title: Volume-outcome relationships in pancreatoduodenectomy for cancer.
abstract: BACKGROUND
  Volume-outcome relationships in pancreatic surgery are well established, but an optimal volume remains to be determined. Studies analyzing outcomes in volume categories exceeding 20 procedures annually are lacking.
  
  
  METHODS
  A consecutive 3420 patients underwent PD for primary pancreatic or periampullary carcinoma (2005-2013) and were registered in the Netherlands Cancer Registry. Relationships between hospital volume (< 5, 5-19, 20-39 and ≥ 40 PDs/year) and mortality and survival were explored.
  
  
  RESULTS
  There was a non-significant decrease in 90-day mortality from 8.1 to 6.7% during the study period (p = 0.23). Ninety-day mortality was 9.7% in centers performing < 5 PDs/year (n = 185 patients), 8.9% for 5-19 PDs/year (n = 1432), 7.3% for 20-39 PDs/year (n = 240) and 4.3% for ≥ 40 PDs/year (n = 562, p = 0.004). Within volume categories, 90-day mortality did not change over time. After adjustment for confounding factors, significantly lower mortality was found in the ≥ 40 category compared to 20-39 PDs/year (OR = 1.72 (1.08-2.74)). Overall survival adjusted for confounding factors was better in the ≥ 40 category compared to categories under 20 PDs/year: HR (≥ 40 vs 5-19/year) = 1.24 (1.09-1.42). In the ≥ 40 category significantly more patients received adjuvant chemotherapy and had > 10 lymph nodes retrieved compared to lower volume categories.
  
  
  CONCLUSIONS
  Volume-outcome relationships in pancreatic surgery persist in centers performing ≥ 40 PDs annually, regarding both mortality and survival. The volume plateau for pancreatic surgery has yet to be determined.
authors.affiliation: Department of Research, Netherlands Comprehensive Cancer Organization (IKNL), Utrecht, The Netherlands. Electronic address: L.vanderGeest@iknl.nl.
authors.forename: Lydia G M
authors.initials: LG
authors.lastname: van der Geest
authors.affiliation: Department of Surgery, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: L Bengt
authors.initials: LB
authors.lastname: van Rijssen
authors.affiliation: Department of Surgery, Utrecht Medical Center, Utrecht, The Netherlands.
authors.forename: I Quintus
authors.initials: IQ
authors.lastname: Molenaar
authors.affiliation: Department of Surgery, Catharina Hospital, Eindhoven, The Netherlands.
authors.forename: Ignace H
authors.initials: IH
authors.lastname: de Hingh
authors.affiliation: Department of Surgery, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Bas
authors.initials: B
authors.lastname: Groot Koerkamp
authors.affiliation: Department of Surgery, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Olivier R C
authors.initials: OR
authors.lastname: Busch
authors.affiliation: Department of Research, Netherlands Comprehensive Cancer Organization (IKNL), Utrecht, The Netherlands.
authors.forename: Valery E P P
authors.initials: VE
authors.lastname: Lemmens
authors.affiliation: Department of Surgery, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Marc G H
authors.initials: MG
authors.lastname: Besselink
mesh_terms: D000368:Aged; D014670:Ampulla of Vater / Q000473:pathology / Q000601:surgery*; D016009:Chi-Square Distribution; D003138:Common Bile Duct Neoplasms / Q000401:mortality / Q000473:pathology / Q000601:surgery*; D005260:Female; D017052:Hospital Mortality; D061847:Hospitals, High-Volume; D061846:Hospitals, Low-Volume; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009426:Netherlands; D016017:Odds Ratio; D010190:Pancreatic Neoplasms / Q000401:mortality / Q000473:pathology / Q000601:surgery*; D016577:Pancreaticoduodenectomy / Q000009:adverse effects / Q000401:mortality; D016016:Proportional Hazards Models; D012042:Registries; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome