title: Lung cancers diagnosed at annual CT screening: volume doubling times.
abstract: OBJECTIVE
  To empirically address the distribution of the volume doubling time (VDT) of lung cancers diagnosed in repeat annual rounds of computed tomographic (CT) screening in the International Early Lung Cancer Action Program (I-ELCAP), first and foremost with respect to rates of tumor growth but also in terms of cell types.
  
  
  METHODS
  All CT screenings in I-ELCAP from 1993 to 2009 were performed according to HIPAA-compliant protocols approved by the institutional review boards of the collaborating institutions. All instances of first diagnosis of primary lung cancer after a negative screening result 7-18 months earlier were identified, with symptom-prompted diagnoses included. Lesion diameter was calculated by using the measured length and width of each cancer at the time when the nodule was first identified for further work-up and at the time of the most recent prior screening, 7-18 months earlier. The length and width were measured a second time for each cancer, and the geometric mean of the two calculated diameters was used to calculate the VDT. The χ(2) statistic was used to compare the VDT distributions.
  
  
  RESULTS
  The median VDT for 111 cancers was 98 days (interquartile range, 108). For 56 (50%) cancers it was less than 100 days, and for three (3%) cancers it was more than 400 days. Adenocarcinoma was the most frequent cell type (50%), followed by squamous cell carcinoma (19%), small cell carcinoma (19%), and others (12%). Lung cancers manifesting as subsolid nodules had significantly longer VDTs than those manifesting as solid nodules (P < .0001).
  
  
  CONCLUSIONS
  Lung cancers diagnosed in annual repeat rounds of CT screening, as manifest by the VDT and cell-type distributions, are similar to those diagnosed in the absence of screening.
authors.affiliation: Department of Radiology, Mount Sinai School of Medicine, New York, NY 10029, USA. Henschke@mountsinai.org
authors.forename: Claudia I
authors.initials: CI
authors.lastname: Henschke
authors.forename: David F
authors.initials: DF
authors.lastname: Yankelevitz
authors.forename: Rowena
authors.initials: R
authors.lastname: Yip
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Reeves
authors.forename: Ali
authors.initials: A
authors.lastname: Farooqi
authors.forename: Dongming
authors.initials: D
authors.lastname: Xu
authors.forename: James P
authors.initials: JP
authors.lastname: Smith
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Libby
authors.forename: Mark W
authors.initials: MW
authors.lastname: Pasmantier
authors.forename: Olli S
authors.initials: OS
authors.lastname: Miettinen
mesh_terms: D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D008297:Male; D008403:Mass Screening / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods*; D047368:Tumor Burden