BACKGROUND: The National Oesophago-Gastric Cancer Audit (NOGCA) captures patient data from diagnosis to end of primary treatment for all patients with oesophagogastric (OG) cancer in England and Wales. This study assessed changes in patient characteristics, treatments received, and outcomes for OG cancer surgery for the period 2012-2020, and examined which factors may have led to changes in clinical outcomes over this time. METHODS: Patients diagnosed with OG cancer between April 2012 and March 2020 were included. Descriptive statistics were used to summarize patient demographics, disease site, type, and stage, patterns of care, and outcomes over time. The treatment variables of unit case volume, surgical approach, and neoadjuvant therapy were included. Regression models were used to examine associations between surgical outcomes (duration of stay and mortality), and patient and treatment variables. RESULTS: In total, 83 393 patients diagnosed with OG cancer during the study period were included. Patient demographics and cancer stage at diagnosis showed little change over time. Altogether, 17 650 patients underwent surgery as part of radical treatment. These patients had increasingly more advanced cancers, and a greater likelihood of pre-existing comorbidity in more recent years. Significant decreases in mortality rates and duration of stay were noted, along with improvements in oncological outcomes (nodal yields and margin positivity rates). Following adjustment for patient and treatment variables, increasing audit year and trust volume were associated, respectively, with improved postoperative outcomes: lower 30-day mortality (odds ratio (OR) 0.93 (95 per cent c.i. 0.88 to 0.98) and OR 0.99 (95 per cent c.i. 0.99-0.99)) and lower 90-day mortality (OR 0.94 (95 per cent c.i. 0.91 to 0.98) and OR 0.99 (95 per cent c.i. 0.99-0.99)), and a reduction in duration of postoperative stay (incidence rate ratio (IRR) 0.98 (95 per cent c.i. 0.97 to 0.98) and IRR 0.99 (95 per cent c.i. 0.99 to 0.99)). CONCLUSION: Outcomes of OG cancer surgery have improved over time, despite little evidence of improvements in early diagnosis. The underlying drivers for improvements in outcome are multifactorial.