title: Sedentary work and the risk of breast cancer in premenopausal and postmenopausal women: a pooled analysis of two case-control studies.
abstract: OBJECTIVE
  There is limited research on the association between sedentary behaviour and breast cancer risk, particularly whether sedentary behaviour is differentially associated with premenopausal and postmenopausal breast cancer. We pooled data from 2 case-control studies from Australia and Canada to investigate this association.
  
  
  METHODS
  This pooled analysis included 1762 incident breast cancer cases and 2532 controls. Participants in both studies completed a lifetime occupational history and self-rated occupational physical activity level. A job-exposure matrix (JEM) was also applied to job titles to assess sedentary work. Logistic regression analyses (6 pooled and 12 study-specific) were conducted to estimate associations between both self-reported and JEM-assessed sedentary work and breast cancer risk among premenopausal and postmenopausal women.
  
  
  RESULTS
  No association was observed in the 6 pooled analyses, and 10 of the study-specific analyses also showed null results. 2 study-specific analyses provided inconsistent and contradictory results, with 1 showing statistically significant increased risk of breast cancer for self-reported sedentary work among premenopausal women cancer in the Canadian study, and the other a non-significant inverse association between JEM-assessed sedentary work and breast cancer risk among postmenopausal women in the Australian study.
  
  
  CONCLUSIONS
  While a suggestion of increased risk was seen for premenopausal women in the Canadian study when using the self-reported measure, overall this pooled study does not provide evidence that sedentary work is associated with breast cancer risk.
authors.affiliation: Cancer Control Research, British Columbia Cancer Agency, Vancouver, British Columbia, Canada School of Population and Public Health, The University of British Columbia, Vancouver, British Columbia, Canada Centre for Medical Research, The University of Western Australia, Perth, Western Australia, Australia School of Public Health, Curtin University, Perth, Western Australia, Australia.
authors.forename: Terry
authors.initials: T
authors.lastname: Boyle
authors.affiliation: School of Public Health, Curtin University, Perth, Western Australia, Australia.
authors.forename: Lin
authors.initials: L
authors.lastname: Fritschi
authors.affiliation: Department of Epidemiology and Public Health, University College London, London, UK Department of Public Health Sciences, Queen's University, Kingston, Ontario, Canada Division of Cancer Care and Epidemiology, Cancer Research Institute, Queen's University, Kingston, Ontario, Canada.
authors.forename: Lindsay C
authors.initials: LC
authors.lastname: Kobayashi
authors.affiliation: School of Population Health, The University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Jane S
authors.initials: JS
authors.lastname: Heyworth
authors.affiliation: Cancer Control Research, British Columbia Cancer Agency, Vancouver, British Columbia, Canada School of Population and Public Health, The University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Derrick G
authors.initials: DG
authors.lastname: Lee
authors.affiliation: School of Public Health, Curtin University, Perth, Western Australia, Australia.
authors.forename: Si
authors.initials: S
authors.lastname: Si
authors.affiliation: Department of Public Health Sciences, Queen's University, Kingston, Ontario, Canada Division of Cancer Care and Epidemiology, Cancer Research Institute, Queen's University, Kingston, Ontario, Canada.
authors.forename: Kristan J
authors.initials: KJ
authors.lastname: Aronson
authors.affiliation: Cancer Control Research, British Columbia Cancer Agency, Vancouver, British Columbia, Canada.
authors.forename: John J
authors.initials: JJ
authors.lastname: Spinelli
mesh_terms: D000328:Adult; D000368:Aged; D001315:Australia / Q000453:epidemiology; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000209:etiology*; D002170:Canada / Q000453:epidemiology; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008875:Middle Aged; D009790:Occupations; D017698:Postmenopause; D017697:Premenopause; D012307:Risk Factors; D057185:Sedentary Behavior; D011795:Surveys and Questionnaires; D014937:Work
keywords: breast cancer; job-exposure matrix; sedentary work