Colon cancer is the third most prevalent form of cancer in the U.S., and while screening has helped detect and prevent colon cancer from spreading, major advancements in treating colon cancer have lagged.
Now, new research led by Mayo Clinic Comprehensive Cancer Center found that adding immunotherapy to chemotherapy after surgery for patients with stage 3 (node-positive) colon cancer - and with a specific genetic makeup called deficient DNA mismatch repair (dMMR) - was associated with a 50% reduction in cancer recurrence and death compared to chemotherapy alone. Approximately 15% of people diagnosed with colon cancer exhibit dMMR and, to date, these tumors appear less sensitive to chemotherapy. The results of the multi-center study were presented during a plenary session at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago.
"The findings from our study represent a major advance in the adjuvant treatment of dMMR stage 3 colon cancer and will now change the treatment for this type of cancer," says oncologist Frank Sinicrope, M.D., who led the study. "It's extremely rewarding to be able to offer our patients a new treatment regimen that can reduce the risk of recurrence and improve their chances of survival."
Until now, the standard treatment after surgery for any stage 3 colon cancer has been chemotherapy. However, the researchers note that approximately 30% of patients experience cancer recurrence despite this treatment.
Watch: Dr. Frank Sinicrope discusses Mayo Clinic immunotherapy study
