Question special
Lead Moderator

Currently, microsatellite instability is the only molecular factor used in clinical decision-making for the management of colon cancer. Mismatch repair (MMR)-deficiency is more common in stage II tumors as compared to stage III tumors. MMR-deficient tumors are characterized by high frequency microsatellite instability (MSI). MMR-deficiency appears to be both a prognostic biomarker (associated with a lower recurrence risk in patients with stage II colon cancer) and a predictive biomarker (associated with less benefit, or even harm, from adjuvant single agent fluoropyrimidine chemotherapy). In this study, the CDX2-negative, ALCAM-positive subgroup was characterized by only partial overlap with tumors defined by microsatellite instability or TP53 mutations. How does this finding affect our interpretation of CDX2 as a prognostic and predictive marker?