- Adjuvant chemotherapy is associated with improved outcomes in proficient mismatch repair (pMMR) status stage II colon cancer tumors, but not in defective mismatch repair (dMMR) tumors.
Why this matters
- Adjuvant chemotherapy is generally reserved for "high-risk" patients with stage II colon cancer, but no firm data show that the markers for this diagnosis are reliably predictive.
- Retrospective, multicenter study (N=451; dMMR, 92; pMMR, 359).
- Funding: None disclosed.
- Median follow-up, 73 (79.1 pMMR vs 67.6 dMMR; P=.004) months.
- Adjuvant treatment was not associated with a survival benefit in patients with dMMR tumors (HR, 1.05; P=.897).
- In a multivariable model, adjuvant treatment was associated with better OS in patients with pMMR tumors (HR, 0.42; P=.007).
- Among patients who relapsed, postrelapse survival was not significantly different with respect to postoperative management in the dMMR group, but pMMR patients who were treated with adjuvant chemotherapy had a longer postrelapse survival (HR, 0.55; P=.033).
- Retrospective analysis.