IntroductionAt a national level, understanding preventable mortality after oesophago-gastric cancer surgery can direct quality-improvement efforts. Accordingly, utilizing the Australian and New Zealand Audit of Surgical Mortality (ANZASM), we aimed to: (1) determine the causes of death following oesophago-gastric cancer resections in Australia, (2) quantify the proportion of potentially preventable deaths, and (3) identify clinical management issues contributing to preventable mortality.MethodsAll in-hospital mortalities following oesophago-gastric cancer surgery from 1 January 2010 to 31 December 2020 were analysed using ANZASM data. Potentially preventable and non-preventable cases were compared. Thematic analysis with a data-driven approach was used to classify clinical management issues.ResultsOverall, 636 complications and 123 clinical management issues were identified in 105 mortalities. The most common causes of death were cardio-respiratory in aetiology. Forty-nine (46.7%) deaths were potentially preventable. These cases were characterized by higher rates of sepsis (59.2% vs 33.9%,p= 0.011), multiorgan dysfunction syndrome (40.8% vs 25.0%,p= 0.042), re-operation (63.3% vs 41.1%,p= 0.031) and other complications compared with non-preventable mortality. Potentially preventable mortalities also had more clinical management issues per patient [median (IQR): 2 (1–3) vs 0 (0–1),p< 0.001), which adversely impacted preoperative (30.6% vs 7.1%,p= 0.002), intraoperative (18.4% vs 5.4%,p= 0.037) and postoperative (51.0% vs 17.9%,p< 0.001) care. Thematic analysis highlighted recurrent areas of deficiency with preoperative, intraoperative and postoperative patient management.ConclusionsAlmost 50% of deaths following oesophago-gastric cancer resections were potentially preventable. These were characterized by higher complication rates and clinical management issues. We highlight recurrent themes in patient management to improve future quality of care.Supplementary InformationThe online version contains supplementary material available at 10.1245/s10434-023-13571-8.