Technical comment on: Güller et al. Lower hospital volume is associated with higher mortality after oesophageal, gastric, pancreatic and rectal cancer resection.

BACKGROUND In various countries, the association of lower hospital volume and higher mortality after oesophageal, gastric, pancreatic and rectal cancer resection has been clearly demonstrated. However, scientific evidence regarding the volume-outcomes relationship for high-risk visceral surgical procedures in Switzerland is lacking. The a priori hypothesis of this retrospective population-based cohort study analysis was that low-volume hospitals in Switzerland have a higher rate of postoperative mortality after oesophageal, gastric, pancreatic and rectal cancer resection. METHODS Patients undergoing elective resection of oesophageal, gastric, pancreatic and rectal cancer between 1999 and 2012 were identified in the inpatient database of the Swiss Federal Statistical Office. Nonparametric correlation analyses were used to assess time trends. Mortality was assessed in univariable and risk-adjusted conditional logistic regression analyses with stratification for year of surgery. RESULTS A total of 1487 oesophageal, 4404 gastric, 2668 pancreatic and 9743 rectal cancer patients were identified. For all cancer entities, significant treatment centralisation was observed over the time period (all p <0.001). The rate of mortality was inversely related to the annual number of patients treated at a certain hospital. The decrease of postoperative mortality from low-volume to high-volume hospitals was 6.3% to 3.3% for oesophageal cancer (p = 0.019), 4.9% to 3.3% for gastric cancer (p = 0.023), 5.4% to 2.0% for pancreatic cancer (p = 0.037), and 2.4% to 1.6% for rectal cancer (p = 0.008). These results were confirmed in risk-adjusted analyses with a decreased odds of pos-operative death by 49% for oesophageal (odds ratio [OR] 0.51, 95% confidence interval [CI] 0.22-1.18; p = 0.085), 32% for gastric (OR 0.68, 95% CI 0.48-0.98; p = 0.032), 68% for pancreatic (OR 0.32, 95% CI 0.11-0.89; p = 0.011) and 29% for rectal cancer (OR 0.71, 95% CI 0.52-0.98; p = 0.033). CONCLUSION This population-based analysis - the first of its kind in the literature - demonstrates a higher postoperative mortality in low-volume hospitals for patients undergoing oesophageal, gastric, pancreatic and rectal cancer resection in Switzerland. Hence, such operations should preferably be performed in high-volume hospitals.