• Genomic Epidemiology Branch, International Agency for Research on Cancer, Lyon, France. Electronic address: robbinsh@iarc.fr.
• Genomic Epidemiology Branch, International Agency for Research on Cancer, Lyon, France.
• Prevention and Early Detection Theme, NIHR Manchester Biomedical Research Centre, Manchester, UK; Division of Infection, Immunity and Respiratory Medicine, University of Manchester, Manchester, UK.
• Division of Infection, Immunity and Respiratory Medicine, University of Manchester, Manchester, UK; Manchester Thoracic Oncology Centre, Manchester University NHS Foundation Trust, Manchester, UK.
• Manchester Thoracic Oncology Centre, Manchester University NHS Foundation Trust, Manchester, UK.
• Prevention and Early Detection Theme, NIHR Manchester Biomedical Research Centre, Manchester, UK; Division of Evolution and Genomic Sciences, University of Manchester, Manchester, UK.
• Prevention and Early Detection Theme, NIHR Manchester Biomedical Research Centre, Manchester, UK; Division of Cancer Sciences, University of Manchester, Manchester, UK.
• Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, MD, USA.

BACKGROUND: The frequency of lung cancer detection in the Manchester Lung Health Checks (MLHCs), a community-based screening service, was higher than in the National Lung Screening Trial (NLST) over two screening rounds. We aimed to identify the potential reasons for this difference.

METHODS: We analyzed individual-level data from NLST and MLHCs, restricting to MLHCs participants who met NLST eligibility criteria. We calculated 'detection ratios' comparing the frequency of lung cancer detection in MLHCs vs NLST, first after excluding NLST participants ineligible by MLHC eligibility criteria (6-year lung cancer risk ≥ 1.51 %), and then after standardization to remove the influence of different distributions of baseline lung cancer risk.

RESULTS: Among the 1,079 MLHCs participants who met NLST eligibility criteria, 4.7% were diagnosed with lung cancer over two screening rounds compared with 1.7% in NLST, giving an initial detection ratio of 2.6 (95%CI 2.2-3.0). This was reduced to 2.2 (95%CI 1.3-2.3) after imposing the MLHCs eligibility criterion on NLST, and further to 1.6 (95%CI 1.2-2.1) after removing the influence of different risk distributions. In stratified analyses, the standardized detection ratio was particularly elevated in individuals who were older, living in areas of high socioeconomic disadvantage, or had an FEV/FVC ratio less than 60.

CONCLUSIONS: The 2.6-fold higher lung cancer detection in the community-based MLHCs vs NLST is partly explained by differences in eligibility criteria and baseline risk distributions. The residual 60% increase may relate to higher detection in certain risk groups, including older participants, those with more obstructive lung disease, and those living in areas of socioeconomic disadvantage.