What are the criteria for screening for lung cancer?

Lung Cancer Screening Criteria

Annual lung cancer screening with low-dose CT (LDCT) is recommended for individuals aged 50-80 years with at least a 20 pack-year smoking history who currently smoke or have quit within the past 15 years. 1

Primary Eligibility Criteria

• The U.S. Preventive Services Task Force (USPSTF) recommends annual screening for lung cancer with LDCT in adults aged 50 to 80 years who have a 20 pack-year smoking history and currently smoke or have quit within the past 15 years 1
• Screening should be discontinued once a person has not smoked for 15 years 2
• Screening should be discontinued if the person develops a health problem that substantially limits life expectancy or the ability/willingness to have curative lung surgery 2

Evolution of Screening Criteria

• The 2013 USPSTF guidelines previously recommended screening for adults aged 55-80 years with at least 30 pack-years of smoking history who currently smoke or quit within the past 15 years 3
• The 2021 USPSTF update expanded eligibility by lowering the age to start screening from 55 to 50 years and reducing the smoking history requirement from 30 to 20 pack-years 1
• This expansion was based on modeling studies showing that starting screening at age 50 with a 20 pack-year threshold would increase the number of lung cancer deaths averted and life-years gained compared to the 2013 criteria 4

Risk-Based Eligibility Considerations

• Individuals who don't meet standard age/smoking criteria but have high risk based on validated clinical risk prediction calculators may be considered for screening 5
• Risk calculators include the PLCOm2012 calculator (≥1.51% 6-year risk threshold) or LCDRAT calculator (≥1.33% 5-year risk threshold) 5
• Risk model-based strategies may be associated with more benefits and fewer radiation-related deaths compared to risk factor-based strategies 4

Contraindications for Screening

• Symptomatic individuals should not enter screening programs but instead receive appropriate diagnostic testing 5, 2
• Individuals with significant comorbidities limiting life expectancy or ability to tolerate treatment should not be screened 5, 2
• Screening is not recommended for individuals younger than 50 years of age or older than 80 years of age with less than 20 pack-years smoking history and no additional risk factors 6

Implementation Requirements

• Screening should be performed in centers with multidisciplinary expertise in lung cancer diagnosis and treatment 2, 6
• Programs should include a team of primary care providers, pulmonologists, thoracic radiologists, thoracic surgeons, nurse navigators, and smoking cessation counselors 6
• Screening programs should develop strategies to identify symptomatic patients who need diagnostic testing rather than screening 5
• Programs should define what constitutes a positive test based on nodule size, with thresholds of 4mm, 5mm, or 6mm in diameter commonly used 5, 2

Benefits and Harms of Screening

• Benefits include reduced lung cancer mortality and increased life-years gained through early detection 4, 7
• Potential harms include radiation exposure from repeated annual scans 5, 2
• False-positive results requiring additional testing and potentially invasive procedures are common 8
• Overdiagnosis of indolent cancers that would not have caused symptoms or death is a concern 5, 2

Important Caveats

• Despite recommendations, uptake of lung cancer screening remains low, with only about 12.5% of eligible individuals receiving recommended screening 3
• Smoking cessation counseling should be provided alongside screening, as screening is not a substitute for smoking cessation 5, 2
• Current screening practices are estimated to avert 19,306 lung cancer deaths and gain 237,564 life-years; screening all eligible individuals could prevent an additional 56,956 lung cancer deaths and gain 751,850 life-years 7
• Recent research suggests that some individuals who don't meet current screening criteria may still be at elevated risk for lung cancer, indicating that prediction models might be needed to identify high-risk subsets of smokers for screening 9