title: Assessing within-woman changes in mammographic density: a comparison of fully versus semi-automated area-based approaches.
abstract: BACKGROUND
  Mammographic density (MD) varies throughout a woman's life. We compared the performance of a fully automated (ImageJ-based) method to the observer-dependent Cumulus approach in the assessment of within-woman changes in MD over time.
  
  
  METHODS
  MD was assessed in annual pre-diagnostic films (from age 40 to early 50s) from 313 breast cancer cases and 452 matched controls using Cumulus (left medio-lateral oblique (MLO) readings) and the ImageJ-based method (mean left-right MLO readings). Linear mixed models were used to compare within-woman changes in MD among controls. Associations between individual-specific MD trajectories and breast cancer were examined using conditional logistic regression.
  
  
  RESULTS
  The age-related trajectories predicted by Cumulus and the ImageJ-based method were similar for all MD measures, except that the ImageJ-based method yielded slightly higher (by 2.54%, 95% CI 2.07%, 3.00%) estimates for percent MD. For both methods, the yearly rate of change in percent MD was twice faster after menopause than before, and higher BMI was associated with lower mean percent MD, but not associated with rate of change. Both methods yielded similar associations of individual-specific MD trajectories with breast cancer risk.
  
  
  CONCLUSIONS
  The ImageJ-based method is a valid fully automated alternative to Cumulus for measuring within-woman changes in MD in digitized films. The Age Trial is registered as an International Standard Randomized Controlled Trial, number ISRCTN24647151.
authors: Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
authors: Marta Cecilia
authors: MC
authors: Busana
authors: Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
authors: Bianca L
authors: BL
authors: De Stavola
authors: Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.|Department of Obstetrics and Gynaecology, University of Cambridge, Box 223, Level 2, The Rosie Hospital, Robinson Way, Cambridge, CB2 0SW, UK.
authors: Ulla
authors: U
authors: Sovio
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Box 281, 171 77, Stockholm, Sweden.
authors: Jingmei
authors: J
authors: Li
authors: Centre for Cancer Prevention, Wolfson Institute of Preventive Medicine, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK.
authors: Sue
authors: S
authors: Moss
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Box 281, 171 77, Stockholm, Sweden.
authors: Keith
authors: K
authors: Humphreys
authors: Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. isabel.silva@lshtm.ac.uk.
authors: Isabel
authors: I
authors: dos-Santos-Silva
mesh_terms: D000328:Adult; D001940:Breast / Q000378:metabolism* / Q000473:pathology; D000071060:Breast Density; D001943:Breast Neoplasms; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D042361:Mammary Glands, Human / Q000002:abnormalities*; D008327:Mammography / Q000379:methods*; D008875:Middle Aged; D012307:Risk Factors
keywords: Breast cancer; Breast density; Mammographic density; Pre-menopausal