Screening & monitoring · graded by use, three uses
Sigmoidoscopy and colonoscopy screening for colorectal cancer
Colorectal cancer deaths, an invitation to flexible sigmoidoscopy, adults aged 55 to 64.
At a glance
This is about looking inside the bowel to find cancer early. In four large studies, people invited to a short scope of the lower bowel were less likely to die of bowel cancer over 15 years. That works out to about 1 death prevented for every 770 people invited. One study of a full colonoscopy found fewer bowel cancers after 10 years. Deaths from bowel cancer were not clearly lower, but only 4 in 10 people invited went.
- What was measured
- Deaths from bowel (colorectal) cancer and new bowel cancers, counted in national registries for everyone invited to a scope of the lower bowel, whether or not they went.
- How big
- After 15 years there were 0.13 fewer deaths from bowel cancer per 100 people invited to the scope than with usual care; the death rate was 0.80 times the usual care rate. The summary gives this per 100 people invited, not the two group rates.Read from the summary of PMID PubMed ID: the permanent number the US National Library of Medicine gives a published paper. Each one links to that paper's record on PubMed. 36215714.
- Who it applies to
- Adults aged 55 to 64 at the start, in Norway, the US, the UK and Italy, invited to one or two scopes of the lower bowel. People with bowel symptoms or a family history of bowel cancer were not the group studied.
- Safety
- Positive screens lead to a full colonoscopy and polyp removal. In the colonoscopy trial, 15 of the 11,843 people screened had major bleeding after polyp removal, with no bowel tears and no deaths within 30 days.
- Compared with
- Usual care, with no invitation to screening.
- Certainty
- Grade A, resting on: Population randomized trials of an invitation to screening against usual care, and their pooled analysis.
- What would change this grade
- Could move down to B if this trial found no benefit: Longer follow-up of the four sigmoidoscopy trials, or a new large population trial of an invitation to flexible sigmoidoscopy against usual care run by a group independent of them, analyzed by intention to screen. Who: Adults aged 55 to 64 at average risk, women and men reported separately. Measured: Deaths from colorectal cancer in national registries. Length: 15 years or more of follow-up.
- Cost
- No price recorded yet.
- Sources
- 7 studies cited on this record, listed under Sources.
The A belongs to one of the three uses graded on this record. The other two carry their own letters.
As studied, and the trials
Juul et al. (Ann Intern Med, 2022; PMID 36215714) pooled the four trials: after 15 years, 0.13 fewer colorectal cancer deaths per 100 people invited (rate ratio 0.80, 0.72 to 0.88), about 1 death prevented for every 770 invited (worked out by EBL from the 0.13 per 100), with less benefit in women than in men. Each trial was run by a different national group: PLCO in the US (PMID 22612596), NORCCAP in Norway (PMID 25117129), UKFSST in the UK (PMID 28236467) and SCORE in Italy (PMID 21852264). A hard outcome replicated The same finding reproduced by a separate research group. A result seen once can be chance or bias; a replicated one is harder to explain away. across independent groups: A.
As studied, and the trials
NordICC (Bretthauer et al., N Engl J Med, 2022; PMID 36214590): colorectal cancer was diagnosed in 0.98% of those invited against 1.20% with usual care at 10 years (risk ratio 0.82, 0.70 to 0.93); 455 people had to be invited to prevent one case. One trial, not yet repeated: C under Rule 06.
As studied, and the trials
NordICC (PMID 36214590): deaths from colorectal cancer were 0.28% against 0.31% (risk ratio 0.90, 0.64 to 1.16) and deaths from any cause 11.03% against 11.04%, neither significantly different at 10 years. A pooled analysis of screening trials estimated 37 days of lifetime gained with colonoscopy, not significant (Bretthauer et al., 2023; PMID 37639247). With fewer than half attending and 10 years of follow-up, the trial may have been too short or too diluted to show a death benefit; that is a reason for the 15-year result, not a reason to grade above D now.
Read the grade that matches your goal. How EBL grades by use →
A letter describes the human evidence, not the product, the manufacturer, or the intervention's worth.
See the full evidence record →Sigmoidoscopy and colonoscopy screening for colorectal cancer, graded on deaths from colorectal cancer after an invitation to sigmoidoscopy screening, adults 55 to 64: what the randomized trials measured, in whom, and what they did not show.
Why this letter
Why this gradeThe reasoning, and what the grade does not cover.
Grade A on deaths from colorectal cancer after an invitation to sigmoidoscopy: four independent population trials, pooled to a 20% reduction at 15 years (PMID 36215714), a hard outcome replicated across groups. Grade C on colorectal cancer diagnoses after an invitation to colonoscopy: one trial, an 18% reduction at 10 years (NordICC; PMID 36214590), not yet repeated (Rule 06). Grade D, tested, on colorectal cancer deaths and on death from any cause after an invitation to colonoscopy: NordICC found neither significantly lower at 10 years (PMID 36214590), with 42% attendance; its 15-year results are not yet published.
WHAT THIS GRADE DOES NOT COVERpeople who attended rather than everyone invited, which the trials report only as adjusted estimates; stool tests, graded on their own record; and people with symptoms or a family history, who were not the population studied.
