title: Physical activity and body mass index as predictors of prostate cancer risk.
abstract: OBJECTIVE
  Physical activity and body mass index (BMI) are involved in prostate cancer etiology; possible biologic mechanisms include their effects on hormonal levels. Our aim was to investigate the relationship between physical activity, obesity, and prostate cancer.
  
  
  METHODS
  We followed a cohort of 13,109 Swedish men for 13 years and investigated the association of self-reported physical activity and BMI at baseline with prostate cancer incidence. We further analyzed whether BMI could modulate effects of physical activity. Occupational, recreational, and total physical activity were analyzed in relation to overall, localized, and advanced prostate cancer.
  
  
  RESULTS
  During the study follow-up, we observed a total of 904 cases of prostate cancer (429 localized, 407 advanced, and 68 unclassified). High levels of occupational physical activity were associated with a nonsignificantly decreased risk of overall (HR 0.81, 95 % CI 0.61-1.07), localized (HR 0.75, 95 % CI 0.51-1.12), and advanced (HR 0.85, 95 % CI 0.55-1.31) prostate cancer. We found no association between high BMI and risk of prostate cancer incidence: We observed, however, a significant interaction between BMI and leisure physical activity.
  
  
  CONCLUSIONS
  No association was confirmed between total physical activity and localized or advanced prostate cancer. The highest, relative to the lowest, level of occupational physical activity tended to be linked to a lower risk of prostate cancer, with a suggested dose-response relationship. We found no association between high BMI and risk of prostate cancer incidence; however, our analyses suggested an interaction between BMI and physical activity during recreational time that merits further investigation in future studies.
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Box 281, 171 77, Stockholm, Sweden. alessandra.grotta@ki.se.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Grotta
authors.affiliation: Institute of Environmental Medicine, Karolinska Institutet, Box 210, 171 77, Stockholm, Sweden. matteo.bottai@ki.se.
authors.forename: Matteo
authors.initials: M
authors.lastname: Bottai
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Box 281, 171 77, Stockholm, Sweden. hadami@hsph.harvard.edu.|Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA. hadami@hsph.harvard.edu.
authors.forename: Hans-Olov
authors.initials: HO
authors.lastname: Adami
authors.affiliation: Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, Columbia, SC, USA. swann.adams@sc.edu.|Statewide Cancer Prevention and Control Program, University of South Carolina, Columbia, SC, USA. swann.adams@sc.edu.
authors.forename: Swann Arp
authors.initials: SA
authors.lastname: Adams
authors.affiliation: Department of Medicine, Karolinska Institutet, Solna, Sweden. olof.akre@ki.se.
authors.forename: Olof
authors.initials: O
authors.lastname: Akre
authors.affiliation: Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, Columbia, SC, USA. sblair@mailbox.sc.edu.|Department of Exercise Science, Arnold School of Public Health, University of South Carolina, Columbia, SC, USA. sblair@mailbox.sc.edu.
authors.forename: Steven Noel
authors.initials: SN
authors.lastname: Blair
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Box 281, 171 77, Stockholm, Sweden. daniela.mariosa@ki.se.
authors.forename: Daniela
authors.initials: D
authors.lastname: Mariosa
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Box 281, 171 77, Stockholm, Sweden. olof.nyren@ki.se.
authors.forename: Olof
authors.initials: O
authors.lastname: Nyrén
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Box 281, 171 77, Stockholm, Sweden. weimin.ye@ki.se.
authors.forename: Weimin
authors.initials: W
authors.lastname: Ye
authors.affiliation: Surgery and Perioperative Sciences, Urology and Andrology, Umeå University Hospital, Umeå, Sweden. par.stattin@umu.se.
authors.forename: Pär
authors.initials: P
authors.lastname: Stattin
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Box 281, 171 77, Stockholm, Sweden. rino.bellocco@ki.se.|Department of Statistics and Quantitative Methods, University of Milano-Bicocca, Milan, Italy. rino.bellocco@ki.se.
authors.forename: Rino
authors.initials: R
authors.lastname: Bellocco
authors.affiliation: Unit of Clinical Epidemiology, Department of Medicine, Karolinska Institutet, Solna, Sweden. ylva.trolle@ki.se.
authors.forename: Ylva
authors.initials: Y
authors.lastname: Trolle Lagerros
mesh_terms: D015992:Body Mass Index; D005500:Follow-Up Studies; D005544:Forecasting; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D009765:Obesity / Q000453:epidemiology* / Q000503:physiopathology; D011471:Prostatic Neoplasms / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology*; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013548:Sweden / Q000453:epidemiology
keywords: Body mass index; Cohort study; Epidemiology; Physical activity; Prostate cancer