title: A population-based cohort study of chest x-ray screening in smokers: lung cancer detection findings and follow-up.
abstract: BACKGROUND
  Case-control studies of mass screening for lung cancer (LC) by chest x-rays (CXR) performed in the 1990s in scarcely defined Japanese target populations indicated significant mortality reductions, but these results are yet to be confirmed in western countries. To ascertain whether CXR screening decreases LC mortality at community level, we studied a clearly defined population-based cohort of smokers invited to screening. We present here the LC detection results and the 10-year survival rates.
  
  
  METHODS
  The cohort of all smokers of > 10 pack-years resident in 50 communities of Varese, screening-eligible (n = 5,815), in July 1997 was invited to nonrandomized CXR screening. Self-selected participants (21% of cohort) underwent screening in addition to usual care; nonparticipants received usual care. The cohort was followed-up until December 2010. Kaplan-Meier LC-specific survival was estimated in participants, in nonparticipants, in the whole cohort, and in an uninvited, unscreened population (control group).
  
  
  RESULTS
  Over the initial 9.5 years of study, 67 LCs were diagnosed in screening participants (51% were screen-detected) and 178 in nonparticipants. The rates of stage I LC, resectability and 5-year survival were nearly twice as high in participants (32% stage I; 48% resected; 30.5% 5-year survival) as in nonparticipants (17% stage I; 27% resected; 13.5% 5-year survival). There were no bronchioloalveolar carcinomas among screen-detected cancers, and median volume doubling time of incidence screen-detected LCs was 80 days (range, 44-318), suggesting that screening overdiagnosis was minimal. The 10-year LC-specific survival was greater in screening participants than in nonparticipants (log-rank, p = 0.005), and greater in the whole cohort invited to screening than in the control group (log-rank, p = 0.001). This favourable long-term effect was independently related to CXR screening exposure.
  
  
  CONCLUSIONS
  In the setting of CXR screening offered to a population-based cohort of smokers, screening participants who were diagnosed with LC had more frequently early-stage resectable disease and significantly enhanced long-term LC survival. These results translated into enhanced 10-year LC survival, independently related to CXR screening exposure, in the entire population-based cohort. Whether increased long-term LC-specific survival in the cohort corresponds to mortality reduction remains to be evaluated.
  
  
  BACKGROUND
  ISRCTN90639073.
authors.affiliation: Center for Thoracic Surgery, University of Insubria, Varese, Italy. lorenzo.dominioni@uninsubria.it
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Dominioni
authors.forename: Nicola
authors.initials: N
authors.lastname: Rotolo
authors.forename: William
authors.initials: W
authors.lastname: Mantovani
authors.forename: Albino
authors.initials: A
authors.lastname: Poli
authors.forename: Salvatore
authors.initials: S
authors.lastname: Pisani
authors.forename: Valentina
authors.initials: V
authors.lastname: Conti
authors.forename: Massimo
authors.initials: M
authors.lastname: Paolucci
authors.forename: Fausto
authors.initials: F
authors.lastname: Sessa
authors.forename: Antonio
authors.initials: A
authors.lastname: Paddeu
authors.forename: Vincenzo
authors.initials: V
authors.lastname: D'Ambrosio
authors.forename: Andrea
authors.initials: A
authors.lastname: Imperatori
mesh_terms: D000368:Aged; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007558:Italy; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000401:mortality; D008297:Male; D008400:Mass Chest X-Ray; D008875:Middle Aged; D012907:Smoking / Q000009:adverse effects*; D015996:Survival Rate