title: Systematic review of risk factors for metastasis to para-aortic lymph nodes in gastric cancer.
abstract: OBJECTIVE
  A meta-analysis was performed to evaluate the possible predictors of the positive PALN(para-aortic lymph nodes) for identifing specific patients who are at high risk of PALN metastases and for whom super-extended lymphadenectomy or pre-operative DCS therapy could be recommended.
  
  
  METHODS
  Five databases (PUBMED, EMBASE, the Cochrane Library and the China Biological Medicine Database, CNKI) were searched that finally identified 11 candidate studies. Original data were abstracted from each study and used to calculate odds ratios. The random effects or fixed-effect model was used to combine odds ratios to determine the strength of the associations.
  
  
  RESULTS
  In this study, we eventually found 6 risk factors in the clinicopathologic characteristics including tumour located in the upper third(P < 0.01, OR = 2.19), tumour size exceeding 5 cm(P < 0.01, OR = 3.42), tumour infiltrating deeper than T2 (P < 0.01, OR = 2.07), tumour in the stage N2 and N3(P < 0.01, OR = 12.03), and tumour regarded as the poorly differentiated type by the histologic classification (P < 0.01, OR = 2.49)and the Borrman 3,4 type by the macroscopic classification(P < 0.01, OR = 2.58). Moreover, the metastasis of lower lymph nodal stations may be the predictors of the positive PALN especially NO.1, NO.3, NO.7 and NO.9 stations which had evidently higher odd ratios (OR>7) over others.
  
  
  CONCLUSIONS
  Although we cannot conduct a multivariate logistic regression to assess all risk factors together because of the limited information extracted from the studies, the risk factors above-mentioned may also have some indications especially when they have strong relationships with the positive PALN(OR>3). D2 Plus Para-Aortic Lymphadenectomy or pre-operative chemotherapy may be required for those patients who have a high risk for metastasis to PALN so that they may get better prognosis.
authors.affiliation: Department of General Surgery and Center of Minimal Invasive Gastrointestinal Surgery, Southwest Hospital, Third Military Medical University, Gaotanyan 30, Shapingba, Chongqing, China.
authors.forename: Zhou
authors.initials: Z
authors.lastname: Junfeng
authors.forename: Hao
authors.initials: H
authors.lastname: Yingxue
authors.forename: Yu
authors.initials: Y
authors.lastname: Peiwu
mesh_terms: D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D012307:Risk Factors; D013274:Stomach Neoplasms / Q000556:secondary*
keywords: D2 plus; Gastric cancer; Metastasis; Para-aortic lymph nodes; Para-aortic lymphadenectomy; Risk factors