Identifying the population to be targeted in a lung cancer screening programme in Denmark.

Introduction: We assessed the impact of recruitment criteria on lung cancer detection in a future Danish screening programme with low-dose CT.

Methods: We combined data from two Danish population-based health examination surveys with eligibility criteria from seven randomised controlled trials on lung cancer screening. Incident lung cancers were identified by linkage with the National Pathology Data Bank (Patobank). For an average of 4.4 years of follow-up, we calculated sensitivity, specificity, efficient frontier and number needed to screen (NNS) for lung cancer detection.

Results: When applying the different eligibility criteria to the 48 171 persons invited to the two surveys, the number of lung cancer cases identified in the target groups varied from 46 to 68. The National Lung Screening Trial (NLST) criteria had the highest sensitivity of 62.6% (95% CI 52.7 to 71.8) and the Dutch-Belgian NEderlands-Leuvens Screening ONderzoek (NELSON) criteria had the highest specificity 81.6% (95% CI 81.0 to 82.1). Sensitivity was higher for men than for women (NLST criteria 71.7% (95% CI 57.7 to 83.2) and 53.7% (95% CI 39.6 to 67.4), respectively). The NLST criteria identified the target population obtaining the lowest NNS with 46.3. The application of the NLST criteria showed that the higher the sensitivity, the lower the number of false-negative cases and, thus, the lower the NNS.

Conclusions: This study highlights the impact of the definition of the at-risk population on lung cancer screening efficacy. We found lower sensitivity among women regardless of screening criteria used. This should be carefully addressed in a possible screening programme.