low - dose CT in lung cancer screening

Last edited 11/2018 and last reviewed 06/2022

Lung cancer is the leading cause of cancer death worldwide - this is mainly due to its advanced stage at the time of diagnosis

• the results of the National Lung Screening Trial (NLST), the US Preventive Services Task Force recommends annual lung cancer screening with CT
  • eligibility for screening
    • aged 55 years through 80 years, have smoked at least 30 pack-years, and currently smoke or have quit within the past 15 years
      
      
• the Dutch-Belgian Lung Cancer Screening trial (NELSON) is the largest European randomised lung cancer screening trial, which was designed to investigate whether (low-dose CT) LDCT screening reduces lung cancer mortality by >=25% compared with no screening after 10 years of follow-up
  • study participants were individuals aged 50-74 years in the Netherlands and Leuven, Belgium, who were considered at high risk for lung cancer based on responses to a general questionnaire
  • participants' records were linked with national registries with 100% coverage regarding cancer diagnosis and date and cause of death, and medical records for deceased lung cancer patients were reviewed by a blinded expert panel through 2013, and for the remaining study years cause of death as reported by Statistics Netherlands was used
  • participants were randomized to CT screening at baseline, 1, 3, and 5.5 years after randomization, or to a control group that received usual care
    • overall 157 lung cancer deaths occurred in the screening arm vs. 250 in the control arm.
    • detection rates varied between 0.8% and 1.1% across screenings (0.9% overall), and the positive predictive value of screening was 41%
    • stage at diagnosis:
      • 69% of the 243 lung cancers detected by screening were detected at stage 1A or 1B, compared with 10%-12% being detected at stage 4 in about 50% of control patient
  • CT screening reduced the risk of death from lung cancer with an overall reduction of 26% at 10 years
    

Analyses of the first three rounds of the NELSON trial indicated that a 2-year interval between the second and the third screening rounds did not lead to a significantly higher proportion of advanced stage lung cancers compared with a 1-year screening interval between the first and second rounds

• An interval of 2.5 years leads to a higher interval cancer rate and a higher proportion of advanced stage disease in the final fourth round compared with the previous screening rounds with a 1-year or 2-year screening interval
  • a 2.5-year interval reduced the effect of screening: the interval cancer rate was higher compared with the 1-year and 2-year intervals, and proportion of advanced disease stage in the final round was higher compared with the previous rounds

Reference:

• Aberle DR, Adams AM, Berg CD, et al., National Lung Screening Trial Research Team. Reduced lung-cancer mortality with low-dose computed tomographic screening. N Engl J Med 2011;365:395-409.
• Yousaf-Khan U et al. Final screening round of the NELSON lung cancer screening trial: the effect of a 2.5-year screening interval Thorax. 2017 Jan;72(1):48-56.
• Yousaf-Khan U et al. Risk stratification based on screening history: the NELSON lung cancer screening study.Thorax. 2017 Sep;72(9):819-824.