title: Adverse surgical outcomes in screen-detected ductal carcinoma in situ of the breast.
abstract: BACKGROUND
  The Sloane Project is the largest prospective audit of ductal carcinoma in situ (DCIS) worldwide, with over 12,000 patients registered between 2003 and 2012, accounting for 50% of screen-detected DCIS diagnosed in the United Kingdom (UK) over the period of accrual.
  
  
  METHODS
  Complete multidisciplinary data from 8313 patients with screen-detected DCIS were analysed for surgical outcome in relation to key radiological and pathological parameters for the cohort and also by hospital of treatment. Adverse surgical outcomes were defined as either failed breast conservation surgery (BCS) or mastectomy for small lesions (<20mm) (MFSL). Inter-hospital variation was analysed by grouping hospitals into high, medium and low frequency subgroups for these two adverse outcomes.
  
  
  RESULTS
  Patients with failed BCS or MFSL together accounted for 49% of all mastectomies. Of 6633 patients embarking on BCS, 799 (12.0%) required mastectomy. MFSL accounted for 510 (21%) of 2479 mastectomy patients. Failed BCS was associated with significant radiological under-estimation of disease extent and MFSL significant radiological over-estimation of disease extent. There was considerable and significant inter-hospital variation in failed BCS (range 3-32%) and MFSL (0-60%) of a hospital's BCS/mastectomy workload respectively. Conversely, there were no differences between the key radiological and pathological parameters in high, medium and low frequency adverse-outcome hospitals.
  
  
  CONCLUSIONS
  This evidence suggests significant practice variation, not patient factors, is responsible for these adverse surgical outcomes in screen-detected DCIS. The Sloane Project provides an evidence base for future practice benchmarking.
authors.affiliation: Department of Pathology, Western General Hospital, Edinburgh EH4 2XU, UK. Electronic address: jeremy.thomas@nhslothian.scot.nhs.uk.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Thomas
authors.affiliation: Department of Histopathology, Algenon-Firth Building, Leeds General Infirmary, Gt George Street, Leeds, UK. Electronic address: a.m.hanby@leeds.ac.uk.
authors.forename: Andrew
authors.initials: A
authors.lastname: Hanby
authors.affiliation: Research Oncology, Division of Cancer Studies, King's College London, 3rd Floor, Bermondsey Wing, Guy's Hospital, Great Maze Pond, London SE1 9RT, UK. Electronic address: sarah.pinder@kcl.ac.uk.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Pinder
authors.affiliation: Van Geest Cancer Centre, School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, UK. Electronic address: graham.balls@ntu.ac.uk.
authors.forename: Graham
authors.initials: G
authors.lastname: Ball
authors.affiliation: West Midlands Knowledge and Intelligence Team, Public Health England, 1st Floor, 5 St Philip's Place, Birmingham B3 2PW, UK. Electronic address: g.lawrence@nhs.net.
authors.forename: Gill
authors.initials: G
authors.lastname: Lawrence
authors.affiliation: Nightingale Centre and Genesis Prevention Centre, University Hospital of South Manchester, Southmoor Road, Manchester M23 9LT, UK. Electronic address: anthony.maxwell@manchester.ac.uk.
authors.forename: Anthony
authors.initials: A
authors.lastname: Maxwell
authors.affiliation: Cambridge Breast Unit and NIHR Cambridge Biomedical Research Centre, Cambridge University Hospitals NHS Foundation Trust, Box 97, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0QQ, UK. Electronic address: matthew.wallis@addenbrookes.nhs.uk.
authors.forename: Matthew
authors.initials: M
authors.lastname: Wallis
authors.affiliation: Department of Radiology, Ninewells Hospital and Medical School, Dundee DD1 9SY, UK. Electronic address: a.z.evans@dundee.ac.uk.
authors.forename: Andrew
authors.initials: A
authors.lastname: Evans
authors.affiliation: West of Scotland Breast Screening Service, Stock Exchange Court, 77 Nelson Mandela Place, Glasgow G2 1QT, UK. Electronic address: hilary.dobson@ggc.scot.nhs.uk.
authors.forename: Hilary
authors.initials: H
authors.lastname: Dobson
authors.affiliation: West Midlands Cancer Screening QA Reference Centre, Public Health England, 1st Floor, 5 St Philip's Place, Birmingham B3 2PW, UK. Electronic address: karen.clements@phe.gov.uk.
authors.forename: Karen
authors.initials: K
authors.lastname: Clements
authors.affiliation: Department of Surgical Oncology, MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA. Electronic address: a.m.thompson@dundee.ac.uk.
authors.forename: Alastair
authors.initials: A
authors.lastname: Thompson
mesh_terms: D000368:Aged; D002278:Carcinoma in Situ / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology / Q000601:surgery*; D018270:Carcinoma, Ductal, Breast / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology / Q000601:surgery*; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology / Q000601:surgery*; D055088:Early Detection of Cancer / Q000379:methods; D005260:Female; D006801:Humans; D008408:Mastectomy / Q000706:statistics & numerical data; D008485:Medical Audit; D008875:Middle Aged; D011446:Prospective Studies; D016896:Treatment Outcome; D006113:United Kingdom / Q000453:epidemiology
keywords: Breast screening; DCIS; Outcomes; Pathology; Practice variation; Radiology