Adjuvant Chemotherapy Should Not Routinely Be Recommended to Patients with Stage II Colon Cancers that Manifest Microsatellite Instability

摘要

Patients with stage II colorectal cancer (CRC) generally appear to benefit modestly from adjuvant chemotherapy after surgery. A subset of patients with stage II disease with higher recurrence risk (T4 tumor, poorly differentiated histology, lymphovascular invasion, bowel obstruction, < 12 lymph nodes examined, perineural invasion, perforation, positive margins) do appear to benefit manifesting a 7% increase in 3-year disease-free survival (DFS) when given adjuvant FOLFOX as compared to 5-FU alone. Microsatellite instability (MSI) manifested by missing mismatch repair (dMMR) proteins is a biologic footprint for impaired DNA repair noted in approximately 15% to 20% of CRCs. This article argues that adjuvant therapy in the subset of patients with stage II MSI CRC lacks benefit and should not be administered.