The short answer
Lung cancer screening uses low-dose CT scans to look for lung cancer in people at higher risk because of their smoking history. The USPSTF recommends yearly screening for adults 50–80 with a 20 pack-year history who currently smoke or quit within the last 15 years. It reduces lung cancer deaths but has real harms.
Lung cancer screening uses low-dose CT (LDCT), which involves less radiation than a standard CT scan.
It is recommended for people at increased risk because of a significant smoking history, not the general public.
The USPSTF recommends yearly LDCT for adults 50–80 with a 20 pack-year history who currently smoke or quit within 15 years.
NCI reports that the National Lung Screening Trial found three annual LDCT screens reduced lung cancer deaths by 20%.
Watch: Lung cancer screening exists — who qualifies?
52 sec · Captioned · Lung cancer screening exists for people 50-80 with a smoking history.
Educational only — this video explains general report language and is not medical advice. Only your care team can say what a result means for you.
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The full explanation.
The simple version
Lung cancer screening looks for lung cancer before it causes symptoms. It uses a special low-dose CT (LDCT) scan of the lungs. It isn't for everyone. NCI notes that the risk of lung cancer in people who have never smoked is generally so low that they'd be unlikely to benefit. Screening is aimed at people at increased risk because of a significant smoking history.
Who should be screened
The U.S. Preventive Services Task Force recommends annual low-dose CT screening for people who meet all of these:
- Ages 50 to 80.
- A 20 pack-year or more smoking history. That could be one pack a day for 20 years, or two packs a day for 10 years.
- Currently smoke, or quit within the last 15 years.
If you're unsure whether you qualify, your doctor can help you work out your pack-year history and eligibility.
The radiation involved
A low-dose lung CT uses an estimated 1.5 mSv of radiation. That is about the natural background radiation a person receives in six months. It is lower than a typical chest CT, which NCI puts at 6.1 mSv. For people at risk, that small exposure is weighed against the benefit of catching cancer early.
Benefits and harms
The benefit is significant. NCI reports that in the National Lung Screening Trial, three annual low-dose CT screens cut lung cancer mortality by 20%.
But there are real harms to weigh.
- False positives are findings that look abnormal when no cancer is present. They need follow-up, and can lead to invasive procedures to rule out cancer.
- Overdiagnosis means finding a cancer that would never have caused problems. NCI says this does happen with LDCT screening, but it is not clear how often.
- False negatives happen too. A scan can look normal when cancer is there. So a clear result is not a reason to ignore a new symptom.
- Incidental findings come up because the scan also images organs outside the lungs. It may reveal other abnormalities, some serious and many not, that need follow-up.
Don't wait on new symptoms
Screening is for people with no symptoms. It does not replace getting checked when something changes. NCI notes that a screening test can miss a cancer that is there. So check with your doctor promptly if you have a cough that does not go away or gets worse, blood in the mucus you cough up, chest discomfort or pain, trouble breathing, hoarseness, or weight loss for no known reason. Do that even if your last scan was clear. Do not wait for your next yearly scan to raise these.
A word about quitting
Screening does not remove the risk that comes from smoking. It is not a substitute for quitting. If you smoke, the single most powerful thing you can do for your lung health is to stop. Your care team can point you to resources that help. Screening and quitting work best together.
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Words to know
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Common questions
What is lung cancer screening?
Lung cancer screening looks for lung cancer before symptoms appear, using a low-dose CT (LDCT) scan of the lungs. NCI notes that the risk of lung cancer in people who have never smoked is generally so low that they would be unlikely to benefit from screening, so it is aimed at people at increased risk because of their smoking history.
Who should be screened?
The U.S. Preventive Services Task Force recommends annual lung cancer screening with low-dose CT for people ages 50 to 80 who have a 20 pack-year or more smoking history and either currently smoke or quit within the last 15 years. A '20 pack-year' history could mean, for example, one pack a day for 20 years or two packs a day for 10 years.
How much radiation does a low-dose CT use?
The estimated effective dose of a low-dose lung CT is about 1.5 mSv — comparable to roughly 6 months of natural background radiation, and lower than a typical chest CT (6.1 mSv). Your care team weighs this small exposure against the benefit of screening for those at risk.
Does lung cancer screening save lives?
NCI reports that the National Lung Screening Trial found three annual low-dose CT screens reduced lung cancer mortality by 20%. That benefit is why screening is recommended for people at higher risk — but it must be weighed against the potential harms.
What are the harms of lung cancer screening?
People screened with low-dose CT can have false-positive results — findings that look abnormal even though no cancer is present — which need monitoring and may lead to invasive procedures to rule out cancer. Overdiagnosis (finding a cancer that would not have caused problems) is possible. And because the scan also images areas outside the lungs, it can turn up incidental findings, some serious and many not.
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Last updated: 2026-08-18Next planned review: 2027-01-03
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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