MSI testing in Stage II colon cancer: are we ready for prime time?

Amil Shah, MDCM, FRCPC, FACP

For Stage II colon cancer, in which the majority of patients are cured by surgical resection, the role of adjuvant chemotherapy is uncertain. Some subgroups of Stage II patients are recognized to be at high risk for recurrence and may be potential candidates for adjuvant therapy. High-risk factors include tumour characteristics (adherence to adjacent tissues, perforation or complete obstruction), biologic characteristics (aneuploidy or deletion of 18q) and treatment-related characteristics (inadequate lymph node sampling). In 2004 the Gastrointestinal Cancer Disease Site group of Cancer Care Ontario’s Program in Evidence-Based Care published a meta-analysis of randomized studies of adjuvant chemotherapy compared with observation for Stage II colon cancer.