title: The TOMMY trial: a comparison of TOMosynthesis with digital MammographY in the UK NHS Breast Screening Programme--a multicentre retrospective reading study comparing the diagnostic performance of digital breast tomosynthesis and digital mammography with digital mammography alone.
abstract: BACKGROUND
  Digital breast tomosynthesis (DBT) is a three-dimensional mammography technique with the potential to improve accuracy by improving differentiation between malignant and non-malignant lesions.
  
  
  OBJECTIVE
  The objectives of the study were to compare the diagnostic accuracy of DBT in conjunction with two-dimensional (2D) mammography or synthetic 2D mammography, against standard 2D mammography and to determine if DBT improves the accuracy of detection of different types of lesions.
  
  
  METHODS
  Women (aged 47-73 years) recalled for further assessment after routine breast screening and women (aged 40-49 years) with moderate/high of risk of developing breast cancer attending annual mammography screening were recruited after giving written informed consent.
  
  
  METHODS
  All participants underwent a two-view 2D mammography of both breasts and two-view DBT imaging. Image-processing software generated a synthetic 2D mammogram from the DBT data sets.
  In an independent blinded retrospective study, readers reviewed (1) 2D or (2) 2D + DBT or (3) synthetic 2D + DBT images for each case without access to original screening mammograms or prior examinations. Sensitivities and specificities were calculated for each reading arm and by subgroup analyses.
  
  
  RESULTS
  Data were available for 7060 subjects comprising 6020 (1158 cancers) assessment cases and 1040 (two cancers) family history screening cases. Overall sensitivity was 87% [95% confidence interval (CI) 85% to 89%] for 2D only, 89% (95% CI 87% to 91%) for 2D + DBT and 88% (95% CI 86% to 90%) for synthetic 2D + DBT. The difference in sensitivity between 2D and 2D + DBT was of borderline significance (p = 0.07) and for synthetic 2D + DBT there was no significant difference (p = 0.6). Specificity was 58% (95% CI 56% to 60%) for 2D, 69% (95% CI 67% to 71%) for 2D + DBT and 71% (95% CI 69% to 73%) for synthetic 2D + DBT. Specificity was significantly higher in both DBT reading arms for all subgroups of age, density and dominant radiological feature (p < 0.001 all cases). In all reading arms, specificity tended to be lower for microcalcifications and higher for distortion/asymmetry. Comparing 2D + DBT to 2D alone, sensitivity was significantly higher: 93% versus 86% (p < 0.001) for invasive tumours of size 11-20 mm. Similarly, for breast density 50% or more, sensitivities were 93% versus 86% (p = 0.03); for grade 2 invasive tumours, sensitivities were 91% versus 87% (p = 0.01); where the dominant radiological feature was a mass, sensitivities were 92% and 89% (p = 0.04) For synthetic 2D + DBT, there was significantly (p = 0.006) higher sensitivity than 2D alone in invasive cancers of size 11-20 mm, with a sensitivity of 91%.
  
  
  CONCLUSIONS
  The specificity of DBT and 2D was better than 2D alone but there was only marginal improvement in sensitivity. The performance of synthetic 2D appeared to be comparable to standard 2D. If these results were observed with screening cases, DBT and 2D mammography could benefit to the screening programme by reducing the number of women recalled unnecessarily, especially if a synthetic 2D mammogram were used to minimise radiation exposure. Further research is required into the feasibility of implementing DBT in a screening setting, prognostic modelling on outcomes and mortality, and comparison of 2D and synthetic 2D for different lesion types.
  
  
  BACKGROUND
  Current Controlled Trials ISRCTN73467396.
  
  
  BACKGROUND
  This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 19, No. 4. See the HTA programme website for further project information.
authors.affiliation: Department of Radiology, University of Cambridge, Cambridge, UK.
authors.forename: Fiona J
authors.initials: FJ
authors.lastname: Gilbert
authors.affiliation: Department of Radiology, University of Cambridge, Cambridge, UK.
authors.forename: Lorraine
authors.initials: L
authors.lastname: Tucker
authors.affiliation: Aberdeen Biomedical Imaging Centre, University of Aberdeen, Aberdeen, UK.
authors.forename: Maureen Gc
authors.initials: MG
authors.lastname: Gillan
authors.affiliation: Department of Radiology, University of Cambridge, Cambridge, UK.
authors.forename: Paula
authors.initials: P
authors.lastname: Willsher
authors.affiliation: Jarvis Breast Centre, Guildford, UK.
authors.forename: Julie
authors.initials: J
authors.lastname: Cooke
authors.affiliation: North East Scotland Breast Screening Centre, Aberdeen, UK.
authors.forename: Karen A
authors.initials: KA
authors.lastname: Duncan
authors.affiliation: Breast Radiology, King's College Hospital, London, UK.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Michell
authors.affiliation: West of Scotland Breast Screening Service, Glasgow, UK.
authors.forename: Hilary M
authors.initials: HM
authors.lastname: Dobson
authors.affiliation: The Nightingale Centre, University Hospital South Manchester, Manchester, UK.
authors.forename: Yit Yoong
authors.initials: YY
authors.lastname: Lim
authors.affiliation: Department of Radiology, St Bartholomew's Hospital, London, UK.
authors.forename: Hema
authors.initials: H
authors.lastname: Purushothaman
authors.affiliation: National Co-ordinating Centre for Physics of Mammography, Royal Surrey County Hospital, Guildford, UK.
authors.forename: Celia
authors.initials: C
authors.lastname: Strudley
authors.affiliation: Department of Imaging Science and Biomedical Engineering, University of Manchester, Manchester, UK.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Astley
authors.affiliation: East Anglian Regional Radiation Protection Service, Cambridge University Hospitals, Cambridge, UK.
authors.forename: Oliver
authors.initials: O
authors.lastname: Morrish
authors.affiliation: National Co-ordinating Centre for Physics of Mammography, Royal Surrey County Hospital, Guildford, UK.
authors.forename: Kenneth C
authors.initials: KC
authors.lastname: Young
authors.affiliation: Wolfson Institute of Preventive Medicine, Queen Mary University of London, London, UK.
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Duffy
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000473:pathology; D055088:Early Detection of Cancer / Q000379:methods*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation*; D008327:Mammography / Q000379:methods*; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity