You Quit Smoking Years Ago. You Might Still Need a Lung Scan: Lung Cancer Screening Eligibility

Key Takeaways:

• The US Preventive Services Task Force recommends a yearly low-dose CT scan for adults aged 50 to 80 with at least a 20 pack-year smoking history who smoke now or quit within the past 15 years; the American Cancer Society’s 2023 guideline goes further and no longer uses years since quitting to decide who starts or stops.
• In the NELSON trial of 13,195 men, low-dose CT screening lowered lung cancer deaths by 24 percent at ten years, and in the earlier National Lung Screening Trial, low-dose CT lowered lung cancer deaths by 20 percent compared with chest X-rays.
• In a 2022 national survey, only 18.1 percent of eligible adults were up to date with lung cancer screening, and among eligible people aged 50 to 54 the figure was 6.7 percent.

November is Lung Cancer Awareness Month, and here’s the conversation I wish happened more often. Someone tells me they quit smoking ten years ago and assumes that chapter is closed, so lung cancer screening never comes up. Then they’re surprised to learn they still qualify for a yearly scan. Lung cancer screening eligibility is simpler than most people think. Under the US Preventive Services Task Force, you qualify if you’re 50 to 80 years old, have a smoking history of at least 20 pack-years, and either still smoke or quit within the last 15 years. A pack-year is just packs per day multiplied by years smoked. A pack a day for 20 years is 20 pack-years. So is two packs a day for 10 years, or half a pack a day for 40. Plenty of people who think of themselves as “light” or long-ago smokers cross that line. The American Cancer Society’s 2023 guideline goes a step further: for people who used to smoke, it no longer uses years since quitting at all to decide who starts or stops screening. And here’s the number that stops me: in a 2022 national survey, fewer than one in five eligible adults were up to date with their screening. Among eligible people in their early fifties, it was fewer than one in fourteen.

The screening is a low-dose CT scan of the chest. It takes a few minutes, needs no needles or dye, and uses roughly a quarter or less of the radiation of a standard chest CT. The evidence behind it comes from two big randomized trials. The National Lung Screening Trial enrolled 53,454 people at high risk and gave them three yearly scans with either low-dose CT or a chest X-ray. The CT group had 20 percent fewer deaths from lung cancer, and about 7 percent fewer deaths from any cause. The European NELSON trial compared CT screening with no screening in 13,195 men and found 24 percent fewer lung cancer deaths at ten years; in a smaller group of women the estimate was even larger, though less certain. I want to be just as honest about the downside. Across three rounds in the American trial, about a quarter of CT scans found something, and 96 percent of those findings were not cancer. Most turn out to be harmless scars or tiny nodules that a repeat scan shows aren’t growing. NELSON’s approach, which measured nodule size precisely, referred only about 2 percent of people for a suspicious nodule. False alarms are real, and they’re why screening should be done through a program that knows how to manage them.

Do I qualify for lung cancer screening if I quit smoking?

If you’re 50 to 80 and have at least 20 pack-years, there’s a good chance you do, and it’s worth asking even if you quit long ago. I’d rather find a small spot on a low-dose CT than a big one on a chest X-ray ordered for a cough. Start with the math tonight: packs per day times years smoked. Then ask your clinician about a yearly low-dose CT and the shared decision-making visit that usually comes first, where you talk through benefits, false alarms and what happens if something shows up. If you quit more than 15 years ago, bring up the newer American Cancer Society guidance, but call your insurance before you book: Medicare and most plans still use the 15-year cutoff, so the scan may not be covered for you. Screening is yearly, not a one-time scan. If you still smoke, a clean scan isn’t permission to keep going; quitting is still the single biggest thing you can do for your lungs, and screening programs can connect you with help. Screening isn’t meant for people whose other health problems would make lung surgery or a longer life unlikely. Do the pack-year math. Then send this to someone you know who quit years ago.

References:

1. Krist, A. H., Davidson, K. W., Mangione, C. M., Barry, M. J., Cabana, M., Caughey, A. B., et al. (2021). Screening for lung cancer: US Preventive Services Task Force recommendation statement. JAMA, 325(10), 962-970.
2. Wolf, A. M. D., Oeffinger, K. C., Shih, T. Y., Walter, L. C., Church, T. R., Fontham, E. T. H., et al. (2024). Screening for lung cancer: 2023 guideline update from the American Cancer Society. CA: A Cancer Journal for Clinicians, 74(1), 50-81.
3. Bandi, P., Star, J., Ashad-Bishop, K., Kratzer, T., Smith, R., & Jemal, A. (2024). Lung cancer screening in the US, 2022. JAMA Internal Medicine, 184(8), 882-891.
4. Aberle, D. R., Adams, A. M., Berg, C. D., Black, W. C., Clapp, J. D., Fagerstrom, R. M., et al. (2011). Reduced lung-cancer mortality with low-dose computed tomographic screening. The New England Journal of Medicine, 365(5), 395-409.
5. de Koning, H. J., van der Aalst, C. M., de Jong, P. A., Scholten, E. T., Nackaerts, K., Heuvelmans, M. A., et al. (2020). Reduced lung-cancer mortality with volume CT screening in a randomized trial. The New England Journal of Medicine, 382(6), 503-513.