Is the ColDx assay a valid prognostic marker for stage II colon cancer?

In the United States, colorectal cancer is the fourth most prevalent neoplasm and the second most frequent cause of cancer-related death (1). Surgery alone is standard-of-care for stage I cancer, whereas adjuvant chemotherapy is recommended for stage III. Surprisingly, despite its prevalence, the most appropriate management for stage II colon cancer remains uncertain. Currently-accepted guidelines recommend adjuvant chemotherapy for those considered ‘high-risk’ for recurrence, defined as stage T4 cancer, poorly-differentiated histology, inadequate lymph node sampling, positive or unknown margins, lympho-vascular or perineural invasion, bowel obstruction, or perforation (2).