title: Indoor tanning and non-melanoma skin cancer: systematic review and meta-analysis.
abstract: OBJECTIVE
  To synthesise the literature on indoor tanning and non-melanoma skin cancer.
  
  
  METHODS
  Systematic review and meta-analysis.
  
  
  METHODS
  PubMed (1966 to present), Embase (1974 to present), and Web of Science (1898 to present).
  
  
  METHODS
  All articles that reported an original effect statistic for indoor tanning and non-melanoma skin cancer were included. Articles that presented no data, such as review articles and editorials, were excluded, as were articles in languages other than English.
  
  
  METHODS
  Two investigators independently extracted data. Random effects meta-analysis was used to summarise the relative risk of ever use versus never use of indoor tanning. Dose-response effects and exposure to indoor tanning during early life were also examined. The population attributable risk fraction for the United States population was calculated.
  
  
  RESULTS
  12 studies with 9328 cases of non-melanoma skin cancer were included. Among people who reported ever using indoor tanning compared with those who never used indoor tanning, the summary relative risk for squamous cell carcinoma was 1.67 (95% confidence interval 1.29 to 2.17) and that for basal cell carcinoma was 1.29 (1.08 to 1.53). No significant heterogeneity existed between studies. The population attributable risk fraction for the United States was estimated to be 8.2% for squamous cell carcinoma and 3.7% for basal cell carcinoma. This corresponds to more than 170 000 cases of non-melanoma skin cancer each year attributable to indoor tanning. On the basis of data from three studies, use of indoor tanning before age 25 was more strongly associated with both squamous cell carcinoma (relative risk 2.02, 0.70 to 5.86) and basal cell carcinoma (1.40, 1.29 to 1.52).
  
  
  CONCLUSIONS
  Indoor tanning is associated with a significantly increased risk of both basal and squamous cell skin cancer. The risk is higher with use in early life (<25 years). This modifiable risk factor may account for hundreds of thousands of cases of non-melanoma skin cancer each year in the United States alone and many more worldwide. These findings contribute to the growing body of evidence on the harms of indoor tanning and support public health campaigns and regulation to reduce exposure to this carcinogen.
authors.affiliation: Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Mackenzie R
authors.initials: MR
authors.lastname: Wehner
authors.forename: Melissa L
authors.initials: ML
authors.lastname: Shive
authors.forename: Mary-Margaret
authors.initials: MM
authors.lastname: Chren
authors.forename: Jiali
authors.initials: J
authors.lastname: Han
authors.forename: Abrar A
authors.initials: AA
authors.lastname: Qureshi
authors.forename: Eleni
authors.initials: E
authors.lastname: Linos
mesh_terms: D002280:Basal Cell Carcinoma / Q000453:epidemiology* / Q000209:etiology*; D002294:Carcinoma, Squamous Cell / Q000453:epidemiology* / Q000209:etiology*; D003430:Cross-Sectional Studies; D006801:Humans; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology* / Q000209:etiology*; D016017:Odds Ratio; D016016:Proportional Hazards Models; D012878:Skin Neoplasms / Q000453:epidemiology* / Q000209:etiology*; D055108:Sunbathing / Q000706:statistics & numerical data*; D014466:Ultraviolet Rays / Q000009:adverse effects*