title: Hospital and surgeon volume in relation to survival after esophageal cancer surgery in a population-based study.
abstract: OBJECTIVE
  The influence of hospital and surgeon volume on survival after esophageal cancer surgery deserves clarification, particularly the prognosis after the early postoperative period. The interaction between hospital and surgeon volume, and the influence of known prognostic factors need to be taken into account.
  
  
  METHODS
  A nationwide Swedish population-based cohort study of 1,335 patients with esophageal cancer who underwent esophageal resection in 1987 to 2005, with follow-up for survival until February 2011, was conducted. The associations between annual hospital volume, annual surgeon volume, and cumulative surgeon volume and risk of mortality were calculated with multivariable parametric survival analysis, providing hazard ratios (HRs) with 95% CIs. HRs were mutually adjusted for the surgery volume variables and further adjusted for the prognostic factors age, sex, comorbidity, calendar period, tumor stage, tumor histology, and neoadjuvant therapy.
  
  
  RESULTS
  There was no independent association between annual hospital volume and overall survival, and hospital volume was not associated with short-term mortality after adjustment for hospital clustering effects. A combination of higher annual and cumulative surgeon volume reduced the mortality occurring at least 3 months after surgery (P trend < .01); the HR was 0.78 (95% CI, 0.65 to 0.92) comparing surgeons with both annual and cumulative volume above the median with those below the median. These results remained when hospital and surgeon clustering were taken into account.
  
  
  CONCLUSIONS
  Because surgeon volume rather than hospital volume independently influences the prognosis after esophageal cancer surgery, centralization of this surgery to fewer surgeons seems warranted.
authors.affiliation: Unit of Upper Gastrointestinal Research, Karolinska Institutet, NS 67, Level 2, SE-171 76 Stockholm, Sweden. maryam.derogar@ki.se
authors.forename: Maryam
authors.initials: M
authors.lastname: Derogar
authors.forename: Omid
authors.initials: O
authors.lastname: Sadr-Azodi
authors.forename: Asif
authors.initials: A
authors.lastname: Johar
authors.forename: Pernilla
authors.initials: P
authors.lastname: Lagergren
authors.forename: Jesper
authors.initials: J
authors.lastname: Lagergren
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D015897:Comorbidity; D004938:Esophageal Neoplasms / Q000401:mortality* / Q000473:pathology / Q000601:surgery*; D016629:Esophagectomy / Q000706:statistics & numerical data*; D005260:Female; D006761:Hospitals / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009026:Mortality / Q000639:trends; D015999:Multivariate Analysis; D016017:Odds Ratio; D010820:Physicians / Q000706:statistics & numerical data*; D011379:Prognosis; D012042:Registries; D018570:Risk Assessment; D012307:Risk Factors; D016019:Survival Analysis; D013548:Sweden / Q000453:epidemiology; D013997:Time Factors; D016896:Treatment Outcome