ObjectiveTo explore whether the regular feedback system in opportunistic screening of colorectal cancer can improve the adenoma detection rate (ADR) of endoscopists. MethodsThis study was an observational study, divided into three stages: the baseline stage before intervention (the pre-intervention period), the regular feedback stage (the intervention period) and the post-intervention stage (the post-intervention period). In the pre-intervention period, all patients who underwent opportunistic screening of colorectal cancer in Department of Gastroenterology in Beijing Shijitan Hospital Affiliated to Capital Medical University from June 2017 to May 2018 were reviewed, and the ADR of each endoscopist was calculated. In the intervention period from June 2018 to November 2018, colonoscopies were performed on patients for opportunistic screening of colorectal cancer by endoscopists who participated in the feedback. The ADR of each endoscopist during the previous month was calculated at the beginning of each month and feedback was provided in the form of a report. In the post-intervention period from December 2018 to January 2019, colonoscopies were performed on patients for opportunistic screening of colorectal cancer by endoscopists who participated in the feedback. The ADR of each endoscopist was calculated after the feedback stopped. ADR and polyp detection rate (PDR） of three stages were compared. ResultsA total of 1 768, 1 308 and 344 patients were enrolled for opportunistic screening of colorectal cancer during the pre-intervention, the intervention and the post-intervention period respectively. Eight endoscopists participated in the whole process of this study. The total ADR increased from 23.70% (419/1 768) in the pre-intervention period to 33.72% (441/1 308) in the intervention period (χ2=37.449, P＜0.05). Two months after intervention, ADR decreased slightly to 33.14% (114/344), but was still higher compared with before (χ2=13.602, P＜0.05). The total PDR increased from 47.17% （834/1 768） in the pre-intervention period to 52.68% （689/1 308） in the intervention period (χ2=9.111，P<0.05).Two months after the intervention, PDR increased slightly to 53.78% (185/344), and still higher compared with before (χ2=5.035, P＜0.05). ConclusionRegular feedback to endoscopists can improve ADR in opportunistic screening of colorectal cancer.