title: Meta-analysis shows that detection of circulating tumor cells indicates poor prognosis in patients with colorectal cancer.
abstract: OBJECTIVE
  The prognostic significance of circulating (CTCs) and disseminated tumor cells in patients with colorectal cancer (CRC) is controversial. We performed a meta-analysis of available studies to assess whether the detection of tumor cells in the blood and bone marrow (BM) of patients diagnosed with primary CRC can be used as a prognostic factor.
  
  
  METHODS
  We searched the Medline, Biosis, Science Citation Index, and Embase databases and reference lists of relevant articles (including review articles) for studies that assessed the prognostic relevance of tumor cell detection in the peripheral blood (PB), mesenteric/portal blood (MPB), or BM of patients with CRC. Meta-analyses were performed using a random effects model, with hazard ratio (HR) and 95% confidence intervals (95% CIs) as effect measures.
  
  
  RESULTS
  A total of 36 studies, including 3094 patients, were eligible for final analyses. Pooled analyses that combined all sampling sites (PB, MPB, and BM) associated the detection of tumor cells with poor recurrence-free survival (RFS) (HR = 3.24 [95% CI: 2.06-5.10], n = 26, I(2) = 77%) and overall survival (OS) (2.28 [1.55-3.38], n = 21, I(2) = 66%). Stratification by sampling site showed that detection of tumor cells in the PB compartment was a statistically significant prognostic factor (RFS: 3.06 [1.74-5.38], n = 19, I(2) = 78%; OS: 2.70 [1.74-4.20], n = 16, I(2) = 59%) but not in the MPB (RFS: 4.12 [1.01-16.83], n = 8, I(2) = 75%; OS: 4.80 [0.81-28.32], n = 5, I(2) = 82%) or in the BM (RFS: 2.17 [0.94-5.03], n = 4, I(2) = 78%; OS: 1.50 [0.52-4.32], n = 3, I(2) = 84%).
  
  
  CONCLUSIONS
  Detection of CTCs in the PB indicates poor prognosis in patients with primary CRC.
authors.affiliation: Department of General, Visceral, and Transplantation Surgery, University of Heidelberg, Germany.
authors.forename: Nuh N
authors.initials: NN
authors.lastname: Rahbari
authors.forename: Maximilian
authors.initials: M
authors.lastname: Aigner
authors.forename: Kristian
authors.initials: K
authors.lastname: Thorlund
authors.forename: Nathan
authors.initials: N
authors.lastname: Mollberg
authors.forename: Edith
authors.initials: E
authors.lastname: Motschall
authors.forename: Katrin
authors.initials: K
authors.lastname: Jensen
authors.forename: Markus K
authors.initials: MK
authors.lastname: Diener
authors.forename: Markus W
authors.initials: MW
authors.lastname: Büchler
authors.forename: Moritz
authors.initials: M
authors.lastname: Koch
authors.forename: Jürgen
authors.initials: J
authors.lastname: Weitz
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D019317:Evidence-Based Medicine; D006801:Humans; D008875:Middle Aged; D009367:Neoplasm Staging; D009360:Neoplastic Cells, Circulating / Q000473:pathology*; D018570:Risk Assessment; D012307:Risk Factors; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult