Screening & monitoring · graded by use, two uses
Low-dose CT screening for lung cancer in heavy smokers
Lung cancer deaths, current and former heavy smokers aged 50 to 74.
At a glance
This is about yearly low-dose CT scans of the chest for people who smoked heavily. In two large studies, fewer of them died of lung cancer, about 1 in 5 fewer. Most positive scans turned out to be false alarms, which led to more scans and some tests. One study also found fewer deaths from any cause; the other did not report a clear drop.
- What was measured
- Deaths from lung cancer, deaths from any cause and false alarms in current and former heavy smokers given repeated low-dose CT scans of the chest.
- How big
- The full report counts 356 lung cancer deaths among 26,722 people assigned to low-dose CT against 443 among 26,732 assigned to chest X-rays, a 20.0% relative drop. Among people screened at least once, 320 had to be screened with CT to prevent one lung cancer death.Read from the full report 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. 21714641 (PubMed Central PMC4356534).
- Who it applies to
- Current and former heavy smokers: 53,454 people in the US, and men and women aged 50 to 74 in the Netherlands and Belgium, where the result in women was not clear on its own. People who never smoked were not studied.
- Safety
- In the US trial, 24.2% of CT scans were positive and 96.4% of those were false alarms, leading to more scans and some invasive procedures; lung cancer was found more often, partly cancers that would not have caused harm. Each scan carries a small radiation dose.
- Compared with
- A chest X-ray each year in the US trial; no screening in the Dutch and Belgian trial.
- Certainty
- Grade A, resting on: Large randomized trials of low-dose CT screening against chest X-ray or no screening.
- What would change this grade
- Could move down to B if this trial found no benefit: A large population trial of low-dose CT screening against no screening, run by a group independent of NLST and NELSON, or longer follow-up of both trials. Who: Current and former heavy smokers aged 50 to 74, women and men. Measured: Deaths from lung cancer in national registries, with death from any cause. Length: 10 years or more of follow-up.
- Cost
- No price recorded yet.
- Sources
- 3 studies cited on this record, listed under Sources.
The A belongs to one of the two uses graded on this record. The other one carries its own letter.
As studied, and the trials
NLST (N Engl J Med, 2011; PMID 21714641): lung cancer deaths 20.0% lower with low-dose CT than with chest X-ray, 62 fewer per 100,000 person-years. NELSON (de Koning et al., N Engl J Med, 2020; PMID 31995683): lung cancer deaths 24% lower in men at 10 years (rate ratio 0.76, 0.61 to 0.94). Two independent trials, a hard outcome: A.
As studied, and the trials
NLST found deaths from any cause 6.7% lower with CT than with chest X-ray (PMID 21714641). A pooled analysis of screening trials estimated 107 days of lifetime gained, not significant (Bretthauer et al., 2023; PMID 37639247). One significant trial, not repeated: C.
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A letter describes the human evidence, not the product, the manufacturer, or the intervention's worth.
See the full evidence record →Low-dose CT screening for lung cancer in heavy smokers, graded on deaths from lung cancer in current and former heavy smokers: 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 lung cancer deaths in current and former heavy smokers: two independent large trials found them lower, by 20% against chest X-ray in the US (NLST; PMID 21714641) and by 24% against no screening in men in the Netherlands and Belgium, in the NELSON trial (PMID 31995683). 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 groups: A. Grade C on death from any cause: NLST found it 6.7% lower against chest X-ray, and a pooled lifetime analysis was not significant (PMID 37639247).
WHAT THIS GRADE DOES NOT COVERpeople who never smoked or smoked less than the trials required; chest X-ray screening; and women, where NELSON's result was not significant on its own.
Shared endpoint: Lung cancer deaths with low-dose CT screening, current and former heavy smokers
- NLST, 33 US centers (National Lung Screening Trial Research Team): Lung cancer deaths 20.0% lower than with chest X-ray, 53,454 participants. PMID 21714641 · Funding: US National Cancer Institute
- NELSON, the Netherlands and Belgium (de Koning): Lung cancer deaths 24% lower than no screening in men at 10 years, 13,195 men. PMID 31995683 · Funding: not stated in the indexed record
What the replication does not cover: NLST compared CT with chest X-ray, not with no screening. In NELSON the result in 2,594 women was not significant on its own (rate ratio 0.67, 0.38 to 1.14).
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 Low-Dose CT Lung Cancer Screening among studies recruiting now. EBL has no relationship with any listed study and receives no payment for this link.
Search recruiting studies of Low-Dose CT Lung Cancer Screening on ClinicalTrials.gov
Evidence notes: randomized trial, independently replicated
Endpoint graded: Deaths from lung cancer in current and former heavy smokers (hard)
Last reviewed: October 2026
Dose, form and timing
Measured in the trials: deaths from lung cancer and from any cause in national registries, positive and false-positive screens, and lung cancer diagnoses.
Safety
In NLST, 24.2% of low-dose CT screens were positive and 96.4% of those positive results were false, leading to further scans and some invasive procedures; lung cancer was diagnosed 13% more often with CT than with chest X-ray, part of which is cancers that would not have caused harm (PMID 21714641). In NELSON, 9.2% needed at least one extra scan and 2.1% were referred for a suspicious nodule (PMID 31995683). Each scan carries a small radiation dose.
Cautions documented in human studies. Each caution on this record, sorted by what it rests on.
- False positives: in NLST, 24.2% of screens were positive and 96.4% of those were false, leading to more scans and some invasive procedures. (PMID 21714641)
- Overdiagnosis: lung cancer was diagnosed 13% more often with CT than chest X-ray, partly cancers that would not have caused harm. (PMID 21714641)
- In NELSON, 9.2% needed at least one extra scan and 2.1% were referred for a suspicious nodule. (PMID 31995683)
None recorded.
- Radiation: each scan carries a small radiation dose.
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 evidenceThree papers, each linked to its PubMed record.
NLST (National Lung Screening Trial Research Team, N Engl J Med, 2011; PMID 21714641): 53,454 heavy smokers at 33 US centers, three annual low-dose CT scans against chest X-ray; lung cancer deaths 247 against 309 per 100,000 person-years, 20.0% lower (6.8 to 26.7); death from any cause 6.7% lower (1.2 to 13.6); 24.2% of CT screens were positive and 96.4% of positive results were false; lung cancer incidence 13% higher with CT. Funded by the US National Cancer Institute. NELSON (de Koning et al., N Engl J Med, 2020; PMID 31995683): 13,195 men and 2,594 women aged 50 to 74 who smoked or had smoked, in the Netherlands and Belgium, volume CT at baseline and years 1, 3 and 5.5 against no screening; at 10 years lung cancer deaths 2.50 against 3.30 per 1,000 person-years in men (rate ratio 0.76, 0.61 to 0.94), 0.67 (0.38 to 1.14) in women; 2.1% referred for suspicious nodules. Bretthauer et al. (JAMA Intern Med, 2023; PMID 37639247): lifetime gained 107 days (-286 to 430), not significant.
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.
("low-dose computed tomography"[tiab] OR "low-dose CT"[tiab] OR "volume CT"[tiab]) AND lung cancer[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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