title: Association of skirt size and postmenopausal breast cancer risk in older women: a cohort study within the UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS).
abstract: OBJECTIVE
  Several studies suggest that overall and central-obesity are associated with increased breast cancer (BC) risk in postmenopausal-women. However, there are no studies investigating changes of central obesity and BC. We report on the association of BC risk with self-reported skirt size (SS; waist-circumference proxy) changes between 20s and postmenopausal-age.
  
  
  METHODS
  Prospective cohort-study.
  
  
  METHODS
  UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) involving the nine trial centres in England.
  
  
  METHODS
  Postmenopausal-women aged >50 with no known history of BC prior to or on the day of completion of the study-entry questionnaire.
  
  
  METHODS
  At recruitment and at study entry, women were asked to complete a questionnaire. Women were followed-up via 'flagging' at the NHS Information Centre in England and the Hospital Episode Statistics.
  Time to initial BC diagnosis.
  
  
  RESULTS
  Between 2 January 2005 and 1 July 2010, 92,834 UKCTOCS participants (median age 64.0) completed the study-entry questionnaire. During median follow-up of 3.19 years (25th-75th centile: 2.46-3.78), 1090 women developed BC. Model adjusted analysis for potential confounders showed body mass index (BMI) at recruitment to UKCTOCS (HR for a 5 unit change=1.076, 95% CI 1.012 to 1.136), current SS at study entry (HR=1.051; 95% CI 1.014 to 1.089) and change in SS per 10 years (CSS) (HR=1.330; 95% CI 1.121 to 1.579) were associated with increased BC risk but not SS at 25 (HR=1.006; 95% CI 0.958 to 1.056). CSS was the most predictive singe adiposity measure and further analysis including both CSS and BMI in the model revealed CSS remained significant (HR=1.266; 95% CI 1.041 to 1.538) but not BMI (HR=1.037; 95% CI 0.970 to 1.109).
  
  
  CONCLUSIONS
  CSS is associated with BC risk independent of BMI. A unit increase in UK SS (eg, 12-14) every 10-years between 25 and postmenopausal-age is associated with postmenopausal BC risk by 33%. Validation of these results could provide women with a simple and easy to understand message.
  
  
  BACKGROUND
  ISRCTN22488978.
authors.affiliation: Department of Women's Cancer, Institute for Women's Health, University College London, London, UK.
authors.forename: Evangelia-Ourania
authors.initials: EO
authors.lastname: Fourkala
authors.affiliation: Department of Women's Cancer, Institute for Women's Health, University College London, London, UK.
authors.forename: Matthew
authors.initials: M
authors.lastname: Burnell
authors.affiliation: Department of Women's Cancer, Institute for Women's Health, University College London, London, UK.
authors.forename: Catherine
authors.initials: C
authors.lastname: Cox
authors.affiliation: Department of Women's Cancer, Institute for Women's Health, University College London, London, UK.
authors.forename: Andy
authors.initials: A
authors.lastname: Ryan
authors.affiliation: University College London Hospitals NHS Foundation Trust, London, UK.
authors.forename: Laura Currin
authors.initials: LC
authors.lastname: Salter
authors.affiliation: Department of Women's Cancer, Institute for Women's Health, University College London, London, UK.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Gentry-Maharaj
authors.affiliation: MRC Clinical Trials Unit, London, UK.
authors.forename: Mahesh
authors.initials: M
authors.lastname: Parmar
authors.affiliation: Department of Women's Cancer, Institute for Women's Health, University College London, London, UK Academic Health Science Centre, University of Manchester, Manchester, UK.
authors.forename: Ian
authors.initials: I
authors.lastname: Jacobs
authors.affiliation: Department of Women's Cancer, Institute for Women's Health, University College London, London, UK.
authors.forename: Usha
authors.initials: U
authors.lastname: Menon
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology*; D003020:Clothing; D015331:Cohort Studies; D055088:Early Detection of Cancer; D005260:Female; D006801:Humans; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000453:epidemiology; D017698:Postmenopause; D018570:Risk Assessment; D011795:Surveys and Questionnaires; D006113:United Kingdom; D055105:Waist Circumference
keywords: ONCOLOGY