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Final screening round of the NELSON lung cancer screening trial: the effect of a 2.5-year screening interval
  1. Uraujh Yousaf-Khan1,
  2. Carlijn van der Aalst1,
  3. Pim A de Jong2,
  4. Marjolein Heuvelmans3,4,
  5. Ernst Scholten2,5,
  6. Jan-Willem Lammers6,
  7. Peter van Ooijen3,4,
  8. Kristiaan Nackaerts7,
  9. Carla Weenink8,
  10. Harry Groen9,
  11. Rozemarijn Vliegenthart3,4,
  12. Kevin ten Haaf1,
  13. Matthijs Oudkerk3,4,
  14. Harry de Koning1
  1. 1Department of Public Health, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, The Netherlands
  2. 2Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
  3. 3Department of Radiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
  4. 4University of Groningen, University Medical Center Groningen, Center for Medical Imaging—North East Netherlands, Groningen, The Netherlands
  5. 5Department of Radiology, Kennemer Gasthuis, Haarlem, The Netherlands
  6. 6Department of Pulmonary Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
  7. 7Department of Pulmonary Medicine, University Hospital Gasthuisberg, Leuven, Belgium
  8. 8Department of Pulmonary Medicine, Kennemer Gasthuis, Haarlem, The Netherlands
  9. 9Department of Pulmonary Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
  1. Correspondence to Uraujh Yousaf-Khan, Erasmus Medical Center, University Medical Center Rotterdam, Department of Public Health, Room Na 22-09, P.O. Box 2040, Rotterdam 3000 CA, The Netherlands; a.yousaf{at}


Background In the USA annual lung cancer screening is recommended. However, the optimal screening strategy (eg, screening interval, screening rounds) is unknown. This study provides results of the fourth screening round after a 2.5-year interval in the Dutch-Belgian Lung Cancer Screening trial (NELSON).

Methods Europe's largest, sufficiently powered randomised lung cancer screening trial was designed to determine whether low-dose CT screening reduces lung cancer mortality by ≥25% compared with no screening after 10 years of follow-up. The screening arm (n=7915) received screening at baseline, after 1 year, 2 years and 2.5 years. Performance of the NELSON screening strategy in the final fourth round was evaluated. Comparisons were made between lung cancers detected in the first three rounds, in the final round and during the 2.5-year interval.

Results In round 4, 46 cancers were screen-detected and there were 28 interval cancers between the third and fourth screenings. Compared with the second round screening (1-year interval), in round 4 a higher proportion of stage IIIb/IV cancers (17.3% vs 6.8%, p=0.02) and higher proportions of squamous-cell, bronchoalveolar and small-cell carcinomas (p=0.001) were detected. Compared with a 2-year interval, the 2.5-year interval showed a higher non-significant stage distribution (stage IIIb/IV 17.3% vs 5.2%, p=0.10). Additionally, more interval cancers manifested in the 2.5-year interval than in the intervals of previous rounds (28 vs 5 and 28 vs 19).

Conclusions 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.

Trial registration number ISRCTN63545820.

  • Tobacco and the lung
  • Lung Cancer
  • Non-Small Cell Lung Cancer
  • Small Cell Lung Cancer
  • Clinical Epidemiology

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  • Contributors Involvement in the conception, hypothesis delineation and design of the study: UY-K, CvdA, MO and HdK. Acquisition of the data or the analysis and interpretation of such information: UY-K, CvdA, PAdJ, ES, PvO, RV, MO and HdK. Writing the article or substantial involvement in its revision prior to submission: UY-K, CvdA, PAdJ, MH, ES, J-WL, PvO, KN, CW, HG, RV, KtH, MO and HdK. UY-K had full access to all the data in the study and had final responsibility for the decision to submit for publication.

  • Funding The NELSON trial is supported by: The NELSON trial is presently supported by “The Netherlands Organisation for Health Research and Development” (ZonMw). Siemens Germany provided four digital workstations and LungCARE for the performance of 3D-measurements of the nodules. Roche diagnostics provided a grant for the performance of proteomics research.

  • Competing interests KN reports grants from Belgian Foundation against Cancer, grants from Flemish League against Cancer, during the conduct of the study. HG reports others from MSD, EliLilly, Merck, Pfizer, Roche, outside the submitted work. HdK reports grants from Roche Diagnostics, other from Siemens Germany, during the conduct of the study; personal fees from MD Anderson/Health sciences, outside the submitted work. UY-K, KtH and CvdA report grants from Roche Diagnostics, and other from Siemens Germany, during the conduct of the study.

  • Patient consent Obtained.

  • Ethics approval The NELSON trial was approved by the Dutch Minister of Health and the ethics board at each participating centre. The NELSON trial is registered at under number: ISRCTN63545820.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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