FDA approved atezolizumab with chemotherapy for adjuvant treatment of stage III dMMR colon cancer following results from the phase III ATOMIC trial. The study reported a 50% reduction in the risk of recurrence or death versus the control approach. The decision adds another immunotherapy-backed option to the stage III treatment landscape, particularly for a biomarker-defined subgroup where recurrence risk can be substantial despite standard regimens. Clinicians and payers will now focus on real-world adoption questions—sequencing, combination tolerability, and the extent to which outcomes match trial results across practice settings.