title: Impact of subcentimeter margin on outcome after hepatic resection for colorectal metastases: a meta-regression approach.
abstract: BACKGROUND
  The optimal margin width and its influence on outcomes after hepatic resection for colorectal liver metastases is still controversial: a meta-analysis was conducted to analyze the impact of subcentimeter margin width on patient and disease-free survival after resection.
  
  
  METHODS
  A systematic search was performed, covering the last decade, following the Meta-analysis Of Observational Studies in Epidemiology guidelines. Relative risks (RRs) for patient and disease-free survival (DFS) were calculated after resection in relationship to a margin width >1 cm (R0 > 1 cm) and between 1 mm and 1 cm (R0 < 1 cm) using the DerSimonian and Laird random-effects model. Meta-regression was applied for covariate adjustment.
  
  
  RESULTS
  Eleven observational studies were identified involving 2823 patients. Overall, 59.1% of patients were R0 < 1 cm and 40.9% were R0 > 1 cm. Meta-analysis showed that compared with patients with margins R0 > 1 cm, a R0 < 1 cm margin lead to decreased 1-, 3-, and 5-year DFS with a RR of 1.17 (95% confidence interval [CI] 1.07-1.27), 1.38 (95% CI 1.16-1.65), and 1.55 (95% CI 1.25-1.91), respectively, but patient survival was obviously affected (P > .05 in all cases). Patients with margins of R0 < 1 cm differ from those with R0 > 1 cm for greater proportions of multiple metastases (RR 1.43; 95% CI 0.25-1.61) and synchronous bowel disease (RR 1.42; 95% CI 0.8-1.92). Meta-regression showed that these two covariates had a significant impact on DFS but not on patient survival.
  
  
  CONCLUSIONS
  A resection margin width >1 cm is desirable even if patient survival is at best only slightly affected by subcentimeter margin as a consequence of a decreased DFS. The presence of multiple metastases and synchronous bowel neoplasm represent potential study selection biases that significantly decrease DFS; well-conducted, matched analyses consequently are essential to clarify the issue.
authors.affiliation: Liver and Multiorgan Transplant Unit, S. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy. aleqko@libero.it
authors.forename: Alessandro
authors.initials: A
authors.lastname: Cucchetti
authors.forename: Giorgio
authors.initials: G
authors.lastname: Ercolani
authors.forename: Matteo
authors.initials: M
authors.lastname: Cescon
authors.forename: Eleonora
authors.initials: E
authors.lastname: Bigonzi
authors.forename: Eugenia
authors.initials: E
authors.lastname: Peri
authors.forename: Matteo
authors.initials: M
authors.lastname: Ravaioli
authors.forename: Antonio D
authors.initials: AD
authors.lastname: Pinna
mesh_terms: D015179:Colorectal Neoplasms / Q000401:mortality / Q000473:pathology*; D006498:Hepatectomy / Q000379:methods*; D006801:Humans; D008113:Liver Neoplasms / Q000401:mortality / Q000556:secondary / Q000601:surgery*; D012044:Regression Analysis; D016019:Survival Analysis; D016896:Treatment Outcome