Variation in the detection of both adenomas and cancers at colonoscopy is well established, and adenoma detection is a valid indicator of the quality of colonoscopy. A study reported in this issue demonstrated variable detection of serrated lesions among endoscopists. It is possible that serrated lesions are a major key to the lower level of protection provided by colonoscopy for proximal compared with the distal colon cancer, and serrated lesions may be an appropriate detection target during colonoscopy.