title: Cancer incidence in participants in a long-distance ski race (Vasaloppet, Sweden) compared to the background population.
abstract: BACKGROUND
  We studied the association between taking part in a long distance ski race and cancer incidence to address the hypothesis that a lifestyle involving a high degree of physical activity (PA) lowers cancer incidence with a pattern that is different by cancer site.
  
  
  METHODS
  Cancer incidence was estimated in a large cohort of skiers (n=185,412) participating in the Vasaloppet long distance ski race in Sweden 1989-2010 and non-participants in the ski race, randomly selected from the Swedish general population (n=184,617). Data include race finishing times as a measurement of physical fitness. Hazard ratios (HRs) and net probability of cancer over twenty years of follow-up were estimated for all invasive cancer, and separately for prostate, breast, colo-rectal and lung cancer, and groups of cancers with presumed relation to lifestyle.
  
  
  RESULTS
  Participating in Vasaloppet was associated with a relative risk reduction for all invasive cancer of 6% (95% confidence interval 2-9%) and a relative risk reduction of 32% (95% confidence interval 28-37%) of cancer sites where there is epidemiological evidence that smoking, bodyweight, regular PA and consumption of fruit and vegetables are aetiological factors. For skin cancer the risk was increased, as for prostate cancer. Skiers with shorter finishing times had lower incidence of cancer.
  
  
  CONCLUSIONS
  This study indicates that it is unrealistic to reduce overall population cancer incidence drastically with life style. However, cancers that are epidemiologically associated with life style factors were significantly reduced by what presumably is a blend of non-smoking, normal body weight, sound dietary habits and PA. Our data thus provide additional support for present days' recommendations about life style prevention. Higher health awareness is associated with attendance to screening, which may explain our results for prostate cancer.
  
  
  BACKGROUND
  University fund, independent funds from an insurance company and a private foundation.
authors: Department of Medical Sciences Uppsala University, Uppsala, Sweden; Department of Internal Medicine, Mora Hospital, Mora, Sweden. Electronic address: ulf.hallmarker@ltdalarna.se.
authors: Ulf
authors: U
authors: Hållmarker
authors: Department of Medical Sciences Uppsala University, Uppsala, Sweden; Uppsala Clinical Research Center, Uppsala, Sweden.
authors: Stefan
authors: S
authors: James
authors: Department of Surgical Sciences Uppsala University, Uppsala, Sweden; Uppsala Clinical Research Center, Uppsala, Sweden.
authors: Karl
authors: K
authors: Michaëlsson
authors: Department of Medical Sciences Uppsala University, Uppsala, Sweden; School of Health and Social Studies, Dalarna University, Falun, Sweden.
authors: Johan
authors: J
authors: Ärnlöv
authors: Regional Cancer Center Uppsala-Örebro, Uppsala, Sweden.
authors: Fredrik
authors: F
authors: Sandin
authors: Department of Surgical Sciences Uppsala University, Uppsala, Sweden; Regional Cancer Center Uppsala-Örebro, Uppsala, Sweden; King's College London, Faculty of Life Sciences & Medicine, London, UK.
authors: Lars
authors: L
authors: Holmberg
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D015994:Incidence; D008019:Life Style; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000453:epidemiology*; D013177:Sports; D013548:Sweden / Q000453:epidemiology; D013997:Time Factors
keywords: Cross county skiing; Epidemiology; Exercise; Life style; Neoplasms; Physical fitness; Public health; Sports medicine