title: A comparison of tumour and host prognostic factors in screen-detected vs nonscreen-detected colorectal cancer: a contemporaneous study.
abstract: OBJECTIVE
  In addition to TNM stage there are adverse tumour and host factors, such as venous invasion and the presence of an elevated systemic inflammatory response (SIR), that influence the outcome in colorectal cancer. The present study aimed to examine how these factors varied in screen-detected (SD) and nonscreen-detected (NSD) tumours.
  
  
  METHODS
  Prospectively maintained databases of the prevalence round of a biennial population faecal occult blood test screening programme and a regional cancer audit database were analysed. Interval cancers (INT) were defined as cancers identified within 2 years of a negative screening test.
  
  
  RESULTS
  Of the 395 097 people invited, 204 535 (52%) responded, 6159 (3%) tested positive and 421 (9%) had cancer detected. A further 708 NSD patients were identified [468 (65%) nonresponders, 182 (25%) INT cancers and 58 (10%) who did not attend or did not have cancer diagnosed at colonoscopy]. Comparing SD and NSD patients, SD patients were more likely to be male, and have a tumour with a lower TNM stage (both P < 0.05). On stage-by-stage analysis, SD patients had less evidence of an elevated SIR (P < 0.05). Both the presence of venous invasion (P = 0.761) and an elevated SIR (P = 0.059) were similar in those with INT cancers and in those that arose in nonresponders.
  
  
  CONCLUSIONS
  Independent of TNM stage, SD tumours have more favourable host prognostic factors than NSD tumours. There is no evidence that INT cancers are biologically more aggressive than those that develop in the rest of the population and are hence likely to be due to limitations of screening in its current format.
authors: Academic Unit of Colorectal Surgery, Glasgow Royal Infirmary, University of Glasgow, Glasgow, UK. david.mansouri@glasgow.ac.uk.
authors: D
authors: D
authors: Mansouri
authors: Academic Unit of Colorectal Surgery, Glasgow Royal Infirmary, University of Glasgow, Glasgow, UK.
authors: D C
authors: DC
authors: McMillan
authors: Academic Unit of Colorectal Surgery, Glasgow Royal Infirmary, University of Glasgow, Glasgow, UK.
authors: E
authors: E
authors: McIlveen
authors: Department of Public Health Screening Unit, NHS Greater Glasgow and Clyde, Glasgow, UK.
authors: E M
authors: EM
authors: Crighton
authors: West of Scotland Cancer Surveillance Unit, University of Glasgow, Glasgow, UK.
authors: D S
authors: DS
authors: Morrison
authors: Academic Unit of Colorectal Surgery, Glasgow Royal Infirmary, University of Glasgow, Glasgow, UK.
authors: P G
authors: PG
authors: Horgan
mesh_terms: D000368:Aged; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000473:pathology; D016208:Databases, Factual; D055088:Early Detection of Cancer / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D009367:Neoplasm Staging; D009780:Occult Blood; D011379:Prognosis; D011446:Prospective Studies; D012737:Sex Factors; D013997:Time Factors
keywords: Colorectal cancer screening; faecal immunochemical test; gFOBt; host systemic inflammation; tumour factors