A widespread assumption keeps people out of lung cancer screening rooms: that quitting cigarettes ends the need for a scan. The federal guideline says otherwise. Eligibility continues for 15 full years after a person's last cigarette, and roughly four out of five adults who qualify are not getting screened.
The U.S. Preventive Services Task Force recommends annual screening with low-dose computed tomography for adults aged 50 to 80 who have at least a 20-pack-year smoking history and who either currently smoke or quit within the past 15 years. A pack-year is the equivalent of smoking one pack a day for a year, so 20 pack-years could be one pack daily for two decades or two packs daily for a decade.
The practical consequence is that a 58-year-old who smoked a pack a day through their thirties and quit at 50 still qualifies today. Many such adults believe they aged out of the risk the day they stopped.
The Uptake Gap Is the Real Story
The numbers on who actually gets scanned are not close. An American Cancer Society analysis published in JAMA, using the 2024 National Health Interview Survey, found that of an estimated 12.76 million Americans eligible under federal criteria, only 18.7 percent reported being up to date with screening. Researchers projected that raising uptake to every eligible person would prevent about 62,110 lung cancer deaths over five years and add roughly 872,270 life years, compared with an estimated 14,970 deaths prevented at the observed uptake level.
"It's disappointing that lung cancer screening uptake remains this low," said Dr. Priti Bandi, the study's lead author and scientific director for cancer risk factors and screening surveillance research at the American Cancer Society.
The American Lung Association reports a similar national picture in its most recent State of Lung Cancer report, with 18.2 percent of high-risk individuals screened. Screening rates vary sharply by state. The association's national report put the highest rate in Rhode Island at 31 percent and the lowest in Wyoming at 9.7 percent, while its Texas report placed that state 46th of 51 for screening at 12 percent and near the bottom nationally for early-stage diagnosis, survival, and surgical treatment. The association cautions that this year's screening figures reflect a correction to its data source and should not be compared with its earlier reports.
By contrast, breast and colorectal cancer screening reach far higher shares of eligible adults. Lung screening does not, despite lung cancer remaining the leading cause of cancer death in the United States.
Inside the Scan Itself
A low-dose CT is a short procedure. The patient lies on a table, holds their breath for a few seconds, and passes through the scanner. There is no injection, no contrast dye, and no needle. The entire appointment usually takes well under an hour, and the imaging portion takes only minutes.
The radiation dose is a fraction of a standard diagnostic chest CT, which is what the term low dose refers to. The scan produces detailed cross-sectional images of the lungs that can detect nodules far smaller than those visible on a chest X-ray.
The mortality benefit is documented. The National Lung Screening Trial, which enrolled 53,454 participants, reported a 20 percent relative reduction in lung cancer mortality with low-dose CT compared with chest radiography, the finding that drove screening recommendations in the first place. Modeling commissioned by the task force estimated that screening under the current criteria would reduce lung cancer mortality by 13 percent and avert about 503 lung cancer deaths per 100,000 people aged 45 to 90 over a lifetime of screening.
Screening also carries real harms, including false positive results that lead to further imaging or invasive procedures, incidental findings, overdiagnosis, and radiation exposure. The task force concluded that the net benefit is moderate for people who meet the criteria, which is why the decision is intended to be shared with a clinician.
Early detection matters because the stage at which it is detected determines the outcome. Lung cancer found early can often be treated surgically. Found late, it usually cannot.
The Cost and Access Barriers That Persist
Screening for people who meet the criteria is generally covered without cost-sharing by private plans and by Medicare, because the task force assigned it a B recommendation. That coverage does not guarantee access.
The scan has to be ordered, which means a person needs a clinician who asks about smoking history in enough detail to calculate pack years. The task force advises referral to a center with expertise in lung cancer screening, but these centers are unevenly distributed, often requiring long drives from rural counties. Medicaid programs vary by state in eligibility criteria, prior authorization requirements, and cost-sharing.
There is also a downstream cost problem. A follow-up scan or biopsy after an abnormal finding is diagnostic rather than preventive, and diagnostic imaging is typically subject to deductibles and coinsurance. Patients should ask before the initial scan what the financial implications are if something is found.
The Eligibility Debate Is Not Settled
The 15-year cutoff is itself contested. The American Cancer Society updated its guidelines in 2023 to recommend annual low-dose CT for adults aged 50 to 80 with a 20-pack-year history, regardless of when they quit, removing the years since quitting limit entirely. The National Comprehensive Cancer Network will follow in 2025. The cancer society researchers estimated that about 30 percent or more of the additional benefit available from screening people who are currently ineligible would fall to those with 20 or more pack-years who quit 15 or more years ago.
Federal guidance still uses the 15-year cutoff, and insurance coverage generally follows the federal criteria. Anyone who quit more than 15 years ago and remains concerned should raise it with a clinician rather than assuming a scan is unavailable, since some systems apply the broader cancer society guideline.
Adults who think they may qualify can calculate their pack-year history before the appointment, bring the number to their clinician, and ask directly whether a low-dose CT is appropriate. People who currently smoke should also be offered cessation support at any screening program, since quitting remains the single largest reduction in risk available.
Screening is not a substitute for that. It is a way of catching a disease earlier in people whose risk is already set.
Key Questions Answered
Who qualifies for lung cancer screening? Federal guidance covers adults aged 50 to 80 with at least a 20-pack-year smoking history who currently smoke or quit within the past 15 years. Screening stops once someone has not smoked for 15 years or develops a health problem that substantially limits life expectancy or the ability to have curative lung surgery.
How do I calculate pack-years? Multiply packs smoked per day by years smoked. One pack a day for 20 years equals 20 pack-years, as does two packs a day for 10 years.
How many eligible people actually get screened? An American Cancer Society analysis found that 18.7 percent of eligible adults reported being up to date. The American Lung Association reports 18.2 percent in its most recent state-level report.
What does a low-dose CT involve? A short scan with no needle, no dye, and no injection. The patient holds their breath briefly as they pass through the scanner. Radiation exposure is much lower than a standard chest CT.
Is screening covered by insurance? For people who meet federal criteria, screening is generally covered without cost-sharing by private plans and Medicare. Follow-up diagnostic imaging or biopsy after an abnormal result is billed differently and may be subject to a deductible.
Does quitting more than 15 years ago mean I cannot be screened? Under federal criteria, yes. The American Cancer Society removed the years-since-quitting limit in its 2023 guidelines, so some health systems apply broader criteria. Anyone in that situation should discuss it with a clinician.
Does screening replace quitting? No. Quitting remains the most effective way to reduce lung cancer risk. Screening programs are expected to offer cessation support to participants who still smoke.
