title: A retrospective observational study examining the characteristics and outcomes of tumours diagnosed within and without of the English NHS Bowel Cancer Screening Programme.
abstract: BACKGROUND
  Colorectal cancer is common in England and, with long-term survival relatively poor, improving outcomes is a priority. A major initiative to reduce mortality from the disease has been the introduction of the National Health Service (NHS) Bowel Cancer Screening Programme (BCSP). Combining data from the BCSP with that in the National Cancer Data Repository (NCDR) allows all tumours diagnosed in England to be categorised according to their involvement with the BCSP. This study sought to quantify the characteristics of the tumours diagnosed within and outside the BCSP and investigate its impact on outcomes.
  
  
  METHODS
  Linkage of the NCDR and BCSP data allowed all tumours diagnosed between July 2006 and December 2008 to be categorised into four groups; screen-detected tumours, screening-interval tumours, tumours diagnosed in non-participating invitees and tumours diagnosed in those never invited to participate. The characteristics, management and outcome of tumours in each category were compared.
  
  
  RESULTS
  In all, 76 943 individuals were diagnosed with their first primary colorectal cancer during the study period. Of these 2213 (2.9%) were screen-detected, 623 (0.8%) were screening-interval cancers, 1760 (2.3%) were diagnosed in individuals in non-participating invitees and 72 437 (94.1%) were diagnosed in individuals not invited to participate in the programme due to its ongoing roll-out over the time period studied. Screen-detected tumours were identified at earlier Dukes' stages, were more likely to be managed with curative intent and had significantly better outcomes than tumours in other categories.
  
  
  CONCLUSIONS
  Screen-detected cancers had a significantly better prognosis than other tumours and this would suggest that the BCSP should reduce mortality from colorectal cancer in England.
authors: Colorectal Cancer Epidemiology Group, Leeds Institute of Molecular Medicine, University of Leeds, Level 6, Bexley Wing, St James's Institute of Oncology, St James's Hospital, Leeds LS9 7TF, UK. eva.morris@nycris.leedsth.nhs.uk
authors: E J A
authors: EJ
authors: Morris
authors: L E
authors: LE
authors: Whitehouse
authors: T
authors: T
authors: Farrell
authors: C
authors: C
authors: Nickerson
authors: J D
authors: JD
authors: Thomas
authors: P
authors: P
authors: Quirke
authors: M D
authors: MD
authors: Rutter
authors: C
authors: C
authors: Rees
authors: P J
authors: PJ
authors: Finan
authors: J R
authors: JR
authors: Wilkinson
authors: J
authors: J
authors: Patnick
mesh_terms: D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000453:epidemiology / Q000473:pathology; D055088:Early Detection of Cancer / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D011379:Prognosis; D012042:Registries; D012189:Retrospective Studies; D013222:State Medicine; D015996:Survival Rate; D006113:United Kingdom / Q000453:epidemiology