Colorectal cancer surveillance: what's new and what's next.

The accumulated evidence from two decades of randomized controlled trials has not yet resolved the question of how best to monitor colorectal cancer (CRC) survivors for early detection of recurrent and metachronous disease or even whether doing so has its intended effect. A new wave of trial data in the coming years and an evolving knowledge of relevant biomarkers may bring us closer to understanding what surveillance strategies are most effective for a given subset of patients. To best apply these insights, a number of important research questions need to be addressed, and new decision making tools must be developed. In this review, we summarize available randomized controlled trial evidence comparing alternative surveillance testing strategies, describe ongoing trials in the area, and compare professional society recommendations for surveillance. In addition, we discuss innovations relevant to CRC surveillance and outline a research agenda which will inform a more risk-stratified and personalized approach to follow-up.