title: Systematic review of prognostic importance of extramural venous invasion in rectal cancer.
abstract: OBJECTIVE
  To systematically review the survival outcomes relating to extramural venous invasion in rectal cancer.
  
  
  METHODS
  A systematic review was conducted using PRISMA guidelines. An electronic search was carried out using MEDLINE, EMBASE, CINAHL, Cochrane library databases, Google scholar and PubMed until October 2014. Search terms were used in combination to yield articles on extramural venous invasion in rectal cancer. Outcome measures included prevalence and 5-year survival rates. These were graphically displayed using Forest plots. Statistical analysis of the data was carried out.
  
  
  RESULTS
  Fourteen studies reported the prevalence of extramural venous invasion (EMVI) positive patients. Prevalence ranged from 9%-61%. The pooled prevalence of EMVI positivity was 26% [Random effects: Event rate 0.26 (0.18, 0.36)]. Most studies showed that EMVI related to worse oncological outcomes. The pooled overall survival was 39.5% [Random effects: Event rate 0.395 (0.29, 0.51)].
  
  
  CONCLUSIONS
  Historically, there has been huge variation in the prevalence of EMVI through inconsistent reporting. However the presence of EMVI clearly leads to worse survival outcomes. As detection rates become more consistent, EMVI may be considered as part of risk-stratification in rectal cancer. Standardised histopathological definitions and the use of magnetic resonance imaging to identify EMVI will improve detection rates in the future.
authors.affiliation: Manish Chand, Muhammed RS Siddiqui, Gina Brown, Royal Marsden Hospital, London SM2 5PT, United Kingdom.
authors.forename: Manish
authors.initials: M
authors.lastname: Chand
authors.affiliation: Manish Chand, Muhammed RS Siddiqui, Gina Brown, Royal Marsden Hospital, London SM2 5PT, United Kingdom.
authors.forename: Muhammed R S
authors.initials: MR
authors.lastname: Siddiqui
authors.affiliation: Manish Chand, Muhammed RS Siddiqui, Gina Brown, Royal Marsden Hospital, London SM2 5PT, United Kingdom.
authors.forename: Ian
authors.initials: I
authors.lastname: Swift
authors.affiliation: Manish Chand, Muhammed RS Siddiqui, Gina Brown, Royal Marsden Hospital, London SM2 5PT, United Kingdom.
authors.forename: Gina
authors.initials: G
authors.lastname: Brown
mesh_terms: D006801:Humans; D009361:Neoplasm Invasiveness; D011237:Predictive Value of Tests; D011379:Prognosis; D012004:Rectal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D012307:Risk Factors; D016019:Survival Analysis; D014680:Veins / Q000473:pathology*
keywords: Extramural venous invasion; Magnetic resonance imaging; Overall survival; Pathology; Rectal cancer; Vascular invasion
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