title: Screen-detected colorectal cancers are associated with an improved outcome compared with stage-matched interval cancers.
abstract: BACKGROUND
  Colorectal cancers (CRCs) detected through the NHS Bowel Cancer Screening Programme (BCSP) have been shown to have a more favourable outcome compared to non-screen-detected cancers. The aim was to identify whether this was solely due to the earlier stage shift of these cancers, or whether other factors were involved.
  
  
  METHODS
  A combination of a regional CRC registry (Northern Colorectal Cancer Audit Group) and the BCSP database were used to identify screen-detected and interval cancers (diagnosed after a negative faecal occult blood test, before the next screening round), diagnosed between April 2007 and March 2010, within the North East of England. For each Dukes' stage, patient demographics, tumour characteristics, and survival rates were compared between these two groups.
  
  
  RESULTS
  Overall, 322 screen-detected cancers were compared against 192 interval cancers. Screen-detected Dukes' C and D CRCs had a superior survival rate compared with interval cancers (P=0.014 and P=0.04, respectively). Cox proportional hazards regression showed that Dukes' stage, tumour location, and diagnostic group (HR 0.45, 95% CI 0.29-0.69, P<0.001 for screen-detected CRCs) were all found to have a significant impact on the survival of patients.
  
  
  CONCLUSIONS
  The improved survival of screen-detected over interval cancers for stages C and D suggest that there may be a biological difference in the cancers in each group. Although lead-time bias may have a role, this may be related to a tumour's propensity to bleed and therefore may reflect detection through current screening tests.
authors.affiliation: 1] Northern Colorectal Cancer Audit Group, North East England, UK [2] School of Medicine, Pharmacy and Health, University of Durham, Durham, UK [3] Northern Region Endoscopy Group, North East England, UK.
authors.forename: M D
authors.initials: MD
authors.lastname: Gill
authors.affiliation: 1] School of Medicine, Pharmacy and Health, University of Durham, Durham, UK [2] Northern Region Endoscopy Group, North East England, UK.
authors.forename: M G
authors.initials: MG
authors.lastname: Bramble
authors.affiliation: Leeds Institute of Cancer and Pathology, University of Leeds, Leeds, UK.
authors.forename: M A
authors.initials: MA
authors.lastname: Hull
authors.affiliation: 1] Northern Colorectal Cancer Audit Group, North East England, UK [2] Northern Region Endoscopy Group, North East England, UK.
authors.forename: S J
authors.initials: SJ
authors.lastname: Mills
authors.affiliation: Leeds Institute of Cancer and Pathology, University of Leeds, Leeds, UK.
authors.forename: E
authors.initials: E
authors.lastname: Morris
authors.affiliation: 1] Northern Colorectal Cancer Audit Group, North East England, UK [2] Northern Region Endoscopy Group, North East England, UK.
authors.forename: D M
authors.initials: DM
authors.lastname: Bradburn
authors.affiliation: Royal Victoria Infirmary, Newcastle, UK.
authors.forename: Y
authors.initials: Y
authors.lastname: Bury
authors.affiliation: 1] Northern Region Endoscopy Group, North East England, UK [2] South Tyneside Foundation Trust, South Tyneside, UK.
authors.forename: C E
authors.initials: CE
authors.lastname: Parker
authors.affiliation: 1] Northern Region Endoscopy Group, North East England, UK [2] North Tyneside General Hospital, Northumbria Healthcare NHS Foundation Trust, Northumberland, UK.
authors.forename: T J W
authors.initials: TJ
authors.lastname: Lee
authors.affiliation: 1] School of Medicine, Pharmacy and Health, University of Durham, Durham, UK [2] Northern Region Endoscopy Group, North East England, UK [3] South Tyneside Foundation Trust, South Tyneside, UK.
authors.forename: C J
authors.initials: CJ
authors.lastname: Rees
mesh_terms: D000368:Aged; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000401:mortality / Q000473:pathology; D055088:Early Detection of Cancer; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D016016:Proportional Hazards Models