title: A systematic review and meta-analysis on outcomes after Rx or R1 endoscopic resection of superficial gastric cancer.
abstract: OBJECTIVE
  Endoscopic resection is a standard treatment for gastric superficial lesions. A positive or a nonevaluable margin is considered a noncurative criterion. We aimed to systematically review recurrence, residual disease, lymph node metastasis (LNM) and cancer-related death following Rx/R1 resection of gastric lesions in the absence of other noncurative criteria.
  
  
  METHODS
  MEDLINE systematic review and meta-analysis by July 2014.
  
  
  RESULTS
  Data were extracted from 31 manuscripts. Definitions and results differed significantly. However, nonevaluable (HMx) and positive horizontal margins (HM1) were associated with 10% [95% confidence interval (CI) 5-15%] and 36% (95% CI 24-48%) rates of recurrence/residual disease, respectively, with an odds ratio of 2.85 (95% CI 1.6-5.8, P<0.01) for HM1 compared with HMx. Nonevaluable (VMx) or positive (VM1) vertical margin was associated with a 43% (95% CI 17-68%) rate of recurrence/residual. VMx/VM1 was associated with a higher risk of recurrence/residual compared with HMx/HM1 (odds ratio 3.76, 95% CI 1.71-6.82, P<0.01). The most common strategy after HMx/HM1 was endoscopic surveillance and retreatment, whereas surgery was recommended after VMx/VM1. No cases of LNM or cancer-related death were noticeable if neither submucosal invasion more than 500 µm nor lymphovascular infiltration was also reported.
  
  
  CONCLUSIONS
  Rx/R1 resection in the absence of other noncurative criteria does not appear to be a significant risk factor for LNM or cancer-related death. The risk of recurrence/residual disease is higher after HM1 than HMx and higher after VMx/VM1 than HMx/HM1. However, considerable heterogeneity was found in studies. Standard definitions should be created and applied in future studies.
authors.affiliation: aDepartment of Gastroenterology, Hospital Garcia de Orta, Almada bDepartment of Gastroenterology, Portuguese Oncology Institute cCINTESIS/Department of Biostatistics and Medical Informatics dDepartment of Physiology and Cardiothoracic Surgery, Cardiovascular Research & Development Unit, Porto Faculty of Medicine, Porto, Portugal.
authors.forename: Pedro C
authors.initials: PC
authors.lastname: Figueiredo
authors.forename: Pedro
authors.initials: P
authors.lastname: Pimentel-Nunes
authors.forename: Diogo
authors.initials: D
authors.lastname: Libânio
authors.forename: Mário
authors.initials: M
authors.lastname: Dinis-Ribeiro
mesh_terms: D005753:Gastric Mucosa / Q000601:surgery*; D005773:Gastroscopy; D006801:Humans; D008207:Lymphatic Metastasis; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local; D018365:Neoplasm, Residual; D013274:Stomach Neoplasms / Q000473:pathology* / Q000601:surgery*; D015996:Survival Rate