Lung cancer kills more people worldwide than any other cancer. It's also one of the few cancers where a screening tool has been proven, in large randomized trials, to reduce mortality. That tool is low-dose computed tomography — LDCT. And yet most people who qualify for it have never been offered the test.

The evidence: two landmark trials

The case for LDCT screening rests on two major studies that together enrolled nearly 70,000 participants.

The National Lung Screening Trial (NLST), published in 2011, compared annual LDCT to chest X-ray in over 53,000 current and former heavy smokers aged 55–74. The result: a 20% reduction in lung cancer mortality in the LDCT group. This was one of the clearest screening benefits ever demonstrated in oncology.

The NELSON trial, published in 2020, confirmed these findings in a European population of over 15,000 participants. Among men, lung cancer mortality was reduced by 24% at 10 years. Among women the estimate was even larger — 33% — but it rested on far fewer participants (about 2,600) and was not statistically significant at 10 years.

20%Mortality reduction (NLST)
24%Mortality reduction, men (NELSON)
320NNS over 6.5 years

Who should get screened

LDCT screening is not for everyone. The evidence supports screening in a specific high-risk population. In the US, the USPSTF (2021) recommends annual screening for people who meet all of the following:

  • Age 50–80
  • 20+ pack-year smoking history (pack-years = packs per day × years smoked)
  • Current smoker or quit within the last 15 years

Criteria differ by country. In Germany, statutory health insurance has covered annual LDCT screening since April 2026 for people aged 50–75 who have smoked for at least 25 years with at least 15 pack-years, and who still smoke or quit less than 10 years ago.

Outside this population, the harms of screening — false positives, unnecessary biopsies, radiation exposure, anxiety — outweigh the benefits. This is exactly the kind of risk stratification that evidence-based preventive medicine requires.

What "low-dose" actually means

A standard diagnostic chest CT delivers roughly 7 millisieverts (mSv) of radiation. A low-dose CT delivered about 1.5 mSv on average in the NLST — roughly a fifth of that. The "low-dose" part matters because it makes annual screening feasible without accumulating meaningful radiation risk over time.

The scan takes about 15 seconds. No injection, no preparation, no sedation. You lie down, hold your breath briefly, and it's done.

The false-positive problem

LDCT screening has a significant false-positive rate, and this deserves honest discussion. In the NLST, about 24% of LDCT scans found something abnormal. Of those, 96% turned out to be benign — mostly small lung nodules that needed follow-up imaging but ultimately meant nothing.

Because screening is repeated, the chance per person adds up: over three annual rounds, about 39% of NLST participants had at least one positive scan that caused anxiety and required additional imaging. A small number will undergo biopsies for lesions that turn out to be harmless. This is a real harm, and anyone offering LDCT screening has a responsibility to discuss it openly before the scan.

A reasonable approach

Good practice limits LDCT to people who meet the evidence-based criteria (in the US 20+ pack-years and age 50–80; national criteria differ) and discusses the false-positive rate explicitly before any scan. If you don't meet the criteria, a scan is generally not advisable — outside the high-risk population, the harms outweigh the benefits.

Why this matters for US patients specifically

LDCT lung screening has been recommended by the USPSTF since 2013 and is covered by Medicare and most private insurance. Despite this, uptake in the US remains shockingly low — in 2022, only about 16% of eligible Americans had been screened. The reasons are systemic: many physicians don't bring it up, many patients don't know they qualify, and the process of scheduling and following up is fragmented.

What this means for you

Because eligibility is rarely checked automatically, it often falls to the patient to raise it. If your age and smoking history put you in the qualifying range — including if you quit within the last 15 years (in Germany: within the last 10 years) — it is worth asking your doctor directly about LDCT screening. Useful questions include:

  • Do I meet the criteria for lung cancer screening, based on my pack-years and when I quit?
  • Where is the scan done, and how are nodules followed up?
  • What happens if something is found — who coordinates the next steps?

References

  1. National Lung Screening Trial Research Team. Reduced lung-cancer mortality with low-dose computed tomographic screening. N Engl J Med. 2011;365:395-409.
  2. de Koning HJ, et al. Reduced lung-cancer mortality with volume CT screening in a randomized trial (NELSON). N Engl J Med. 2020;382:503-513.
  3. US Preventive Services Task Force (Krist AH, et al.). Screening for lung cancer: US Preventive Services Task Force recommendation statement. JAMA. 2021;325(10):962-970.
  4. Henderson LM, et al. Prevalence of lung cancer screening in the US, 2022. JAMA Netw Open. 2024;7(3):e243190. doi:10.1001/jamanetworkopen.2024.3190.
  5. Gemeinsamer Bundesausschuss (G-BA). Lungenkrebs-Früherkennung mittels Niedrigdosis-CT: Beschluss zur Krebsfrüherkennungs-Richtlinie. Pressemitteilung, 2025.
Prof. Dr. med. Markus Guba

Head of Liver Surgery and Transplantation at LMU University Hospital Munich. Edits this independent journal in a private capacity; views are his own. About →

This article is general information and not individual medical advice. Decisions about tests and treatment belong in a conversation with your own physician.