# Colonoscopy

Source: https://onco.cc/terms/colonoscopy/  
OnCo record `colonoscopy` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Examining the whole large bowel with a flexible camera; polyps found on the way are removed (polypectomy), which prevents most bowel cancers.

## Summary

The only screening test that both detects and prevents cancer: removing adenomas cuts colorectal cancer incidence and mortality by half or more (National Polyp Study, NordICC). It is the confirmatory test after a positive stool test (FIT) or blood test, and the surveillance tool after polyp removal or resection. Quality is measured by adenoma detection rate and caecal intubation; AI polyp detection raises the former. Bowel preparation and sedation are the main deterrents to uptake.

## Fields

- Kind: Term
- Last checked: 2026-09-09
- Also known as: colonoscopies; colonoscopic; polypectomy; sigmoidoscopy

## Notes

- Bowel cancer and Lynch syndrome: Bowel Cancer UK says people with Lynch syndrome should be in a surveillance programme with regular colonoscopy every 18 months to two years, which can reduce the chance of dying from bowel cancer by as much as 72 percent, and that waits for these routine appointments are often too long.
- The randomised evidence. NordICC, the first randomised trial of screening colonoscopy, invited 28,220 people aged 55 to 64 and compared them with 56,365 receiving usual care: the 10-year risk of colorectal cancer was 0.98 against 1.20 percent, an 18 percent reduction, with 455 invitations needed to prevent one cancer and only 42 percent of invitees attending (Bretthauer 2022). In the National Polyp Study, colorectal cancer mortality among 2,602 patients whose adenomas were removed was 53 percent lower than the general population would predict at a median of 15.8 years (Zauber 2012).
- The interval after polypectomy is set by what was found: in the UK, a one-off surveillance colonoscopy at three years for two or more premalignant polyps including at least one advanced polyp, or five or more premalignant polyps, and otherwise a return to screening (Rutter 2020).

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Colonoscopy
- Wikipedia: https://en.wikipedia.org/wiki/Colonoscopy
- Bowel Cancer UK: Lynch syndrome: https://www.bowelcanceruk.org.uk/campaigning/never-too-young/lynch-syndrome/
- NHS: bowel cancer, tests and next steps: https://www.nhs.uk/conditions/bowel-cancer/tests-and-next-steps/
- Bretthauer, N Engl J Med 2022: NordICC, effect of colonoscopy screening on risks of colorectal cancer and related death (84,585 people): https://doi.org/10.1056/nejmoa2208375
- Rutter, Gut 2020: BSG, ACPGBI and Public Health England post-polypectomy and post-resection surveillance guidelines: https://doi.org/10.1136/gutjnl-2019-319858
- Zauber, N Engl J Med 2012: colonoscopic polypectomy and long-term prevention of colorectal cancer deaths (National Polyp Study, 2,602 patients): https://doi.org/10.1056/nejmoa1100370

## Connected records

- technologies: [Capsule endoscopy (PillCam, EndoCapsule, CapsoCam)](https://onco.cc/technologies/capsule-endoscopy-systems/), [Endoscopic resection (EMR / ESD)](https://onco.cc/technologies/endoscopic-resection/)
- terms: [Adenoma detection rate](https://onco.cc/terms/adenoma-detection-rate/), [Adenoma-carcinoma sequence](https://onco.cc/terms/adenoma-carcinoma-sequence/), [Bowel cancer after abdominal and pelvic radiotherapy](https://onco.cc/terms/second-primary-bowel-after-abdominal-radiotherapy/), [Dysplasia (pre-cancerous change)](https://onco.cc/terms/dysplasia/), [EMR and ESD (endoscopic mucosal resection, endoscopic submucosal dissection)](https://onco.cc/terms/endoscopic-resection-term/), [Endoscopy (EGD, EUS, ERCP)](https://onco.cc/terms/endoscopy/), [Interval cancer](https://onco.cc/terms/interval-cancer/), [Lynch syndrome testing after bowel cancer, and what it means for the family](https://onco.cc/terms/lynch-syndrome-testing-uk/), [NHS bowel cancer screening programme](https://onco.cc/terms/bowel-cancer-screening-uk/), [Polyp types in the bowel](https://onco.cc/terms/colorectal-polyp-types/), [Screening survivors: where the UK, American and European answers differ](https://onco.cc/terms/rejuv-second-screening-after-treatment-compared/), [Screening uptake](https://onco.cc/terms/screening-uptake/), [Serrated pathway](https://onco.cc/terms/serrated-pathway/), [Surveillance intervals after polypectomy](https://onco.cc/terms/colonoscopy-surveillance-intervals/)
- cancers: [Adenoma-like adenocarcinoma of the colon and rectum](https://onco.cc/cancers/colorectal-adenoma-like-adenocarcinoma/), [Colorectal cancer](https://onco.cc/cancers/colorectal/), [Early-onset colorectal cancer (under 50)](https://onco.cc/cancers/early-onset-colorectal/), [Familial adenomatous polyposis-associated colorectal cancer](https://onco.cc/cancers/fap-associated-colorectal-cancer/), [Lynch syndrome-associated colorectal cancer](https://onco.cc/cancers/lynch-associated-colorectal-cancer/)
- fronts: [Early Detection & Screening](https://onco.cc/fronts/early-detection/)
- trials: [UK Flexible Sigmoidoscopy Screening Trial](https://onco.cc/trials/ukfss/)
- key papers: [Colonoscopic polypectomy and long-term prevention of colorectal-cancer deaths (National Polyp Study)](https://onco.cc/key-papers/paper-zauber-national-polyp-study-colonoscopic-polypectomy-nejm-2012/), [NordICC: inviting people to a screening colonoscopy reduced bowel cancer, but less than expected](https://onco.cc/key-papers/paper-nordicc-nejm-2022/), [Quality indicators for colonoscopy and the risk of interval cancer](https://onco.cc/key-papers/paper-kaminski-adenoma-detection-rate-interval-cancer-nejm-2010/), [Terminology, molecular features, epidemiology, and management of serrated colorectal neoplasia](https://onco.cc/key-papers/paper-crockett-nagtegaal-serrated-neoplasia-gastroenterology-2019/), [The serrated pathway to colorectal carcinoma: current concepts and challenges](https://onco.cc/key-papers/paper-bettington-serrated-pathway-colorectal-histopathology-2013/)
- roadmaps: [Colorectal cancer roadmap: from the adenoma-carcinoma sequence and the first screening trials to total mesorectal excision, oxaliplatin, RAS testing, immunotherapy for mismatch repair-deficient disease, ctDNA-guided treatment and organ preservation](https://onco.cc/roadmaps/colorectal-roadmap/)
- ideas: [Treat screening uptake, not test sensitivity, as the thing to optimise, and settle the age extension with a trial rather than a model](https://onco.cc/ideas/idea-crc-screening-uptake-and-age-extension/), [UK gap: match endoscopy capacity and quality to the faecal immunochemical test thresholds the NHS has already set](https://onco.cc/ideas/idea-crc-uk-colonoscopy-capacity-and-fit-threshold/), [UK gap: shorten the route to diagnosis for patients below the screening age, where the rise in incidence is](https://onco.cc/ideas/idea-crc-uk-young-patient-referral-and-diagnostic-interval/)

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