Annual surgeon and hospital volume of gastrectomy and gastric adenocarcinoma survival in a population-based cohort study.

BACKGROUND: It is uncertain whether centralization of gastrectomy to fewer surgeons and larger centers improves survival in gastric adenocarcinoma in Western populations. The aim of this study was to examine if higher annual surgeon or hospital volumes of gastrectomy increase gastric adenocarcinoma survival in a population-based Swedish cohort. METHODS: This study included almost all patients who underwent curatively intended gastrectomy for gastric adenocarcinoma in Sweden between 2006 and 2015 with follow-up throughout 2020. Data were collected from medical records and national registries. Annual surgeon and hospital volumes of gastrectomies were analyzed by categorization into four equal-sized groups and as continuous variables. The outcomes were 5-year all-cause mortality (main) and 5-year disease-specific mortality. Cox regression produced hazard ratios (HR) with 95% confidence intervals (95% CI), adjusted for sex, age, education, comorbidity, pathological tumor stage, pre-operative therapy, calendar period, and mutually for hospital or surgeon volume. RESULTS: The study included 1774 patients. Higher annual surgeon volume did not decrease the risk of 5-year all-cause mortality when comparing the highest and lowest quartiles (HR = 1.07, 95% CI 0.86-1.34) or when analyzed as a continuous variable (HR = 1.03, 95% 1.00-1.06). Higher annual hospital volume did not significantly decrease the risk of 5-year all-cause mortality (highest versus lowest quartiles: HR = 0.89, 95% CI 0.71-1.10; continuous variable: HR = 0.98, 95% CI 0.95-1.02). The results for 5-year disease-specific mortality were similar. CONCLUSIONS: This study, mirroring routine clinical practices in an entire Western country, indicates that neither annual surgeon volume nor annual hospital volume of gastrectomy influences the long-term survival in gastric adenocarcinoma.