title: Perceived physical strain at work and incidence of colorectal cancer: A nested case-control study.
abstract: The evidence for a relationship between colon cancer incidence and physical activity is not fully convincing, and the association between physical activity and rectal cancer is also unclear. We studied the association between perceived physical workload (PPWL) at work and colorectal cancer, stratified by subsite, in a nested case-control setting in the Nordic Occupational Cancer (NOCCA) data from Finland, Iceland, Norway and Sweden. Five population controls were selected for each cancer patient. PPWL showed a bigger protective effect on colon cancer for males (odds ratio [OR] 0.74 in the highest PPWL decile as compared with the lowest PPWL category, 95% confidence interval [95% CI]: 0.72-0.77) than for females (OR 0.87, 95% CI: 0.81-0.95), with a significant trend for different levels of PPWL for both males and females. In males, the OR of cancer in the descending colon for the highest PPWL decile of males was 0.61 (95% CI: 0.54-0.69). For females the protective effect was most notable in the transversal part of the colon (OR 0.83, 95% CI: 0.67-1.03). The OR for rectal cancer in the highest PPWL decile for males was 0.87 (95% CI: 0.85-0.90) and for females 0.93 (95% CI: 0.83-1.04). Inclusion of further agents in multivariate analyses did not alter the ORs for PPWL. The incidence of colon cancer and, to a lesser extent, rectal cancer is lowest in professions with the highest PPWL. The association is clearer in males than in females. The biggest protective effect appears to be in the descending colon in males.
authors.affiliation: School of Health Sciences, University of Tampere, Tampere, Finland; Tampere University Hospital, Lahti Unit of Radiation Therapy, Lahti, Finland. Electronic address: Jorma.Sormunen@gmail.com.
authors.forename: Jorma
authors.initials: J
authors.lastname: Sormunen
authors.affiliation: School of Health Sciences, University of Tampere, Tampere, Finland.
authors.forename: Madar
authors.initials: M
authors.lastname: Talibov
authors.affiliation: Department of Research, Cancer Registry of Norway, Institute of Population-Based Cancer Research, Oslo, Norway.
authors.forename: Jan Ivar
authors.initials: JI
authors.lastname: Martinsen
authors.affiliation: Department of Research, Cancer Registry of Norway, Institute of Population-Based Cancer Research, Oslo, Norway.
authors.forename: Kristina
authors.initials: K
authors.lastname: Kjaerheim
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Pär
authors.initials: P
authors.lastname: Sparen
authors.affiliation: Icelandic Cancer Registry, Reykjavik, Iceland; Faculty of Medicine, University of Iceland, Reykjavik, Iceland.
authors.forename: Laufey
authors.initials: L
authors.lastname: Tryggvadottir
authors.affiliation: Department of Research, Cancer Registry of Norway, Institute of Population-Based Cancer Research, Oslo, Norway; Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden; Genetic Epidemiology Group, Folkhälsan Research Center, Helsinki, Finland; Department of Community Medicine, University of Tromsø, The Arctic University of Norway, Tromsø, Norway.
authors.forename: Elisabete
authors.initials: E
authors.lastname: Weiderpass
authors.affiliation: School of Health Sciences, University of Tampere, Tampere, Finland; Finnish Cancer Registry, Institute for Statistical and Epidemiological Cancer Research, Helsinki, Finland.
authors.forename: Eero
authors.initials: E
authors.lastname: Pukkala
mesh_terms: D016022:Case-Control Studies; D003110:Colonic Neoplasms / Q000453:epidemiology*; D015179:Colorectal Neoplasms / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D012004:Rectal Neoplasms / Q000453:epidemiology; D012307:Risk Factors
keywords: Colon cancer; Epidemiology; Physical workload