In 2007, Cancer Care Ontario created Thoracic Surgical Oncology Standards for the delivery of surgery including lobectomy, esophagectomy and pneumonectomy. These standards regionalized thoracic surgery into designated centers and mandated physical and human resources. This analysis seeks to identify the impact of these standards, hereafter referred to as "regionalization", on outcomes after thoracic oncology surgery in Ontario, Canada. Population-level analysis of patients undergoing lobectomy, esophagectomy or pneumonectomy, using multi-level regression models to compare 30- and 90-day mortality and length of stay length of stay, before, during and after regionalization. Interrupted time series models were used to assess for an impact of regionalization, controlling for ongoing trends. A total of 22,195 surgeries (14,902 lobectomies, 4,958 esophagectomies, and 2,408 pneumonectomies) were performed within the study period. >99% of cases were performed at a designated center post-regionalization. Mean annual volumes per designated center increased post-regionalization for lobectomy and esophagectomy, and decreased for pneumonectomy. 30- and 90-day mortality and length of stay improved for lobectomy and esophagectomy over the study period, as did 90-day mortality for pneumonectomy. However, the interrupted time series analysis did not demonstrate any statistically significant effect of regionalization on these outcomes, separate from pre-existing trends. Consistent improvements in mortality and length of stay in thoracic surgical oncology occurred on a provincial level between 2003-2020, although this analysis does not attribute these improvements to implementation of Thoracic Surgical Oncology Standards including regionalization.