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.
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) (https://doi.org/10.1053/j.gastro.2019.12.031)