LAUSR

The risk of recurrence from stage II colon cancer and benefit from adjuvant chemotherapy is influenced significantly by the molecular marker termed microsatellite instability and/or mismatch repair (MMR) gene product expression.1 Study results and the National Comprehensive Cancer Network Colon Cancer Guideline panel suggest that adjuvant chemotherapy (fluoropyrimidine [5-FU] +/- oxaliplatin) be considered for patients with stage II colon adenocarcinoma harboring one or more "high-risk" features.2 However, for patients with deficient-MMR (dMMR) stage II colon cancer, evidence suggests there may be a detrimental effect with adjuvant 5-FU alone.3 Finally, the addition of oxaliplatin to 5-FU does not appear to benefit older patients with stage II colon cancer.4,5 For the patient described, the challenge involved how to advise an older patient with a dMMR stage II colon cancer and a high-risk feature. The identified lymphovascular invasion in the tumor implies that adjuvant chemotherapy with either 5-FU or capecitabine +/- oxaliplatin would be reasonable considerations. However, the dMMR status of the tumor suggests that 5-FU alone would be contraindicated, and her age suggests that a lack of benefit would be expected from oxaliplatin.