Missed colorectal cancer diagnosis by screening colonoscopy based on the PLCO cancer screening trial.

[PURPOSE] This study aimed to evaluate the proportion of colorectal cancer (CRC) missed by colonoscopy and the characteristics of the patients with missed diagnosis using data from the prostate, lung, colorectal, and ovarian (PLCO) cancer screening trial, and to analyze and compare patient survival between detection and missed diagnosis groups for an evidence-based basis for improving the effectiveness of colorectal cancer screening.

[PATIENTS AND METHODS] Patients with CRC identified by baseline or follow-up colonoscopy and those identified by annual study update questionnaires or National Death Index search, without any positive findings by colonoscopy in the screening arm of the PLCO study, were included in this study. We calculated the rate of missed CRC diagnosis by colonoscopy using the definition of missed cases as the numerator and the sum of patients with CRC as the denominator.

[RESULTS] Three hundred sixty patients with CRC were included in the final analysis (detection group, n = 298; missed diagnosis group, n = 62). The overall rate of missed CRC diagnosis by colonoscopy was 17.22%. Patients with a history of colorectal polyps had a higher rate of missed diagnoses (33.3%). The missed diagnosis rate was higher in patients with proximal CRC (31.3%). CRC occurring in the transverse colon (29.6%), hepatic flexure of the colon (40.0%), ascending colon (27.0%), and cecum (36.6%) were more likely to be missed by colonoscopy. The later the stage, the higher the missed CRC diagnosis rate (10.5, 20.0, 30.8, and 30.8% for stages I-IV, respectively).

[CONCLUSION] Colonoscopy missed a relatively high proportion of CRC, mainly in the proximal colon (especially in the hepatic flexure and cecum of the colon). Recent developments in non-invasive screening technologies, such as stool DNA testing and liquid biopsy, may help address the limitations of colonoscopy. Combining these approaches with traditional endoscopy could enhance overall detection accuracy and reduce the rate of missed colorectal cancer.