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Cancer After Colonoscopy in UK Study Associated With, Well, Some Very Poor-Quality Colonoscopy

Douglas K. Rex, MD, MASGE reviewing Anderson R, et al. Gastroenterology 2020 Jan 8.

Interval cancer, or postcolonoscopy cancer, is one of the dreaded outcomes following colonoscopy. Much of the quality movement in colonoscopy has been directed to preventing this outcome. This study is a review of 107 interval cancers at a single medical center in England, involving 61,110 colonoscopies over an 11-year period with a 3-year interval cancer rate of 4.7%.

There were 30 patients (28%) with prior colorectal cancer (CRC) resections; 4 of these patients had familial adenomatous polyposis or Lynch syndrome and 9 had IBD. Only 5 patients had multiple polyps on previous examinations. 

Using the World Endoscopy Organization scheme for attributing cause, 27% of interval cancers were categorized as possible missed lesions with an adequate prior examination, 58% as possible missed lesions with an inadequate prior examination, 8% as a lesion that was detected but not resected, and 7% as a probable incomplete resection of an identified lesion.

Some interesting features: 

  • Only 31.4% of patients with proximal colon cancers had index examinations that were complete with adequate photo documentation.
  • Only 10% of patients had examinations that were complete with adequate photo documentation, rectal retroflexion, and good bowel preparation. 
  • Rectal retroflexion was documented by either language or photography in only 15% of cases.
  • Only 1 in 9 patients with IBD had chromoendoscopy, and only 1 had segmental biopsies.
  • There were 18 cases in which follow-up procedures were delayed or not booked by administrative staff. 
  • There were 29 cases in which extra-procedural decisions by the endoscopist, such as not repeating a colonoscopy following an exam with an inadequate bowel preparation, contributed to development of postcolonoscopy CRC.


If you are sued for negligence in an interval cancer case, this paper is a listing of stuff you don’t want to find in the patient chart. There are very significant quality issues here in a large fraction of postcolonoscopy cancer cases. This study is a strong argument for sticking to basic quality principles in every single colonoscopy.
Note to readers: At the time we reviewed this paper, its publisher noted that it was not in final form and that subsequent changes might be made.

Douglas K. Rex, MD, MASGE

Bio and Disclosures


Anderson R, Burr NE, Valori R. Causes of post-colonoscopy colorectal cancers based on World Endoscopy Organization system of analysis. Gastroenterology 2020 Jan 8. (Epub ahead of print) (