title: Long working hours and cancer risk: a multi-cohort study.
abstract: BACKGROUND
  Working longer than the maximum recommended hours is associated with an increased risk of cardiovascular disease, but the relationship of excess working hours with incident cancer is unclear.
  
  
  METHODS
  This multi-cohort study examined the association between working hours and cancer risk in 116 462 men and women who were free of cancer at baseline. Incident cancers were ascertained from national cancer, hospitalisation and death registers; weekly working hours were self-reported.
  
  
  RESULTS
  During median follow-up of 10.8 years, 4371 participants developed cancer (n colorectal cancer: 393; n lung cancer: 247; n breast cancer: 833; and n prostate cancer: 534). We found no clear evidence for an association between working hours and the overall cancer risk. Working hours were also unrelated the risk of incident colorectal, lung or prostate cancers. Working ⩾55 h per week was associated with 1.60-fold (95% confidence interval 1.12-2.29) increase in female breast cancer risk independently of age, socioeconomic position, shift- and night-time work and lifestyle factors, but this observation may have been influenced by residual confounding from parity.
  
  
  CONCLUSIONS
  Our findings suggest that working long hours is unrelated to the overall cancer risk or the risk of lung, colorectal or prostate cancers. The observed association with breast cancer would warrant further research.
authors.affiliation: Department of Health Services Research and Policy, London School of Hygiene and Tropical Medicine, London WC1H 9SH, UK.|Finnish Institute of Occupational Health, 33100 Tampere and 205200 Turku, Helsinki 0250, Finland.
authors.forename: Katriina
authors.initials: K
authors.lastname: Heikkila
authors.affiliation: Finnish Institute of Occupational Health, 33100 Tampere and 205200 Turku, Helsinki 0250, Finland.
authors.forename: Solja T
authors.initials: ST
authors.lastname: Nyberg
authors.affiliation: National Research Centre for the Working Environment, Copenhagen DK-2100, Denmark.
authors.forename: Ida E H
authors.initials: IE
authors.lastname: Madsen
authors.affiliation: TNO, Leiden 2316 ZL, The Netherlands.
authors.forename: Ernest
authors.initials: E
authors.lastname: de Vroome
authors.affiliation: Centre for Occupational and Environmental Medicine, Stockholm County Council, Sweden.|Institute of Environmental Medicine, Karolinska Institutet, Stockholm 171 77, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Alfredsson
authors.affiliation: National Research Centre for the Working Environment, Copenhagen DK-2100, Denmark.
authors.forename: Jacob J
authors.initials: JJ
authors.lastname: Bjorner
authors.affiliation: Køge Hospital, Køge 4600, Denmark.
authors.forename: Marianne
authors.initials: M
authors.lastname: Borritz
authors.affiliation: Federal Institute for Occupational Safety and Health, Berlin 10317, Germany.
authors.forename: Hermann
authors.initials: H
authors.lastname: Burr
authors.affiliation: Department of Cardiology, West-German Heart Center Essen, University Duisburg-Essen, Essen 45122, Germany.
authors.forename: Raimund
authors.initials: R
authors.lastname: Erbel
authors.affiliation: Department of Epidemiology and Public Health, University College London, London WC1E 6BT, UK.|School of Social and Community Medicine, University of Bristol, Bristol BS8 2PS, UK.
authors.forename: Jane E
authors.initials: JE
authors.lastname: Ferrie
authors.affiliation: Institute of Environmental Medicine, Karolinska Institutet, Stockholm 171 77, Sweden.|School of Health and Welfare, Jönköping University, SE-551 11 Jönköping, Sweden.|Stress Research Institute, Stockholm University, Stockholm SE-106 91, Sweden.
authors.forename: Eleonor I
authors.initials: EI
authors.lastname: Fransson
authors.affiliation: TNO, Leiden 2316 ZL, The Netherlands.
authors.forename: Goedele A
authors.initials: GA
authors.lastname: Geuskens
authors.affiliation: TNO, Leiden 2316 ZL, The Netherlands.
authors.forename: Wendela E
authors.initials: WE
authors.lastname: Hooftman
authors.affiliation: TNO, Leiden 2316 ZL, The Netherlands.
authors.forename: Irene L
authors.initials: IL
authors.lastname: Houtman
authors.affiliation: Institute for Medical Informatics, Biometry and Epidemiology, Faculty of Medicine, University Duisburg-Essen, Essen 45122, Germany.
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Jöckel
authors.affiliation: Department of Health Sciences, Mid Sweden University, Sundsvall 851 70, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Knutsson
authors.affiliation: Department of Public Health, University of Helsinki, Helsinki 00140, Finland.
