CT Lung Cancer Screening Recommendations
Annual low-dose CT (LDCT) screening is recommended for individuals aged 55-74 years with a minimum 30 pack-year smoking history who currently smoke or have quit within the past 15 years. 1, 2
Eligibility Criteria
- Screening is recommended for high-risk individuals aged 55-74 years with ≥30 pack-year smoking history who currently smoke or have quit within the past 15 years 1
- Some guidelines have expanded criteria to include individuals aged 50-80 years with ≥20 pack-year smoking history who currently smoke or have quit within the past 15 years 2
- Additional risk factors that may warrant screening in individuals with >20 pack-year smoking history and age >50 years include: 1
- Personal cancer history (survivors of lung cancer, lymphomas, head and neck cancers)
- Personal history of lung disease (COPD, pulmonary fibrosis)
- Family history of lung cancer in a first-degree relative
Technical Specifications for LDCT
- Screening should use a multidetector scanner with the following parameters: 1, 2
- 120-140 kVp
- 20-60 mAs
- Average effective dose of 1.5 mSv or less
- Collimation of 2.5 mm or less
Management of Screen-Detected Nodules
- Nodules ≥5 mm require a 3-month follow-up CT 1, 3
- Nodules ≥15 mm should undergo immediate further diagnostic procedures 1, 3
- Follow-up CT should be done as a limited LDCT scan covering only the nodule area 1
Implementation Considerations
- Screening should be performed in centers with multidisciplinary expertise in lung cancer diagnosis and treatment 1, 3
- Smoking cessation counseling should be provided alongside screening 1, 2
- Lung cancer screening is not a substitute for smoking cessation 1, 2
- Individuals who are screened should be enrolled in a registry to capture data on follow-up testing, radiation exposure, patient experience, and smoking behavior 1, 3
Contraindications for Screening
- Individuals with severe comorbidities that would preclude potentially curative treatment or limit life expectancy 1, 2
- Individuals who quit smoking more than 15 years ago 1, 2
- Symptomatic individuals should receive appropriate diagnostic testing instead of screening 2
- Chest X-ray is NOT recommended for lung cancer screening 3
Benefits and Harms
Benefits
- 20-24% reduction in lung cancer mortality compared to no screening 4
- Early detection leads to better survival outcomes: patients diagnosed with stage 1A lung cancer have >75% 5-year survival rate, compared to <5% at stage 4 4
Potential Harms
- Radiation exposure from repeated annual scans (estimated radiation-related lifetime attributable risk to develop cancer is below 0.25% for women and about 0.1% for men) 5
- False-positive results (in the National Lung Screening Trial, 27% of scans were positive, and 96% of those were false positive) 1
- Potential for overdiagnosis of indolent cancers 2
- Possible complications from invasive diagnostic procedures following positive screens 2
Emerging Approaches
- Risk prediction models (such as the PLCOm2012 calculator with a 6-year risk threshold of 1.51%) may improve screening efficiency 2, 6
- Extending screening intervals for low-risk individuals may reduce costs and associated harms 4
- Volumetric-based measurement and follow-up can greatly reduce false-positive results 4