“While most studies have found that patients with dMMR (vs proficient MMR [pMMR]) tumors have a more favorable stage-adjusted prognosis, other studies have not detected a significant difference in clinical outcome or have suggested that any favorable prognostic effect of dMMR is limited to patients with earlier-stage tumors. Furthermore, studies have shown that dMMR tumors may not benefit from fluorouracil-based adjuvant chemotherapy. However, the impact of MMR status remains controversial in the era of the standard FOLFOX adjuvant chemotherapy.
In a pooled analysis, we examined the association of MMR status with disease-free survival (DFS) in patients with stage III colon cancer treated with FOLFOX from 2 phase 3 randomized clinical trials.”

“In the present pooled analysis of patients with stage III colon cancer treated with FOLFOX in 2 adjuvant trials, we found that the dMMR phenotype was a favorable prognostic factor. Although the Harrell c index is of marginal clinical utility (<0.70), our study has several strengths that include prospective tissue biospecimen collection and uniform tumor stage (III only) and treatment of patients enrolled in large recent randomized studies. Our report represents the largest study to date evaluating the relationship of MMR status with clinical outcome for FOLFOX adjuvant treatment.”

Zaanan, A., et al (2018). Role of Deficient DNA Mismatch Repair Status in Patients With Stage III Colon Cancer Treated With FOLFOX Adjuvant Chemotherapy: A Pooled Analysis From 2 Randomized Clinical Trials. JAMA oncology, 4(3), 379–383.