title: Effectiveness of mammography screening in reducing breast cancer mortality in women aged 39-49 years: a meta-analysis.
abstract: BACKGROUND
  Mammography screening of women >50 years of age significantly reduces breast cancer mortality in randomized controlled trials (RCTs). We sought to evaluate the effectiveness of mammography screening in women aged 39-49 years in reducing breast cancer mortality and to discuss previously published meta-analyses.
  
  
  METHODS
  PubMed/MEDLINE, OVID, COCHRANE, and Educational Resources Information Center (ERIC) databases were searched, and extracted references were reviewed. Dissertation abstracts and clinical trials databases available online were assessed to identify unpublished works. All assessments were independently done by two reviewers. All trials included were RCTs, published in English, included data on women aged 39-49, and reported relative risk (RR)/odds ratio (OR) or frequency data.
  
  
  RESULTS
  Nine studies were identified: the Kopparberg, Ostergotland (The Two-County study), Health Insurance Plan (HIP), Canada, Stockholm, Gothenburg, Edinburgh, Age, and Malmo trials. The individual trials were quality assessed, and the data were extracted using predefined forms. Using the DerSimonian and Laird random effects model, the results from the seven RCTs with the highest quality score were combined, and a significant pooled RR estimate of 0.83 (95% confidence interval [CI] 0.72-0.97) was calculated. Post hoc sensitivity analyses excluding studies with randomization before 1980 caused a loss of statistical significance (RR 0.87, 95% CI: 0.56, 1.13).
  
  
  CONCLUSIONS
  Mammography screenings are effective and generate a 17% reduction in breast cancer mortality in women 39-49 years of age. The quality of the trials varies, and providers should inform women in this age group about the positive and negative aspects of mammography screenings.
authors.affiliation: Department of Epidemiology, Tulane School of Public Health and Tropical Medicine, 1440 Canal Street, New Orleans, LA 70112, USA. jmagnus@tulane.edu
authors.forename: Maria C
authors.initials: MC
authors.lastname: Magnus
authors.forename: Ma
authors.initials: M
authors.lastname: Ping
authors.forename: Miao Miao
authors.initials: MM
authors.lastname: Shen
authors.forename: John
authors.initials: J
authors.lastname: Bourgeois
authors.forename: Jeanette H
authors.initials: JH
authors.lastname: Magnus
mesh_terms: D000328:Adult; D000367:Age Factors; D001007:Anxiety; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000401:mortality*; D055088:Early Detection of Cancer / Q000379:methods; D005260:Female; D006801:Humans; D008327:Mammography / Q000009:adverse effects / Q000523:psychology; D008875:Middle Aged; D016032:Randomized Controlled Trials as Topic; D012680:Sensitivity and Specificity