Clinical practice with respect to metastatic colorectal cancer differs from the other two most common cancers,breast and lung,in that routine surveillance is recommended with the specific intent of detecting liver and lung metastases and undertaking liver and lung resections for their removal.We trace the history of this approach to colorectal cancer by reviewing evidence for effectiveness from the 1950s to the present day.Our sources included published citation network analyses,the documented proposal for randomised trials,large systematic reviews,and meta-analysis of observational studies.The present consensus position has been adopted on the basis of a large number of observational studies but the randomised trials proposed in the 1980s and 1990s were either not done,or having been done,were not reported.Clinical opinion is the mainstay of current practice but in the absence of randomised trials there remains a possibility of selection bias.Randomised controlled trials(RCTs)are now routine before adoption of a new practice but RCTs are harder to run in evaluation of already established practice.One such trial is recruiting and shows that controlled trial are possible. Clinical practice with respect to metastatic colorectal cancer differs from the other two most common cancers, breast and lung, in that routine surveillance is recommended with the specific intent of detecting liver and lung metastases and undertaking liver and lung resections for their removal. We trace the history of this approach to colorectal cancer by reviewing evidence for effectiveness from the 1950s to the present day. Our sources included published citation network analyzes, the documented proposal for randomized trials, large systematic reviews, and meta-analysis of observational studies. position has been adopted on the basis of a large number of observational studies but the randomized trials proposed in the 1980s and 1990s were either not done, or having been done, were not reported. Clinical opinion is the mainstay of current practice but in the absence of randomized trials there remains a possibility of selection bias. Random controlled trials (RCTs) are now routine before adoption of a new practice but RCTs are harder to run in evaluation of already established practice. One such trial is recruiting and shows that controlled trial are possible.