title: Assessing the internet prevalence of cancer.
abstract: BACKGROUND
  The internet is one of the most frequently accessed sources of information by patients. There is a variety of cancer-related information provided by the internet, aimed at both the general public (from official sites and non-regulated sites) and health care professionals. Little is known about whether the information provided reflects the prevalence of disease.
  
  
  METHODS
  Searches for the 10 most common UK cancers were performed using five internet search engines. The number of relevant webpages was recorded and compared to the prevalence of each cancer according to Cancer Research UK.
  
  
  RESULTS
  Of the 985,687,623 webpages identified, the majority were related to breast cancer (37.2%), followed by lung (16.2%) and prostate cancer (12.5%). Colorectal cancer, Oesophageal cancer and non-Hodgkin's lymphoma had the least number of websites (4.1%, 0.3% and 0.9%, respectively). There was over-representation of breast, kidney and stomach cancer with ratios of prevalence to number of websites of 1.7, 2.6 and 2.5 to 1, respectively. There was under-representation of colorectal cancer, non-Hodgkin's lymphoma and oesophageal cancer (ratios 0.2, 0.2 and 0.1, respectively).
  
  
  CONCLUSIONS
  This data highlights the enormity of information available on the internet. However, there is over-representation of certain cancers (and under-representation of others) which may influence how patients perceive their illness. Healthcare professionals should be aware of the nature of information available on the internet and known when and how to direct patients to reputable sites that provide high quality information.
authors.affiliation: Department of Surgery, The Great Western Hospital, Swindon, UK. jmlw@doctors.org.uk
authors.forename: J M L
authors.initials: JM
authors.lastname: Williamson
authors.forename: D B
authors.initials: DB
authors.lastname: Hocken
mesh_terms: D003625:Data Collection; D006801:Humans; D020407:Internet / Q000706:statistics & numerical data*; D009369:Neoplasms / Q000453:epidemiology*; D015995:Prevalence; D057386:Search Engine / Q000706:statistics & numerical data; D006113:United Kingdom / Q000453:epidemiology