title: Impact of hospital volume on long-term survival after esophageal cancer surgery.
abstract: OBJECTIVE
  The improved survival after esophageal cancer surgery in Sweden during recent years may be attributable to the increased centralization of such surgery.
  
  
  METHODS
  Population-based study.
  
  
  METHODS
  All Swedish residents undergoing esophageal cancer surgery from January 1, 1987, through December 31, 2000, were identified from the inpatient and cancer registers and were followed up until October 18, 2004, through nationwide registers. Hospital, tumor, and patient characteristics and preoperative oncological treatment were assessed through the registers and histopathological records.
  
  
  METHODS
  Among 4904 patients with esophageal cancer, 1199 patients (24.4%) who underwent resection constituted the study cohort. Main Outcome Measure Survival rates and hazard ratios (HRs) relative to hospital volume. Low-volume hospitals (LVHs) conducted fewer than 10 esophagectomies annually, while high-volume hospitals (HVHs) conducted 10 or more. Hazard ratios were adjusted for several potential confounders.
  
  
  RESULTS
  Thirty-day survival was 96% at HVHs and 91% at LVHs (P = .09). Survival rates 1, 3, and 5 years after surgery at HVHs were nonsignificantly higher (58%, 35%, and 27%, respectively) compared with those at LVHs (55%, 30%, and 24%, respectively). The adjusted HR was nonsignificantly 10% decreased at HVHs (HR, 0.90; 95% confidence interval, 0.79-1.04). In an analysis restricted to 764 patients (64%) without preoperative oncological treatment (in which the tumor stage was also adjusted for), survival was similar at HVHs and at LVHs (HR, 0.99; 95% confidence interval, 0.84-1.18).
  
  
  CONCLUSIONS
  This study revealed no effect of hospital volume on long-term survival after esophageal cancer surgery. Tumor biology apparently has a greater effect on the chances of long-term survival than hospital volume.
authors.affiliation: Unit of Esophageal and Gastric Research, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden. ioannis.rouvelas@ki.se
authors.forename: Ioannis
authors.initials: I
authors.lastname: Rouvelas
authors.forename: Mats
authors.initials: M
authors.lastname: Lindblad
authors.forename: Wenyi
authors.initials: W
authors.lastname: Zeng
authors.forename: Pernilla
authors.initials: P
authors.lastname: Viklund
authors.forename: Weimin
authors.initials: W
authors.lastname: Ye
authors.forename: Jesper
authors.initials: J
authors.lastname: Lagergren
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality / Q000473:pathology / Q000601:surgery; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000401:mortality / Q000473:pathology / Q000601:surgery; D004938:Esophageal Neoplasms / Q000401:mortality* / Q000473:pathology / Q000601:surgery; D016629:Esophagectomy; D005260:Female; D005500:Follow-Up Studies; D006785:Hospitals, University / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D011184:Postoperative Period; D012189:Retrospective Studies; D015996:Survival Rate / Q000639:trends; D013548:Sweden / Q000453:epidemiology; D016896:Treatment Outcome