THE GOOD

1. Benefits of LDCT Screening:

• The national lung screening trial demonstrated a 20% reduction in lung cancer mortality with LDCT screening compared with chest xray. 
• The “number needed to screen” (NNS) is a key metric, representing the number of screenings required to prevent one lung cancer death. It found that former smokers needed 462 screenings to prevent one lung cancer death versus 230 in current smokers to prevent one lung cancer death. 
• Modeling efforts estimate a 14% population reduction in lung cancer mortality with LDCT screening, assuming 100% compliance.
• The NLST showed 62% of LDCT-detected cancers were in stage I, and LDCT test sensitivity was 93.7%.

THE BAD

2. Harms of Screening – False-Positive Screens:
   • False-positive rates for LDCT screening range from 9% to 50%, with a mean/average of 20%.
   • False-positive tests result in follow-up diagnostic procedures, with associated costs and potential complications.
3. Harms of Screening – Overdiagnosis:
   • “Overdiagnosis denotes the concept of a cancer that is detected through screening but would never have become symptomatic or clinically diagnosed otherwise”
   • Overdiagnosis in LDCT screening is estimated at 11%, based on NLST data.
4. Harms of Screening – Radiation Risk:
   • LDCT radiation contributes to an estimated excess lung cancer risk of 0.23% for males and 0.85% for females.
   • The CISNET modeling group estimated a ratio of LDCT-caused (by radiation) to LDCT-averted lung cancer deaths of approximately 1:20.
5. Incidental Findings:
   • LDCT may identify incidental findings unrelated to lung cancer, such as emphysema or coronary artery calcifications.
   • Incidental findings can lead to follow-up procedures and increased medical care costs. although beneficial sometimes  there are easier and less invasive ways to be diagnosed. 
6. Uncertainties and Research Gaps:
   • Long-term effects of LDCT screening in the population setting remain uncertain and rely on modeling.

CHALLENGES

1. The greatest unknown for LDCT lung cancer screening is its translation from research settings to routine-use population settings.
2. We need to consider monitoring the rate of invasive procedures for falsely positive screens and assessing complication rates. This is essential for patient safety.