title: Benefits and harms of CT screening for lung cancer: a systematic review.
abstract: BACKGROUND
  Lung cancer is the leading cause of cancer death. Most patients are diagnosed with advanced disease, resulting in a very low 5-year survival. Screening may reduce the risk of death from lung cancer.
  
  
  OBJECTIVE
  To conduct a systematic review of the evidence regarding the benefits and harms of lung cancer screening using low-dose computed tomography (LDCT). A multisociety collaborative initiative (involving the American Cancer Society, American College of Chest Physicians, American Society of Clinical Oncology, and National Comprehensive Cancer Network) was undertaken to create the foundation for development of an evidence-based clinical guideline.
  
  
  METHODS
  MEDLINE (Ovid: January 1996 to April 2012), EMBASE (Ovid: January 1996 to April 2012), and the Cochrane Library (April 2012).
  
  
  METHODS
  Of 591 citations identified and reviewed, 8 randomized trials and 13 cohort studies of LDCT screening met criteria for inclusion. Primary outcomes were lung cancer mortality and all-cause mortality, and secondary outcomes included nodule detection, invasive procedures, follow-up tests, and smoking cessation.
  
  
  METHODS
  Critical appraisal using predefined criteria was conducted on individual studies and the overall body of evidence. Differences in data extracted by reviewers were adjudicated by consensus.
  
  
  RESULTS
  Three randomized studies provided evidence on the effect of LDCT screening on lung cancer mortality, of which the National Lung Screening Trial was the most informative, demonstrating that among 53,454 participants enrolled, screening resulted in significantly fewer lung cancer deaths (356 vs 443 deaths; lung cancer−specific mortality, 274 vs 309 events per 100,000 person-years for LDCT and control groups, respectively; relative risk, 0.80; 95% CI, 0.73-0.93; absolute risk reduction, 0.33%; P = .004). The other 2 smaller studies showed no such benefit. In terms of potential harms of LDCT screening, across all trials and cohorts, approximately 20% of individuals in each round of screening had positive results requiring some degree of follow-up, while approximately 1% had lung cancer. There was marked heterogeneity in this finding and in the frequency of follow-up investigations, biopsies, and percentage of surgical procedures performed in patients with benign lesions. Major complications in those with benign conditions were rare.
  
  
  CONCLUSIONS
  Low-dose computed tomography screening may benefit individuals at an increased risk for lung cancer, but uncertainty exists about the potential harms of screening and the generalizability of results.
authors.affiliation: Memorial Sloan-Kettering Cancer Center, New York, New York 10065, USA.
authors.forename: Peter B
authors.initials: PB
authors.lastname: Bach
authors.forename: Joshua N
authors.initials: JN
authors.lastname: Mirkin
authors.forename: Thomas K
authors.initials: TK
authors.lastname: Oliver
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Azzoli
authors.forename: Donald A
authors.initials: DA
authors.lastname: Berry
authors.forename: Otis W
authors.initials: OW
authors.lastname: Brawley
authors.forename: Tim
authors.initials: T
authors.lastname: Byers
authors.forename: Graham A
authors.initials: GA
authors.lastname: Colditz
authors.forename: Michael K
authors.initials: MK
authors.lastname: Gould
authors.forename: James R
authors.initials: JR
authors.lastname: Jett
authors.forename: Anita L
authors.initials: AL
authors.lastname: Sabichi
authors.forename: Rebecca
authors.initials: R
authors.lastname: Smith-Bindman
authors.forename: Douglas E
authors.initials: DE
authors.lastname: Wood
authors.forename: Amir
authors.initials: A
authors.lastname: Qaseem
authors.forename: Frank C
authors.initials: FC
authors.lastname: Detterbeck
mesh_terms: D015331:Cohort Studies; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000401:mortality*; D011829:Radiation Dosage; D016032:Randomized Controlled Trials as Topic; D012306:Risk; D040242:Risk Reduction Behavior; D014057:Tomography, X-Ray Computed / Q000009:adverse effects*