P1.037. Early-Onset Oesophagogastric Adenocarcinoma: Clinicopathological Characteristics and Outcomes From a Ten-Year Tertiary Centre Experience

Abstract

Abstract Topic Esophageal Cancer: Molecular Biology/Pathology Background The incidence of early-onset oesophago-gastric adenocarcinoma (EO-OGC) is rising worldwide, yet its clinicopathological characteristics and oncological outcomes remain incompletely defined. This study aimed to compare the clinical profile, treatment pathways and outcomes of patients with early-onset disease (≤55 years) and late-onset disease (>55 years) presenting with oesophago-gastric cancer. For example, early-onset gastric cancer is now the second most common early-onset gastrointestinal malignancy after colorectal cancer, underscoring the broader rise in cancer among young adults. Understanding how EO-OGC presents and behaves compared with late-onset disease is therefore increasingly important. Methods We conducted a retrospective cohort study at a UK tertiary oesophago-gastric cancer centre, identifying all patients diagnosed with oesophageal, gastro-oesophageal junction, or gastric adenocarcinoma between 2014 and 2025. Patients were stratified into early-onset (≤55 years) and late-onset (>55 years) groups. Clinicopathological data, treatment pathways, postoperative outcomes, and oncological outcomes were extracted from electronic health records. Only patients undergoing curative-intent resection were included in surgical outcome and survival analyses. Siewert type I–II tumours were classified as oesophageal and type III as gastric. Primary outcomes were disease-free survival (DFS) and overall survival (OS). Secondary outcomes included anastomotic leak, hospital-acquired pneumonia, and length of stay. Stage at diagnosis, histology, recurrence pattern, and resection margin status were also compared. Categorical variables were analysed using Chi-square or Fisher’s exact tests; continuous variables using t-tests or Wilcoxon rank-sum tests. Survival was estimated using Kaplan–Meier analysis and compared using log-rank testing. Results Among 960 patients, 162 (16.9%) had early-onset (EO) disease: 75 (46.3%) underwent curative-intent resection compared with 469/798 late-onset (LO) patients (59.4%, p = 0.004). EO patients had significantly fewer comorbidities (18.7% vs 46.3%, p < 0.00001), were more frequently female (30.9% vs 19.0%, p = 0.00014), and presented with advanced stage (p = 0.018). Diffuse gastric histology predominated in EO (65.5% vs 43.9%). EO oesophageal patients had shorter ICU stays (6.5 vs 9.4 days, p = 0.0015) and EO gastric patients had lower pneumonia rates (10.7% vs 40.3%, p = 0.00084). Despite similar postoperative stage, EO patients demonstrated significantly inferior DFS (gastric p = 0.0033; oesophageal p = 0.026), while OS did not differ. Recurrence patterns differed significantly (p = 0.00028): EO gastric cancers showed a higher rate of peritoneal spread (50.0% vs 26.3%), whereas EO oesophageal cancers recurred predominantly in solid organs (56.3% vs 66.7% in LO). Conclusion Early-onset oesophagogastric cancer is an emerging clinical entity that challenges assumptions about cancer in younger adults. Despite comparable perioperative care, these patients experience inferior disease-free survival, driven by advanced stage at presentation and intrinsically aggressive tumour biology. The predominance of diffuse and signet-ring histology, female preponderance and peritoneal recurrence patterns highlights a phenotype distinct from late-onset disease. Improving outcomes will require earlier recognition, routine biomarker testing and molecular risk stratification. Large-scale genomic and epidemiological studies are essential to clarify disease origins. Without such advances, early-onset patients will remain under-recognised and fail to realise any survival advantage youth might otherwise confer.