Breakthrough in Colon Cancer Treatment: Immunotherapy Combines with Chemotherapy for Improved Outcomes

Researchers from the Mayo Clinic have made a significant breakthrough in the treatment of stage 3 colon cancer, a disease that is the third most prevalent form of cancer in the U.S. According to recent research, adding immunotherapy to chemotherapy after surgery for patients 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. This combination of treatments is considered a major advance in the adjuvant treatment of dMMR stage 3 colon cancer and will now change the treatment for this type of cancer.

Key Takeaways:

• The study found that adding immunotherapy to chemotherapy after surgery for patients with dMMR stage 3 colon cancer resulted in a 50% reduction in cancer recurrence and death compared to chemotherapy alone.
• Approximately 15% of people diagnosed with colon cancer exhibit dMMR, and these tumors appear less sensitive to chemotherapy.
• The study enrolled 712 patients with dMMR stage 3 colon cancer that had been surgically removed and who had cancer cells in their lymph nodes.
• The immunotherapy used in the study was an immune checkpoint inhibitor, atezolizumab, which activates the immune system to attack and kill cancer cells.
• The patients received chemotherapy for six months along with immunotherapy and then continued with immunotherapy alone for another six months.
• The study found that the combination of immunotherapy and chemotherapy was effective in reducing cancer recurrence and improving survival rates for patients with dMMR stage 3 colon cancer.
• The researchers recommend this combination of immunotherapy and chemotherapy as the new standard treatment for stage 3 deficient mismatch repair colon cancer.
• The study included patients with Lynch syndrome, the most common form of hereditary colon cancer, as these patients can have tumors that show deficient mismatch repair (dMMR).

Statistics:

• 15% of people diagnosed with colon cancer exhibit dMMR.
• 30% of patients experience cancer recurrence despite standard chemotherapy treatment.
• 712 patients were enrolled in the clinical trial.
• 6 months is the duration of chemotherapy and immunotherapy combination treatment.
• 6 months is the duration of immunotherapy alone treatment.

Sources:

• "New treatment offers hope for patients with deadliest stage of colon cancer" by Tribune Content Agency, LLC (2025)
• The study was presented during a plenary session at the American Society of Clinical Oncology (ASCO) meeting in Chicago.
• Dr. Sinicrope is an oncologist and the lead researcher of the study.