title: Body mass index and participation in organized mammographic screening: a prospective cohort study.
abstract: BACKGROUND
  Breast cancer is the leading cancer among women, and early diagnosis is essential for future prognosis. Evidence from mainly cross-sectional US studies with self-reported exposure and outcome found positive association of body mass index (BMI) with non-participation in mammographic screening, but hardly addressed the influence of potential effect-modifiers. We studied the association between objective measures of BMI and participation in mammographic screening in a Danish prospective cohort, and explored the influence of menopausal status, hormone therapy (HT), previous screening participation, and morbidities on this relationship.
  
  
  METHODS
  A total of 5,134 women from the Diet, Cancer, and Health cohort who were invited to population based mammographic screening in Copenhagen were included in analysis. Women were 50-64 years old at inclusion (1993-97) when their height and weight were measured and covariates collected via questionnaire. Odds ratios (OR) and 95% confidence intervals (CI) for the association between BMI and mammographic screening participation were estimated by logistic regression, adjusted for other breast cancer risk factors and morbidities. Effect modification was evaluated by an interaction term and tested by Wald test.
  
  
  RESULTS
  Underweight (BMI < 18.5 kg/m(2), OR: 95% CI; 2.24: 1.27-3.96) and obese women of class II (BMI 35-40 kg/m(2), 1.54: 0.99-2.39) and III (BMI ≥ 40 kg/m(2), 1.81: 0.95-3.44) had significantly higher odds of non-participation than women with normal weight. This association was limited to postmenopausal women (Wald test p = 0.08), with enhanced non-participation in underweight (2.83: 1.52-5.27) and obese women of class II and III (1.84: 1.15-2.95; 2.47: 1.20-5.06) as compared to normal weight postmenopausal women. There was no effect modification by HT, previous screening participation, or morbidities, besides suggestive evidence of enhanced non-participation in diabetic overweight and obese women.
  
  
  CONCLUSIONS
  Underweight and very obese postmenopausal women were significantly less likely to participate in mammographic screening than women with normal weight, while BMI was not related to screening in premenopausal women. Effect of BMI on mammographic screening participation was not significantly modified by HT, previous screening participation, or morbidities.
authors.affiliation: Department of Public Health, University of Copenhagen, Øster Farimagsgade 5, 1014, Copenhagen, Denmark. sohe@sund.ku.dk.
authors.forename: Sophie Sell
authors.initials: SS
authors.lastname: Hellmann
authors.affiliation: Department of Public Health, University of Copenhagen, Øster Farimagsgade 5, 1014, Copenhagen, Denmark. sissenj@sund.ku.dk.
authors.forename: Sisse Helle
authors.initials: SH
authors.lastname: Njor
authors.affiliation: Department of Public Health, University of Copenhagen, Øster Farimagsgade 5, 1014, Copenhagen, Denmark. elsebeth@sund.ku.dk.
authors.forename: Elsebeth
authors.initials: E
authors.lastname: Lynge
authors.affiliation: Department of Public Health, University of Copenhagen, Øster Farimagsgade 5, 1014, Copenhagen, Denmark. myeu@sund.ku.dk.
authors.forename: My
authors.initials: M
authors.lastname: von Euler-Chelpin
authors.affiliation: Danish Cancer Society, Institute of Cancer Epidemiology, Strandboulevarden 49, 2100, Copenhagen, Denmark. anja@cancer.dk.
authors.forename: Anja
authors.initials: A
authors.lastname: Olsen
authors.affiliation: Danish Cancer Society, Institute of Cancer Epidemiology, Strandboulevarden 49, 2100, Copenhagen, Denmark. annet@cancer.dk.
authors.forename: Anne
authors.initials: A
authors.lastname: Tjønneland
authors.affiliation: Diagnostic Imaging Centre, Copenhagen University Hospital Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark. ilse.vejborg@rh.regionh.dk.
authors.forename: Ilse
authors.initials: I
authors.lastname: Vejborg
authors.affiliation: Department of Public Health, University of Copenhagen, Øster Farimagsgade 5, 1014, Copenhagen, Denmark. Zorana.Andersen@sund.ku.dk.
authors.forename: Zorana Jovanovic
authors.initials: ZJ
authors.lastname: Andersen
mesh_terms: D015992:Body Mass Index; D001943:Breast Neoplasms / Q000175:diagnosis; D015331:Cohort Studies; D055088:Early Detection of Cancer / Q000379:methods*; D005260:Female; D006801:Humans; D008327:Mammography / Q000379:methods*; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology*; D010358:Patient Participation; D017698:Postmenopause; D017697:Premenopause; D011446:Prospective Studies; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology; D013851:Thinness / Q000453:epidemiology*