title: Myeloid-derived suppressor cells in gastrointestinal cancers: A systematic review.
abstract: OBJECTIVE
  Gastrointestinal (GI) cancers are a heterogeneous group of cancers originating from the digestive system. Considering key roles of myeloid-derived suppressor cells (MDSCs) in the immunosuppression network, levels of MDSCs in patients with cancer are assumed to be of prognostic and predictive value. In this systematic review, we aimed to evaluate the clinical relevancy of MDSCs and their relationship with clinical features and prognosis of GI malignancies in patients with GI cancers.
  
  
  METHODS
  We searched Medline, Scopus, DART, OpenGrey, and ProQuest without applying any language filter up to 1 August 2015. Two of the authors independently reviewed search results for irrelevant and duplicate studies and extracted data from studies. We used tabulation to synthesize the findings of the studies and transformed data into a common rubric and calculated a weighted treatment effect across studies using Review Manager.
  
  
  RESULTS
  We found 1238 references in five databases, and after exclusion of irrelevant and duplicate studies, 17 studies with a total number of 1115 patients with GI cancers were included. A meta-analysis of three studies showed associations of high MDSC levels with higher mortality during follow-up periods (hazard ratio = 3.35; 95% confidence interval = 1.46-7.68, P = 0.0004). A meta-analysis of four studies showed that patients with higher levels of MDSC had higher odds of having an advanced cancer (odds ratio = 2.64; 95% confidence interval = 1.53-4.53; P = 0.0004). There were also significant associations between MDSC levels and relapse, tumor progression, lymph node involvement, and metastasis.
  
  
  CONCLUSIONS
  In conclusion, results of this systematic review based on the available literature suggest that MDSC levels are of clinical relevancy and prognostic and predictive value.
authors.affiliation: Research Center for Immunodeficiencies, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran.|Border of Immune Tolerance Education and Research Network (BITERN), Universal Scientific Education and Research Network (USERN), Tehran, Iran.
authors.forename: Armin
authors.initials: A
authors.lastname: Hirbod-Mobarakeh
authors.affiliation: Border of Immune Tolerance Education and Research Network (BITERN), Universal Scientific Education and Research Network (USERN), Tehran, Iran.|Students' Scientific Research Center, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Masoud
authors.initials: M
authors.lastname: Mirghorbani
authors.affiliation: Border of Immune Tolerance Education and Research Network (BITERN), Universal Scientific Education and Research Network (USERN), Tehran, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Hajiju
authors.affiliation: Border of Immune Tolerance Education and Research Network (BITERN), Universal Scientific Education and Research Network (USERN), Tehran, Iran.
authors.forename: Mahnaz
authors.initials: M
authors.lastname: Marvi
authors.affiliation: Border of Immune Tolerance Education and Research Network (BITERN), Universal Scientific Education and Research Network (USERN), Tehran, Iran.
authors.forename: Kiandokht
authors.initials: K
authors.lastname: Bashiri
authors.affiliation: Research Center for Immunodeficiencies, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran.|Border of Immune Tolerance Education and Research Network (BITERN), Universal Scientific Education and Research Network (USERN), Tehran, Iran.|Department of Infection and Immunity, School of Medicine and Biomedical Sciences, The University of Sheffield, Sheffield, UK.
authors.forename: Nima
authors.initials: N
authors.lastname: Rezaei
mesh_terms: D016206:Databases, Bibliographic; D018450:Disease Progression; D005770:Gastrointestinal Neoplasms / Q000276:immunology / Q000473:pathology; D006801:Humans; D007108:Immune Tolerance / Q000276:immunology*; D008207:Lymphatic Metastasis; D000072737:Myeloid-Derived Suppressor Cells / Q000276:immunology*; D009364:Neoplasm Recurrence, Local; D011237:Predictive Value of Tests; D011379:Prognosis
keywords: MDSC; gastrointestinal cancers; microenvironment; myeloid-derived suppressor cells; prognosis; survival; systematic review