title: Prospective study of UV exposure and cancer incidence among Swedish women.
abstract: BACKGROUND
  Except for skin melanoma and nonmelanoma skin cancer, little evidence from prospective studies is available on the association between UV exposure and cancer risk.
  
  
  METHODS
  We followed prospectively 49,261 women aged 30 to 49 years at enrollment in 1991 to 1992 for 15 years. Cancer incidence was analyzed by fitting Cox models, and estimating hazard ratios (HR) and 95% confidence intervals (CI).
  
  
  RESULTS
  2,303 incident cases of cancer were diagnosed (breast: 1,053, ovary: 126, lung: 116, colon-rectum: 133, and brain: 116). No associations were found between any cumulative measure of UV exposure at ages 10 to 39 years and overall cancer risk. However, spending ≥1 week/year between ages 10 and 29 years on sunbathing vacations led to an inverse association with overall cancer risk (HR: 0.70, 95% CI: 0.53-0.93) and breast cancer risk (HR: 0.56, 95% CI: 0.36-0.89) when compared with women who never went on such vacations. Solarium use was inversely associated with breast cancer risk, whereas ≥2 sunburns/year was inversely associated with lung cancer risk. No other associations were found between sun exposure or solarium use at ages 10 to 39 years and cancer risk.
  
  
  CONCLUSIONS
  We found no evidence of an association between any cumulative measure of UV exposure at ages 10 to 39 years and overall cancer risk. UV exposure earlier in life was related to reduced overall and breast cancer risk.
  
  
  CONCLUSIONS
  Further research is needed to define the amount of solar or artificial UV exposure that may, or may not, be beneficial for cancer prevention.
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Ling
authors.initials: L
authors.lastname: Yang
authors.forename: Marit B
authors.initials: MB
authors.lastname: Veierød
authors.forename: Marie
authors.initials: M
authors.lastname: Löf
authors.forename: Sven
authors.initials: S
authors.lastname: Sandin
authors.forename: Hans-Olov
authors.initials: HO
authors.lastname: Adami
authors.forename: Elisabete
authors.initials: E
authors.lastname: Weiderpass
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D005260:Female; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009369:Neoplasms / Q000453:epidemiology* / Q000209:etiology*; D016016:Proportional Hazards Models; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013548:Sweden / Q000453:epidemiology; D014466:Ultraviolet Rays / Q000009:adverse effects*; D055815:Young Adult