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Bowel cancer “melted away” after immunotherapy, then stayed away

A brief course of pre-surgery immunotherapy may provide long-lasting protection against relapse for some patients with certain stages of bowel cancer, according to early trial results with pembrolizumab.

NeoMD Editors · 2026-10-12 · 12:21 PM EDT

For information, not personal medical advice. Discuss treatment decisions with a qualified clinician.

The quick read

Key takeaways

A trial with 32 patients with stage 2 or 3 bowel cancer and a specific genetic marker showed that pembrolizumab immunotherapy given before surgery prevented cancer recurrence over almost three years.
None of the patients had cancer returning after nearly three years, including those with small traces of cancer detected after immunotherapy but before surgery.
The study suggests pembrolizumab before surgery could replace post-surgery chemotherapy in some patients, potentially reducing side effects and improving quality of life.

Editorial illustration for Bowel cancer “melted away” after immunotherapy, then stayed away — AI-generated editorial illustration.

Researchers studied a group of 32 patients with stage two or three bowel cancer characterized by a specific genetic marker. Instead of the typical approach of giving chemotherapy after surgery, these patients received the immunotherapy drug pembrolizumab for up to nine weeks before their surgery.

After almost three years of monitoring, none of these patients experienced cancer returning. This included individuals who still had small traces of cancer detected after their immunotherapy treatment prior to surgery.

What was studied?

The trial, named NEOPRISM-CRC, tested if giving pembrolizumab, an immunotherapy that stimulates the immune system to attack cancer, before surgery could be effective for certain bowel cancers. This immunotherapy was given over a short period of up to nine weeks, replacing the standard post-surgery chemotherapy used in these stages.

What is the evidence?

Supporting editorial illustration for Bowel cancer “melted away” after immunotherapy, then stayed away — AI-generated editorial illustration.

The evidence comes from this clinical trial involving 32 patients, all with bowel cancers having a specific genetic form. The report notes that at nearly three years of follow-up, none of the patients had cancer recurring. This suggests a durable benefit from the immunotherapy given before surgery.

What are the limitations?

The study involved a small number of patients, which limits how confidently the results can be applied to all bowel cancer patients. Also, the trial focused on cancers with a particular genetic feature, so the findings may not apply to other bowel cancers. Long-term effects beyond three years remain unknown, and further research is necessary to confirm these findings and understand any risks or side effects.

What could this mean?

If confirmed, a short course of immunotherapy before surgery could offer some bowel cancer patients excellent protection against relapse without needing the usual chemotherapy afterward. This could mean fewer side effects and improved quality of life during treatment.

Source: ScienceDaily Medical