients with stage one disease survive at least five years, but that plummets to 65% at stage three and just 10% at stage four.
The caveat here is important. This trial focused on a specific genetic subtype of colorectal cancer called MMR deficient/MSI-high, which accounts for about 10-15% of cases, or roughly 2,000-3,000 patients annually in the UK. This wasn’t a trial on all colorectal cancers. The results are encouraging for this population, but researchers will need to explore whether this approach works for other colorectal cancer types.
What researchers found, according to Professor Marnix Jansen from UCL Cancer Institute and UCLH, is that “immunotherapy is so effective in this setting” because of how it reshapes the immune response. The biology behind why pembrolizumab works here isn’t fully explained in the trial results, but the durability of the effect suggests something fundamental is being reset in the immune system.
The Practical Question: When Does This Reach Patients?
This is where the story gets complicated. These are compelling early findings from a 32-patient trial presented at the American Association for Cancer Research Annual Meeting in San Diego. That’s promising, but it’s not a green light. Regulatory approval typically requires larger, longer-term studies. Phase three trials are next, which will either confirm these results or reveal limitations we haven’t yet discovered.
Burston’s experience certainly sounds like a success story. His recovery was smooth, he had minimal side effects, and he’s returned to his normal routine. But one patient, or even 32 patients, doesn’t yet constitute a revolution in treatment. What it does represent is a genuine shift in thinking about the sequence of interventions.
The fact that no patients relapsed over three years is frankly unusual enough that it deserves serious attention from the wider oncology community. Whether that leads to changed clinical practice depends on what larger trials reveal and whether these results hold up in more diverse patient populations.
The real question now isn’t whether immunotherapy before surgery works for this specific cancer subtype. The trial has shown that convincingly. The question is whether doctors can accurately identify which patients will respond and which won’t, and whether we can afford the immunotherapy upfront for patients who might not need it. That’s where those blood tests become critical.
