What are the guidelines for low-dose computed tomography (low-dose CT) screening for lung cancer in smokers?

Low-Dose CT Screening Guidelines for Lung Cancer in Smokers

Annual low-dose CT screening is strongly recommended for individuals aged 50-80 years with a ≥20 pack-year smoking history who currently smoke or have quit within the past 15 years. 1, 2, 3

Eligibility Criteria

Recommended for Screening:

• Primary Criteria:

  • Age 50-80 years 2, 1
  • Smoking history ≥20 pack-years 1, 3
  • Current smokers or former smokers who quit within the past 15 years 2, 1

• Highest Risk Group (Strongest Evidence):

  • Age 55-77 years with ≥30 pack-years smoking history 2, 4

• Additional Risk Assessment:

  • Validated risk calculators may help identify individuals who would benefit from screening 2
  • Risk factors include: radon exposure, occupational exposures, personal cancer history, family history of lung cancer, COPD, or pulmonary fibrosis 4

Not Recommended for Screening:

• Individuals younger than 50 or older than 80 years 2
• Those with less than 20 pack-years smoking history and no additional risk factors 4
• Individuals with comorbidities that substantially limit life expectancy or ability to tolerate evaluation/treatment 2, 1
• Symptomatic individuals (should receive diagnostic testing instead) 2

Screening Protocol

Frequency and Duration:

• Annual screening is recommended 2, 4
• Screening should be discontinued when:
  • Individual develops health problems that substantially limit life expectancy 1
  • Individual develops health problems that limit ability/willingness to undergo curative lung surgery 2, 1
  • The 2023 American Cancer Society guideline update notably removed the 15-year quit criterion for discontinuation, recommending continued screening for eligible former smokers regardless of years since quitting 3

Implementation Requirements:

• Screening should be conducted in centers with multidisciplinary expertise 2, 5
• Required components:
  1. Shared decision-making discussion prior to screening 2
  2. Assessment for symptoms suggesting lung cancer 2
  3. Discussion of benefits, harms, and follow-up requirements 2
  4. Smoking cessation counseling for current smokers 2, 3
  5. Confirmation of willingness to accept treatment if cancer is detected 2

Nodule Management

• Programs should define a positive test based on nodule size threshold (acceptable thresholds: 4mm, 5mm, or 6mm) 2
• For part-solid nodules, size should be based on solid component 2
• The Lung-RADS reporting system commonly uses 6mm at baseline and 4mm for new nodules on annual scans 2
• A comprehensive approach to nodule management with multi-disciplinary expertise is essential 2, 5

Benefits and Risks

Benefits:

• Reduces lung cancer mortality by approximately 20% through early detection 1, 5
• Greatest benefit seen in highest-risk individuals 6

Risks:

• False positives (particularly in lower-risk individuals) 6
• Radiation exposure 2
• Potential overdiagnosis of indolent cancers 2
• Unnecessary invasive procedures 5

Important Considerations

• The 2021 USPSTF update expanded eligibility from the previous 2013 recommendation (which was age 55-80 with ≥30 pack-years) to age 50-80 with ≥20 pack-years 1
• The 2023 American Cancer Society guideline update removed years since quitting smoking as a criterion to stop screening 3
• Screening should not be considered a substitute for smoking cessation 4
• Risk-based targeting may improve efficiency of screening programs by focusing on those most likely to benefit 6