Lung cancer screening is recommended for adults aged 50 to 80 who have a smoking history of at least 20 pack-years and either still smoke or quit within the past 15 years. These are the criteria from the U.S. Preventive Services Task Force (USPSTF), which form the basis for most insurance coverage decisions. But newer guidelines from the American Cancer Society have expanded eligibility further, and understanding where you fall can make a real difference: screening with low-dose CT scans reduces lung cancer deaths by 16% to 20%.
The Three Criteria You Need to Meet
Under current USPSTF recommendations, you qualify for annual lung cancer screening if you meet all three of these conditions:
- Age: Between 50 and 80 years old
- Smoking history: At least 20 pack-years
- Current or recent smoker: You either smoke now or quit within the past 15 years
If you meet all three, the recommendation is a yearly low-dose CT scan (LDCT) of the chest. This is a quick, painless scan that uses roughly one-fifth the radiation of a standard chest CT. There’s no injection, no fasting, and the scan itself takes less than a minute.
Screening stops when you turn 81, when you’ve been smoke-free for 15 or more years, or if you develop a health condition that would prevent you from undergoing treatment if cancer were found. In practice, clinicians also weigh whether your overall life expectancy is less than about five years, since screening is most valuable when you’d be healthy enough to benefit from early treatment.
How to Calculate Your Pack-Years
A pack-year equals one pack of cigarettes (20 cigarettes) smoked per day for one year. To find your number, multiply the packs you smoked per day by the number of years you smoked. Someone who smoked one pack a day for 20 years has a 20 pack-year history. So does someone who smoked two packs a day for 10 years, or half a pack a day for 40 years.
If your smoking varied over time, you can break it into periods. Maybe you smoked a pack a day for 12 years, then half a pack for 16 years. That’s 12 plus 8, giving you 20 pack-years. The threshold for screening eligibility is 20 pack-years under current guidelines.
The American Cancer Society’s Broader Criteria
In late 2023, the American Cancer Society updated its lung cancer screening guidelines with one major change: it removed the 15-year quit requirement entirely. Under these guidelines, anyone aged 50 to 80 with at least 20 pack-years of smoking history qualifies, regardless of how long ago they quit.
This matters because previous guidelines assumed that lung cancer risk steadily drops after quitting. Newer evidence shows that assumption is wrong. Many people who quit decades ago still carry significant risk, and the old cutoff was excluding a large group of people who could benefit from early detection. If you quit smoking 20 or 30 years ago but have 20 or more pack-years in your history, the American Cancer Society now says you should be screened.
The practical catch is that insurance coverage typically follows the USPSTF criteria, not the American Cancer Society’s. So your doctor may recommend screening based on the broader guidelines, but coverage could depend on which set of criteria your insurer uses.
What Medicare and Insurance Cover
Medicare Part B covers annual LDCT lung cancer screening at no cost to you, as long as your provider accepts Medicare assignment. Medicare’s eligibility window is ages 50 to 77 (slightly narrower than the USPSTF’s upper limit of 80), and you must meet the 20 pack-year and 15-year quit criteria. Before your first screening, Medicare requires a shared decision-making visit with your provider to discuss the benefits and risks.
Under the Affordable Care Act, most private insurance plans are also required to cover USPSTF-recommended preventive services without cost-sharing. That means if you meet the USPSTF criteria, your annual screening should be covered with no copay or deductible. You’ll need a written order from your provider for each screening.
What the Scan Can and Can’t Tell You
LDCT is far better at catching lung cancer early than chest X-rays, which were studied in the 1970s and showed no mortality benefit at all. The low-dose CT creates detailed cross-sectional images of the lungs and can spot small nodules, which are tiny spots that may or may not be cancerous.
Most findings are benign. Radiologists classify results using a system called Lung-RADS, which ranges from category 1 (negative, no nodules) to category 4B (very suspicious). Categories 1 and 2 simply mean you continue with your next annual scan in 12 months. Category 3, “probably benign,” leads to a follow-up scan in six months. Categories 4A and 4B may require additional imaging or a biopsy.
False positives are common. Across major screening trials, between 10% and 29% of initial scans flagged something that turned out not to be cancer. In the largest U.S. trial, for every 1,000 people screened, 17 underwent an invasive follow-up procedure due to a false positive, and fewer than one experienced a major complication. That’s an important tradeoff to understand: screening saves lives, but it also creates anxiety and additional testing for a meaningful number of people who don’t have cancer.
Who Shouldn’t Be Screened
Screening isn’t recommended if you’re already experiencing symptoms of lung cancer, such as a persistent cough, coughing up blood, unexplained weight loss, or chest pain. Those symptoms call for diagnostic testing, not a screening scan.
People with conditions that substantially limit life expectancy or make lung surgery impossible are generally not good candidates. In a large Veterans Health Administration study, clinicians were more likely to determine screening was inappropriate for patients with an estimated three-year risk of dying from non-lung-cancer causes, those with interstitial lung disease (scarring of the lungs), and those 75 or older with significant other health problems. The underlying logic is straightforward: screening helps most when finding cancer early would actually change the outcome.
Most Eligible People Aren’t Getting Screened
Despite clear guidelines, only about 22% of eligible people have completed lung cancer screening in studies tracking real-world uptake. Rates have improved over time, climbing from under 10% to around 35% in some health systems, but large gaps remain. Black individuals, Medicaid recipients, people of Middle Eastern or Arab ethnicity, and those living in economically deprived areas are all significantly less likely to be screened.
If you meet the criteria, the simplest step is to bring it up with your primary care provider. Many eligible people don’t get screened simply because no one mentions it. Knowing your pack-year history before the visit makes the conversation faster and gives your provider what they need to place the order.