Timing of Screening Benefit for Lung Cancer With Low-Dose CT Imaging

Background: Increasing evidence supports lung cancer screening with low-dose CT (LDCT) imaging. However, the benefits of LDCT screening for lung cancer may not be immediate, making it unlikely to benefit patients with limited life expectancy. Research question: What is the time to benefit (TTB) from LDCT screening for individuals at high risk for lung cancer? Study design and methods: Population-based randomized controlled trials of lung cancer screening using LDCT imaging and reporting mortality outcomes were systematically searched in PubMed. TTB was estimated for the National Lung Screening Trial (NLST) and the pooled data from 4 trials using an established analysis framework. Results: This analysis included 4 trials encompassing 64,105 individuals. In the NLST (N = 53,452), to prevent 1 death from lung cancer, 2,000 individuals would need to be screened over 1.78 (95% CI, 0.60-5.27) years. On average, it took 2.87 (95% CI, 1.31-6.32), 4.66 (95% CI, 2.64-8.21), and 8.87 (95% CI, 5.12-15.37) years before 1 death from lung cancer was prevented for every 1,000, 500, and 200 individuals screened, respectively. These findings did not vary when added to other trials. Interpretation: Our findings suggest that the clinical benefits of LDCT screening may not be appropriate for individuals with limited life expectancy. Integrating TTB estimates into patient selection criteria could help maximize the benefits of LDCT screening.