title: CT screening for lung cancer brings forward early disease. The randomised Danish Lung Cancer Screening Trial: status after five annual screening rounds with low-dose CT.
abstract: BACKGROUND
  The effects of low-dose CT screening on disease stage shift, mortality and overdiagnosis are unclear. Lung cancer findings and mortality rates are reported at the end of screening in the Danish Lung Cancer Screening Trial.
  
  
  METHODS
  4104 men and women, healthy heavy smokers/former smokers were randomised to five annual low-dose CT screenings or no screening. Two experienced chest radiologists read all CT scans and registered the location, size and morphology of nodules. Nodules between 5 and 15 mm without benign characteristics were rescanned after 3 months. Growing nodules (>25% volume increase and/or volume doubling time<400 days) and nodules >15 mm were referred for diagnostic workup. In the control group, lung cancers were diagnosed and treated outside the study by the usual clinical practice.
  
  
  RESULTS
  Participation rates were high in both groups (screening: 95.5%; control: 93.0%; p<0.001). Lung cancer detection rate was 0.83% at baseline and mean annual detection rate was 0.67% at incidence rounds (p=0.535). More lung cancers were diagnosed in the screening group (69 vs. 24, p<0.001), and more were low stage (48 vs 21 stage I-IIB non-small cell lung cancer (NSCLC) and limited stage small cell lung cancer (SCLC), p=0.002), whereas frequencies of high-stage lung cancer were the same (21 vs 16 stage IIIA-IV NSCLC and extensive stage SCLC, p=0.509). At the end of screening, 61 patients died in the screening group and 42 in the control group (p=0.059). 15 and 11 died of lung cancer, respectively (p=0.428).
  
  
  CONCLUSIONS
  CT screening for lung cancer brings forward early disease, and at this point no stage shift or reduction in mortality was observed. More lung cancers were diagnosed in the screening group, indicating some degree of overdiagnosis and need for longer follow-up.
authors.affiliation: Department of Respiratory Medicine, Gentofte University Hospital, Niels Andersens Vej 65, Opgang 30A, 2900 Hellerup, Denmark. zaigham.saghir@gmail.com
authors.forename: Zaigham
authors.initials: Z
authors.lastname: Saghir
authors.forename: Asger
authors.initials: A
authors.lastname: Dirksen
authors.forename: Haseem
authors.initials: H
authors.lastname: Ashraf
authors.forename: Karen Skjøldstrup
authors.initials: KS
authors.lastname: Bach
authors.forename: John
authors.initials: J
authors.lastname: Brodersen
authors.forename: Paul Frost
authors.initials: PF
authors.lastname: Clementsen
authors.forename: Martin
authors.initials: M
authors.lastname: Døssing
authors.forename: Hanne
authors.initials: H
authors.lastname: Hansen
authors.forename: Klaus Fuglsang
authors.initials: KF
authors.lastname: Kofoed
authors.forename: Klaus Richter
authors.initials: KR
authors.lastname: Larsen
authors.forename: Jann
authors.initials: J
authors.lastname: Mortensen
authors.forename: Jakob Fraes
authors.initials: JF
authors.lastname: Rasmussen
authors.forename: Niels
authors.initials: N
authors.lastname: Seersholm
authors.forename: Birgit Guldhammer
authors.initials: BG
authors.lastname: Skov
authors.forename: Hanne
authors.initials: H
authors.lastname: Thorsen
authors.forename: Philip
authors.initials: P
authors.lastname: Tønnesen
authors.forename: Jesper Holst
authors.initials: JH
authors.lastname: Pedersen
mesh_terms: D000368:Aged; D016009:Chi-Square Distribution; D003718:Denmark / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000401:mortality / Q000473:pathology; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D011446:Prospective Studies; D011829:Radiation Dosage; D012907:Smoking / Q000453:epidemiology; D011795:Surveys and Questionnaires; D014057:Tomography, X-Ray Computed / Q000379:methods*