Shared endpoint: Colorectal cancer deaths after an invitation to flexible sigmoidoscopy against usual care, adults aged 55 to 64
- PLCO, United States (Schoen): Colorectal cancer deaths 26% lower (relative risk The risk in one group expressed as a share of the risk in another. It can make a small absolute difference look large. 0.74), median 11.9 years. PMID 22612596 · Funding: not stated in the indexed record
- NORCCAP, Norway (Holme): Colorectal cancer deaths lower, hazard ratio How often an event happened in the treated group compared with the control group over the same period. A ratio of 0.80 means 20 percent fewer events. 0.73, median 10.9 years. PMID 25117129 · Funding: not stated in the indexed record
- UKFSST, United Kingdom (Atkin): Colorectal cancer deaths lower with protection lasting at least 17 years. PMID 28236467 · Funding: not stated in the indexed record
What the replication does not cover: Attendance was 58% to 84%. The Italian trial (PMID 21852264) found deaths 22% lower, not significant by intention to screen. Women benefited less than men in the pooled analysis.
A grade describes the human evidence for a named use. It is not advice, and it is not a judgment on any individual prescription. How the letters are decided →
ClinicalTrials.gov, the public registry run by the U.S. National Library of Medicine, lists studies that are recruiting volunteers. The link below searches it for Colonoscopy Screening among studies recruiting now. EBL has no relationship with any listed study and receives no payment for this link.
Search recruiting studies of Colonoscopy Screening on ClinicalTrials.gov
Evidence notes: randomized trial, independently replicated, meta-analysis A study that pools the numbers from several trials into one combined estimate.
Endpoint graded: Deaths from colorectal cancer after an invitation to sigmoidoscopy screening, adults 55 to 64 (hard)
Last reviewed: October 2026
Dose, form and timing
Measured in the trials: colorectal cancer diagnoses and deaths from colorectal cancer in national registries, counted for everyone invited, whether or not they attended.
Safety
In NordICC, 15 of the 11,843 people screened by colonoscopy had major bleeding after polyp removal; there were no perforations and no deaths within 30 days (PMID 36214590). Positive screens lead to further colonoscopy and polyp removal.
Cautions documented in human studies. Each caution on this record, sorted by what it rests on.
- In NordICC, 15 of 11,843 people screened by colonoscopy had major bleeding after polyp removal, with no perforations and no deaths within 30 days. (PMID 36214590)
None recorded.
None recorded.
None recorded.
Does not apply: human harm data are listed above.
Sources
- Citations
- Every paper cited on this page is matched to its PubMed record on every build.
- Retractions
- None of these papers is retracted or under a journal expression of concern. PubMed is checked again on every build.
- Read against the papers
- October 2026. By the EBL editor, Arnold Sandlow, DC.
- Outside review
- Not yet done. No reviewer outside EBL has checked this record.
What each of these checks can and cannot show: evidence integrity.
Primary evidenceSeven papers, each linked to its PubMed record.
Sigmoidoscopy: Juul et al. (Ann Intern Med, 2022; PMID 36215714) pooled 4 randomized trials, 274,952 adults aged 55 to 64 in Norway, the US, the UK and Italy; after 15 years colorectal cancer deaths were 20% lower (rate ratio 0.80, 0.72 to 0.88), 0.13 fewer deaths per 100 people invited, and cases 21% lower; women benefited less than men. The trials: PLCO (Schoen et al., N Engl J Med, 2012; PMID 22612596), deaths 26% lower; NORCCAP (Holme et al., JAMA, 2014; PMID 25117129), hazard ratio 0.73; UKFSST (Atkin et al., Lancet, 2017; PMID 28236467), protection lasting at least 17 years; SCORE (Segnan et al., J Natl Cancer Inst, 2011; PMID 21852264), deaths 22% lower, not significant by intention to screen. Colonoscopy: NordICC (Bretthauer et al., N Engl J Med, 2022; PMID 36214590), 84,585 adults aged 55 to 64 in Poland, Norway and Sweden, one invitation to colonoscopy against usual care, 42.0% of those invited attended; at 10 years colorectal cancer was diagnosed in 0.98% against 1.20% (risk ratio 0.82, 0.70 to 0.93) and deaths from it were 0.28% against 0.31% (0.90, 0.64 to 1.16); death from any cause 11.03% against 11.04%. Lifetime: Bretthauer et al. (JAMA Intern Med, 2023; PMID 37639247) pooled randomized screening trials with more than 9 years of follow-up and found sigmoidoscopy the only test with a significant gain in lifetime, 110 days (0 to 274), and colonoscopy 37 days (-146 to 146). NordICC was funded by the Research Council of Norway and others.
Evidence Based Longevity, Inc. is owner-operated and edited by Arnold Sandlow, D.C., a California-licensed chiropractor. Evidence Based Longevity publishes in English only · Machine translations are not produced or reviewed by EBL for accuracy
How EBL searched for the trials (1 search)
The search that was run, what it returned, and what was left out and why, so the absence of evidence can be checked as well as its presence.
(sigmoidoscopy[ti] OR colonoscopy[ti]) AND screening[ti] AND randomized controlled trial[pt] AND mortality[tiab]PubMed watch: does a new study change the grade? (nothing new)
No new paper matching the search behind this grade has been added to PubMed since October 2026.
Last run October 2026. A letter on EBL moves only after a logged review. A new paper never moves a letter by arriving: it is read, the answer is written here, and any change to the letter is published in the evidence log.
Disclosure
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