title: Change in weight and waist circumference and risk of colorectal cancer: results from the Melbourne Collaborative Cohort Study.
abstract: BACKGROUND
  Studies reporting the association between change in weight or body mass index during midlife and risk of colorectal cancer have found inconsistent results, and only one study to date has reported the association between change in waist circumference (a measure of central adiposity) and risk of colorectal cancer.
  
  
  METHODS
  We investigated the association between risk of colorectal cancer and changes in directly measured waist circumference and weight from baseline (1990-1994) to wave 2 (2003-2007). Cox regression, with age as the time metric and follow-up starting at wave 2, adjusted for covariates selected from a causal model, was used to estimate the Hazard Ratios (HRs) and 95 % Confidence Intervals (CIs) for the change in waist circumference and weight in relation to risk of colorectal cancer.
  
  
  RESULTS
  A total of 373 cases of colorectal cancer were diagnosed during an average 9 years of follow-up of 20,605 participants. Increases in waist circumference and weight were not associated with the risk of colorectal cancer (HR per 5 cm increase in waist circumference = 1.02; 95 % CI: 0.95, 1.10; HR per 5 kg increase in weight = 0.93; 0.85, 1.02). For individuals with a waist circumference at baseline that was less than the sex-specific mean value there was a slight increased risk of colorectal cancer associated with a 5 cm increase in waist circumference at wave 2 (HR = 1.08; 0.97, 1.21).
  
  
  CONCLUSIONS
  Increases in waist circumference and weight during midlife do not appear to be associated with the risk of colorectal cancer.
authors.affiliation: Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Bouverie Street, Melbourne, 3010, Australia. emily.karahalios@unimelb.edu.au.
authors.forename: Amalia
authors.initials: A
authors.lastname: Karahalios
authors.affiliation: Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Bouverie Street, Melbourne, 3010, Australia. julieas@unimelb.edu.au.|Cancer Epidemiology Centre, Cancer Council Victoria, 615 St Kilda Road, Melbourne, 3004, Australia. julieas@unimelb.edu.au.
authors.forename: Julie A
authors.initials: JA
authors.lastname: Simpson
authors.affiliation: Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Bouverie Street, Melbourne, 3010, Australia. severi.baglietto@gmail.com.|Cancer Epidemiology Centre, Cancer Council Victoria, 615 St Kilda Road, Melbourne, 3004, Australia. severi.baglietto@gmail.com.|Team 9, Lifestyle, Genes and health: integrative trans-generational epidemiology, Inserm U1018, Centre for Research in Epidemiology and Population Health, Gustave Roussy Institute, 114 rue Edouard Vaillant, Villejuif Cedex, 94805, France. severi.baglietto@gmail.com.|Paris-South University, Villejuif, France. severi.baglietto@gmail.com.
authors.forename: Laura
authors.initials: L
authors.lastname: Baglietto
authors.affiliation: Cancer Epidemiology Centre, Cancer Council Victoria, 615 St Kilda Road, Melbourne, 3004, Australia. Robert.MacInnis@cancervic.org.au.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: MacInnis
authors.affiliation: Cancer Epidemiology Centre, Cancer Council Victoria, 615 St Kilda Road, Melbourne, 3004, Australia. Allison.Hodge@cancervic.org.au.
authors.forename: Allison M
authors.initials: AM
authors.lastname: Hodge
authors.affiliation: Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Bouverie Street, Melbourne, 3010, Australia. Graham.Giles@cancervic.org.au.|Cancer Epidemiology Centre, Cancer Council Victoria, 615 St Kilda Road, Melbourne, 3004, Australia. Graham.Giles@cancervic.org.au.
authors.forename: Graham G
authors.initials: GG
authors.lastname: Giles
authors.affiliation: Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Bouverie Street, Melbourne, 3010, Australia. d.english@unimelb.edu.au.|Cancer Epidemiology Centre, Cancer Council Victoria, 615 St Kilda Road, Melbourne, 3004, Australia. d.english@unimelb.edu.au.
authors.forename: Dallas R
authors.initials: DR
authors.lastname: English
mesh_terms: D000328:Adult; D000368:Aged; D001315:Australia; D001835:Body Weight; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000209:etiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications; D011159:Population Surveillance; D016016:Proportional Hazards Models; D012306:Risk; D055105:Waist Circumference