Lung cancer screening
Recommendations
USPSTF2021Grade B
Annual low-dose CT for adults 50-80 with ≥20 pack-year history who currently smoke or quit within 15 years. Stop once quit ≥15y or limited life expectancy.
Verify at USPSTF (opens in a new tab)ACS2023Grade Strong recommendation, moderate-quality evidence
Annual low-dose CT for asymptomatic adults 50 to 80 who currently smoke or formerly smoked with a ≥20 pack-year history. Unlike USPSTF, years since quitting is not a reason to start or stop screening. Begin with shared decision-making, counsel current smokers to quit, and do not screen people whose comorbidities substantially limit life expectancy.
Verify at ACS (opens in a new tab)CHEST (ACCP)2021Grade Strong to weak, moderate-quality evidence
Offer annual low-dose CT to ages 55 to 77 with ≥30 pack-years who smoke or quit within 15 years (strong), and suggest it for ages 50 to 80 with ≥20 pack-years on the same quit window (weak). Also suggest screening others whom a validated risk calculator projects to have high net benefit (weak). Do not screen people outside these criteria without high projected benefit (strong).
Verify at CHEST (ACCP) (opens in a new tab)Who this applies to
- Adults 50 to 80 with a 20 pack-year history who currently smoke or quit within the past 15 years: annual low-dose CT (USPSTF 2021, Grade B).
- Stop once a person has not smoked for 15 years, or develops a health problem that substantially limits life expectancy or the ability to have curative lung surgery.
- The American Cancer Society (2023) drops the years-since-quitting rule: 50 to 80, 20 pack-years, current or former smoker however long ago they quit, if healthy enough to be treated.
- Medicare covers ages 50 to 77 with 20 pack-years and quitting within 15 years, and requires a documented shared decision-making visit before the first scan.
How it is done in practice
- Pack-years are packs per day multiplied by years smoked: one pack a day for 20 years, or two packs a day for 10.
- Low-dose CT without contrast at a facility that reports with Lung-RADS and has a nodule pathway. Categories 1 and 2 return to annual screening; category 3 gets a 6-month repeat; category 4A gets a 3-month repeat (PET/CT may be added for a solid part of 8 mm or more); 4B and 4X go to diagnostic work-up.
- The decision visit covers the benefit (about a 20 percent reduction in lung cancer death in the National Lung Screening Trial), false positives (common in the first round and mostly resolved with repeat imaging), incidental findings, radiation, and the need to keep coming back every year.
- Offer cessation treatment at every screening visit. It does more than the scan does.
What changed recently
The 2021 update lowered the starting age from 55 to 50 and the pack-year threshold from 30 to 20, roughly doubling the eligible population and closing much of the eligibility gap for women and Black adults. The ACS went further in 2023 by keeping long-quit former smokers eligible.
Points that matter in clinic
- Eligibility hinges on an accurate smoking history. Record pack-years and the quit date in structured fields, not free text.
- Symptoms such as hemoptysis or unexplained weight loss mean a diagnostic CT, not a screening one.
- Radon, occupational exposure or family history alone do not qualify a never-smoker under the USPSTF rule.