Breakthrough in Colon Cancer Treatment: Immunotherapy and Chemotherapy Combination Shows 50% Reduction in Cancer Recurrence

Researchers at the Mayo Clinic Comprehensive Cancer Center have made a groundbreaking discovery in the treatment of colon cancer. In a study presented at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting, the team found that adding immunotherapy to chemotherapy after surgery for patients with stage 3 (node-positive) colon cancer, specifically those with a genetic makeup called deficient DNA mismatch repair (dMMR), resulted in a 50% reduction in cancer recurrence and death compared to chemotherapy alone. This is a significant advancement in colon cancer treatment, as approximately 15% of people diagnosed with colon cancer exhibit dMMR, and these tumors have been less sensitive to chemotherapy.

Key Takeaways:

• The study involved 712 patients with dMMR stage 3 colon cancer who had undergone surgery and received chemotherapy for six months, followed by immunotherapy for another six months.
• The immunotherapy used was an immune checkpoint inhibitor called atezolizumab, which activates the immune system to attack and kill cancer cells.
• The combination of immunotherapy and chemotherapy 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 this genetic makeup makes tumors less sensitive to chemotherapy.
• The study included patients with Lynch syndrome, the most common form of hereditary colon cancer, who are at a higher risk of developing tumors with dMMR.
• The research team recommends the combination of immunotherapy and chemotherapy as the new standard treatment for stage 3 deficient mismatch repair colon cancer.

Statistics:

• 50% reduction in cancer recurrence and death among patients who received immunotherapy and chemotherapy compared to those who received chemotherapy alone.
• 15% of people diagnosed with colon cancer exhibit dMMR, a genetic make-up that makes tumors less sensitive to chemotherapy.
• 712 patients enrolled in the study, all of whom had undergone surgery and received chemotherapy for six months, followed by immunotherapy for another six months.
• Approximately 30% of patients experience cancer recurrence despite chemotherapy alone.

Sources:

• "Late-breaking abstract presented at ASCO 2025" - VerticalNews
• "Mayo Clinic Comprehensive Cancer Center" - Mayo Clinic
• "American Society of Clinical Oncology (ASCO) Annual Meeting 2025" - ASCO
• National Comprehensive Cancer Network (NCCN)
• NewsRx LLC (2025)