Purpose: We aimed to identify the presence and length of esophagectomy proficiency gain curves in terms of short- and long-term mortality for esophageal cancer., Patients and Methods: Patients who underwent esophagectomy for esophageal cancer between 1987 and 2010 with follow-up until 2014 were identified from a well-established, population-based, nationwide Swedish cohort study. Proficiency gain curves were created by using risk-adjusted cumulative sum analysis for 30-day, 90-day, 1-year, 3-year, and 5-year all-cause and disease-specific mortality measures. Similarly, the proficiency gain curves for lymph node harvest, resection margin status, and reoperation incidence were assessed as performance-contributing factors to the observed changes in long-term survival., Results: Esophagectomies in 1,821 patients with esophageal cancer were conducted by 139 surgeons. The change-point in proficiency gain curve for all-cause 30-day mortality was early, at 15 cases, when mortality decreased from 7.9% to 3.1% (P < .001). Later change-points, which ranged from 35 to 59 cases, were observed for 1-, 3- and 5-year mortality rates, for which all-cause mortality decreased from 34.9% to 27.7% (P = .011), from 47.4% to 41.5% (P = .049), and from 31.4% to 19.1% (P = .009), respectively. Similar change-points were observed in disease-specific mortality at 1 and 3 years. There was a continuous increase in lymph node harvest, which did not plateau. Also, change-points were observed for resection margin with tumor involvement at 17 cases, with a reduction from 20.9% to 15.2% (P = .004), and for reoperation rate at 55 cases, with a reduction from 12.6% to 5.0% (P < .001)., Conclusion: The gain of proficiency in esophagectomy for cancer is associated with measurable changes in short- and long-term mortality results. These findings indicate a need for structured national training and mentorship programs for esophageal cancer surgery., (© 2016 by American Society of Clinical Oncology.)