# National Polyp Study

Source: https://onco.cc/trials/national-polyp-study/  
OnCo record `national-polyp-study` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

The study that showed removing a polyp at colonoscopy does not just prevent cancer, it prevents death from it: half as many deaths as expected, fifteen years on.

## Summary

The National Polyp Study followed 2,602 patients whose adenomas had been removed at colonoscopy. After a median 15.8 years, 1,246 had died of any cause and 12 of colorectal cancer, against 25.4 deaths expected from Surveillance, Epidemiology and End Results rates: a standardised incidence-based mortality ratio of 0.47 (95% CI 0.26 to 0.80), a 53 percent reduction. Mortality from colorectal cancer in the first ten years after polypectomy was the same as in the internal control group of people with non-adenomatous polyps. The study is the evidence that the adenoma-carcinoma sequence can be interrupted mechanically, which is the whole basis of colonoscopic screening and of the surveillance intervals that follow polypectomy.

## Fields

- Kind: Trial
- Status: positive
- Last checked: 2026-09-24
- Also known as: NPS
- Phase: observational
- Setting: People whose adenomas were removed at colonoscopy: long-term colorectal cancer mortality against the general population and against people with non-adenomatous polyps
- Sponsor: National Cancer Institute (US)
- Enrolled: 2602
- Result: Standardised incidence-based mortality ratio 0.47 (95% CI 0.26 to 0.80) after polypectomy, a 53 percent reduction in deaths from colorectal cancer.
- Outcomes: Colorectal cancer mortality against the general population: After colonoscopic polypectomy 0.47 standardised mortality ratio
- Replication: NordICC, the first randomised trial of invitation to colonoscopy, found a smaller effect in intention-to-treat analysis because only 42 percent of those invited attended.

## Sources

- National Polyp Study: colonoscopic polypectomy and long-term prevention of colorectal cancer deaths (New England Journal of Medicine 2012): https://doi.org/10.1056/NEJMoa1100370

## Connected records

- cancers: [Colorectal cancer](https://onco.cc/cancers/colorectal/)
- fronts: [Early Detection & Screening](https://onco.cc/fronts/early-detection/), [Prevention & Risk](https://onco.cc/fronts/prevention/)
- technologies: [Colorectal cancer screening (colonoscopy, FIT, stool DNA, blood)](https://onco.cc/technologies/colorectal-screening/), [Endoscopic resection (EMR / ESD)](https://onco.cc/technologies/endoscopic-resection/)
- trials: [Minnesota Colon Cancer Control Study](https://onco.cc/trials/minnesota-fob/), [NordICC (Nordic-European Initiative on Colorectal Cancer)](https://onco.cc/trials/nordicc/)

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