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

Low Dose CT Screening Guidelines for Lung Cancer

Low dose CT screening for lung cancer is recommended annually for adults aged 50-80 years with at least a 20 pack-year smoking history who currently smoke or have quit within the past 15 years, and who do not have significant comorbidities limiting life expectancy or ability to tolerate evaluation and treatment. 1

Eligibility Criteria

Who Should Be Screened:

• Adults aged 50-80 years with:
  • ≥20 pack-year smoking history
  • Currently smoke OR have quit within past 15 years
  • No significant comorbidities limiting life expectancy
  • No symptoms suggestive of lung cancer (symptomatic patients should receive diagnostic testing instead) 2

Who Should NOT Be Screened:

• Individuals with:
  • <20 pack-years of smoking history
  • Age <50 or >80 years
  • Quit smoking >15 years ago
  • Not projected to have high net benefit based on risk calculators 2
• Patients with severe comorbidities that:
  • Substantially limit life expectancy
  • Adversely affect ability to tolerate evaluation of screen-detected findings
  • Adversely affect ability to tolerate treatment of early-stage screen-detected lung cancer 2
  • Examples: advanced liver disease, severe COPD with hypoventilation and hypoxia, NYHA class IV heart failure 2

Screening Protocol

Technical Parameters:

• LDCT should be performed using multidetector scanner with:
  • 120-140 kVp
  • 20-60 mAs
  • Average effective dose ≤1.5 mSv
  • Collimation ≤2.5 mm 2

Nodule Management:

• Definition of positive result: nodule size ≥5 mm found on LDCT 2
• Nodules ≥5 mm warrant 3-month follow-up CT 2
• Nodules ≥15 mm should undergo immediate further diagnostic procedures 2
• Follow-up CT should be done as limited LDCT scan (covering only the nodule, not entire chest) 2

Implementation Requirements

Pre-Screening Process:

1. Symptom Assessment: Programs must develop strategies to identify symptomatic patients who require diagnostic testing rather than screening 2
2. Shared Decision-Making: Required before initiating screening, including: 2, 1
   • Determination of screening eligibility
   • Discussion of benefits and harms using decision aids
   • Information about potential findings and follow-up testing
   • Need for annual screening
   • Confirmation of willingness to accept treatment for screen-detected cancer
   • Smoking cessation counseling

Program Structure:

• Screening should be performed in centers with multidisciplinary expertise in:
  • Pulmonology
  • Radiology
  • Thoracic surgery
  • Oncology 1
• Programs should collect data for quality improvement 3

Benefits and Harms

Benefits:

• Reduces lung cancer mortality by approximately 20% through early detection 1, 4
• Expanded eligibility criteria (age 50-80, ≥20 pack-years) increases:
  • Screening eligibility (20.6%-23.6% vs 14.1% under previous guidelines)
  • Lung cancer deaths averted (469-558 per 100,000 vs 381 per 100,000)
  • Life-years gained (6018-7596 per 100,000 vs 4882 per 100,000) 4

Potential Harms:

• False-positive results (1.9-2.5 per person screened)
• Overdiagnosed lung cancer cases (83-94 per 100,000)
• Radiation-related lung cancer deaths (29.0-42.5 per 100,000)
• Invasive procedures for benign findings 4

Special Considerations

Risk Assessment Tools:

• Life-year gained calculators or lung cancer risk calculators may help identify:
  • Individuals with high net benefit
  • Those unlikely to benefit
  • Those with closer balance of benefits to harms 2
• These tools can help tailor shared decision-making discussions 2

Smoking Cessation:

• Smoking cessation counseling is a critical component of any lung cancer screening program
• Current smokers should be vigorously urged to enter smoking cessation programs 1
• Screening should not be considered a substitute for smoking cessation 1

Evolution of Guidelines

The current recommendations represent an expansion from earlier guidelines (2013-2015) that recommended screening for ages 55-80 years with ≥30 pack-year history. The 2021 USPSTF update and other recent guidelines expanded eligibility to ages 50-80 years with ≥20 pack-year history, increasing screening access while maintaining mortality benefit 1, 5.