title: Tanning bed use is not associated with internal cancer risk: evidence from a large cohort study.
abstract: BACKGROUND
  Increased risk of skin cancer by indoor tanning has drawn public attention. However, there are arguments that tanning bed use increases vitamin D production, which may therefore prevent internal cancers.
  
  
  METHODS
  We followed 73,358 female nurses for 20 years (1989-2009) in the Nurses' Health Study II and investigated the frequency of tanning bed use during high school/college and at ages 25 to 35 in relation to the incidence of total cancers (excluding skin cancers). We used multivariate Cox proportional hazards models to estimate the HRs and 95% confidence intervals (CI) of total cancers and each individual major cancer with more than 100 cases.
  
  
  RESULTS
  During follow-up, a total of 4,271 internal cancer-related cases were diagnosed. No association was found between tanning bed use and risk of total cancers (multivariable-adjusted HR, 0.99; 95% CI, 0.95-1.04 for every 4 times/y use on average during high school/college and at ages 25-35). In addition, no association was found for the risk of any individual major cancers, such as breast cancer, thyroid cancer, colorectal cancer, non-Hodgkin lymphoma, or endometrial cancer.
  
  
  CONCLUSIONS
  Our data do not suggest any association between the use of tanning beds and risk of internal cancers.
  
  
  CONCLUSIONS
  On the basis of the strong evidence of increase in skin cancer risk and no evidence of reduction in internal cancer risk by tanning bed use, it is important to warn the public against indoor tanning.
authors.affiliation: Authors' Affiliations: Clinical Research Program, Department of Dermatology; Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School; Departments of Nutrition, Epidemiology, and the Program in Genetic Epidemiology and Statistical Genetics, Harvard School of Public Health, Boston, Massachusetts; Department of Epidemiology, Richard M. Fairbanks School of Public Health, Simon Cancer Center, Indiana University, Indianapolis, Indiana; and Department of Epidemiology, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China.
authors.forename: Mingfeng
authors.initials: M
authors.lastname: Zhang
authors.forename: Fengju
authors.initials: F
authors.lastname: Song
authors.forename: David J
authors.initials: DJ
authors.lastname: Hunter
authors.forename: Abrar A
authors.initials: AA
authors.lastname: Qureshi
authors.forename: Jiali
authors.initials: J
authors.lastname: Han
mesh_terms: D000328:Adult; D001505:Beauty Culture / Q000295:instrumentation* / Q000706:statistics & numerical data*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology* / Q000209:etiology; D012307:Risk Factors; D012878:Skin Neoplasms / Q000453:epidemiology* / Q000209:etiology; D055108:Sunbathing; D011795:Surveys and Questionnaires; D014466:Ultraviolet Rays; D014481:United States / Q000453:epidemiology