title: Presentation on websites of possible benefits and harms from screening for breast cancer: cross sectional study.
abstract: OBJECTIVE
  To investigate whether information on mammographic screening presented on websites by interest groups is balanced, is independent of source of funding, and reflects recent findings.
  
  
  METHODS
  Cross sectional study using a checklist with 17 information items.
  
  
  METHODS
  27 websites in Scandinavian and English speaking countries.
  
  
  RESULTS
  The 13 sites from advocacy groups and the 11 from governmental institutions all recommended mammographic screening, whereas the three from consumer organisations questioned screening (P = 0.0007). All the advocacy groups accepted industry funding, apparently without restrictions. In contrast the three consumer organisations acknowledged the risk of bias related to industry funding, and two of them did not accept such funding at all. Advocacy groups and governmental organisations favoured information items that shed positive light on screening. The major harms of screening, overdiagnosis and overtreatment, were mentioned by only four of these groups, but by all three sites from consumer organisations (P = 0.02). In addition, the chosen information was often misleading or erroneous. The selection of information items for websites did not reflect recent findings, apart from the consumer sites, which were much more balanced and comprehensive than other sites (median of 9 information items v 3 items, P = 0.03).
  
  
  CONCLUSIONS
  The information material provided by professional advocacy groups and governmental organisations is information poor and severely biased in favour of screening. Few websites live up to accepted standards for informed consent such as those stated in the General Medical Council's guidelines.
authors.affiliation: Nordic Cochrane Centre, H:S Rigshospitalet, DK-2100 København Ø, Denmark.
authors.forename: Karsten Juhl
authors.initials: KJ
authors.lastname: Jørgensen
authors.forename: Peter C
authors.initials: PC
authors.lastname: Gøtzsche
mesh_terms: D015982:Bias; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D003430:Cross-Sectional Studies; D003627:Data Interpretation, Statistical; D003951:Diagnostic Errors; D005260:Female; D006266:Health Education; D006801:Humans; D033181:Information Dissemination; D020407:Internet; D008327:Mammography; D008403:Mass Screening; D008490:Medical Informatics / Q000592:standards*; D018570:Risk Assessment; D012307:Risk Factors