Abstract
OBJECTIVE: To determine the threshold annualized esophagectomy volume that is associated with improved survival, oncologic resection, and postoperative outcomes. BACKGROUND: Esophagectomy at high-volume centers is associated with improved outcomes; however, the definition of high-volume remains debated. METHODS: The 2004 to 2016 National Cancer Database was queried for patients with clinical stage I to III esophageal cancer undergoing esophagectomy. Center esophagectomy volume was modeled as a continuous variable using restricted cubic splines. Maximally selected ranks were used to identify an inflection point of center volume and survival. Survival was compared using multivariable Cox proportional hazards methods. Multivariable logistic regression was used to examine secondary outcomes. RESULTS: Overall, 13,493 patients met study criteria. Median center esophagectomy volume was 8.2 (interquartile range: 3.2-17.2) cases per year. On restricted cubic splines, inflection points were identified at 9 and 30 cases per year. A multivariable Cox model was constructed modeling annualized center surgical volume as a continuous variable using 3 linear splines and inflection points at 9 and 30 cases per year. On multivariable analysis, increasing center volume up to 9 cases per year was associated with a substantial survival benefit (hazard ratio: 0.97, 95% confidence interval, 0.95-0.98, P ≤0.001). On multivariable logistic regression, factors associated with undergoing surgery at a high-volume center (>9 cases per year) included private insurance, care at an academic center, completion of high school education, and greater travel distance. CONCLUSIONS: This National Cancer Database study utilizing multivariable analysis and restricted cubic splines suggests the threshold definition of a high-volume esophagectomy center as one that performs at least 10 operations a year.