authors.forename: Markku
authors.initials: M
authors.lastname: Koskenvuo
authors.affiliation: Institute for Medical Sociology, Medical Faculty, University of Düsseldorf, Düsseldorf 40225, Germany.
authors.forename: Thorsten
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authors.lastname: Lunau
authors.affiliation: Unit of Social Medicine, Frederiksberg University Hospital, Fredriksberg 2000, Denmark.
authors.forename: Martin L
authors.initials: ML
authors.lastname: Nielsen
authors.affiliation: Stress Research Institute, Stockholm University, Stockholm SE-106 91, Sweden.|Department of Psychology, Umeå University, Umeå 901 87, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Nordin
authors.affiliation: Finnish Institute of Occupational Health, 33100 Tampere and 205200 Turku, Helsinki 0250, Finland.
authors.forename: Tuula
authors.initials: T
authors.lastname: Oksanen
authors.affiliation: The Danish National Centre for Social Research, Copenhagen 1052, Denmark.
authors.forename: Jan H
authors.initials: JH
authors.lastname: Pejtersen
authors.affiliation: Finnish Institute of Occupational Health, 33100 Tampere and 205200 Turku, Helsinki 0250, Finland.
authors.forename: Jaana
authors.initials: J
authors.lastname: Pentti
authors.affiliation: Department of Epidemiology and Public Health, University College London, London WC1E 6BT, UK.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Shipley
authors.affiliation: Department of Epidemiology and Public Health, University College London, London WC1E 6BT, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Steptoe
authors.affiliation: Department of Public Health, University of Turku, Turku 20014, Finland.|Folkhälsan Research Center, Helsinki 00290, Finland.|Nordic School of Public Health, Göteborg 426 71, Sweden.
authors.forename: Sakari B
authors.initials: SB
authors.lastname: Suominen
authors.affiliation: Stress Research Institute, Stockholm University, Stockholm SE-106 91, Sweden.
authors.forename: Töres
authors.initials: T
authors.lastname: Theorell
authors.affiliation: Finnish Institute of Occupational Health, 33100 Tampere and 205200 Turku, Helsinki 0250, Finland.|Department of Public Health, University of Turku, Turku 20014, Finland.|Turku University Hospital, Turku 20521, Finland.
authors.forename: Jussi
authors.initials: J
authors.lastname: Vahtera
authors.affiliation: Occupational and Environmental Medicine, Uppsala University, Uppsala 751 85, Sweden.
authors.forename: Peter J M
authors.initials: PJ
authors.lastname: Westerholm
authors.affiliation: Stress Research Institute, Stockholm University, Stockholm SE-106 91, Sweden.
authors.forename: Hugo
authors.initials: H
authors.lastname: Westerlund
authors.affiliation: Institute for Medical Sociology, Medical Faculty, University of Düsseldorf, Düsseldorf 40225, Germany.
authors.forename: Nico
authors.initials: N
authors.lastname: Dragano
authors.affiliation: National Research Centre for the Working Environment, Copenhagen DK-2100, Denmark.|Department of Public Health and Department of Psychology, University of Copenhagen, Copenhagen 2200, Denmark.
authors.forename: Reiner
authors.initials: R
authors.lastname: Rugulies
authors.affiliation: Department of Society, Human Development and Health, Harvard School of Public Health, Boston, Massachusetts 02115, USA.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Kawachi
authors.affiliation: Department of Epidemiology and Public Health, University College London, London WC1E 6BT, UK.|Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh EH8 9JZ, UK.
authors.forename: G David
authors.initials: GD
authors.lastname: Batty
authors.affiliation: Department of Epidemiology and Public Health, University College London, London WC1E 6BT, UK.|Inserm U1018, Centre for Research in Epidemiology and Population Health, Villejuif 94807, France.
authors.forename: Archana
authors.initials: A
authors.lastname: Singh-Manoux
authors.affiliation: Finnish Institute of Occupational Health, 33100 Tampere and 205200 Turku, Helsinki 0250, Finland.
authors.forename: Marianna
authors.initials: M
authors.lastname: Virtanen
authors.affiliation: Finnish Institute of Occupational Health, 33100 Tampere and 205200 Turku, Helsinki 0250, Finland.|Department of Epidemiology and Public Health, University College London, London WC1E 6BT, UK.|Clinicum, Faculty of Medicine, University of Helsinki, Helsinki FI-00014, Finland.
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mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000453:epidemiology / Q000209:etiology*; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors; D012959:Socioeconomic Factors; D013997:Time Factors; D014940:Work Schedule Tolerance; D055815:Young Adult