Prognostic Features and Potential for Immune Therapy in Metastatic Mismatch Repair-Deficient Colorectal Cancer: A Retrospective Analysis of a Large Consecutive Population-Based Patient Series

Abstract

Some colorectal cancers carry a DNA repair defect — called mismatch repair — making them unusually responsive to immunotherapy. Studying all such tumors in a large Finnish population over 15 years, researchers found that despite a favorable immune environment, most patients with metastatic disease were too elderly or frail to receive treatment, and many tumors showed features likely to limit immunotherapy benefit. The findings reveal a significant gap between these cancers’ theoretical treatability and what is achievable in real-world care.