P1.036. Early-Onset Gastric Cancer (EOGC): A Meta-Analysis of Risk Factors, Clinicopathological Features, and Survival Outcomes

Abstract

Abstract Topic Esophageal Cancer: Other Background Early onset gastric cancer (EOGC), defined as diagnosis before 55 years, represents a growing global health challenge. Although traditionally rare, its incidence is rising and now constitutes the second most common early onset gastrointestinal malignancy after colorectal cancer. EOGC has been hypothesised to reflect distinct biology, yet risk factors, clinicopathological features and survival outcomes remain poorly synthesised. We aimed to evaluate global evidence on EOGC and, where possible, compare findings with late onset gastric cancer to determine whether EOGC represents a distinct clinical entity with implications for earlier diagnosis and targeted prevention strategies. Methods A systematic review and meta-analysis was conducted according to PRISMA guidelines. PubMed, Embase and Scopus were searched from inception to 20 June 2025. After deduplication, titles, abstracts and full texts were screened for eligibility. Studies were included if they reported EOGC (<55 years) as a distinct cohort and provided extractable data on risk factors, clinicopathological characteristics or overall survival. Comparative late-onset cohorts were included when available. Case reports, reviews, studies without age stratification, mixed-malignancy cohorts and studies lacking sufficient numerical data were excluded. Non-English studies were excluded unless reliable translation was possible. Effect estimates were extracted or calculated, and pooled using random-effects models. Heterogeneity was assessed using I2 statistics. Survival proportions were synthesised where comparable time points could be extracted. Results Ninety-one studies comprising 30,067 EOGC patients were included. EOGC showed a significant female predominance globally (53.3% vs 46.7%; p < 0.0001), and women were more likely to have EOGC than late-onset disease (OR 1.50, 95% CI 1.45–1.56). Significant associations were identified for Helicobacter pylori (OR 4.12, 2.37–7.18), family history (OR 4.02, 3.03–5.36), high salt intake (OR 2.06, 1.44–2.94) and obesity (OR 1.81, 1.58–2.07), while smoking and alcohol were not associated. Diffuse-type and signet-ring morphology were prominent (38.9%). EOGC more frequently presented at advanced stage than late-onset cancer (52.5% vs 45.9%; p < 0.0001). Pooled overall survival was 78.0% at 1 year, 51.1% at 3 years and 43.0% at 5 years, with no significant difference compared with late-onset disease (OR 1.08, 0.39–2.97; p = 0.88). Distal gastric cancers predominated across all global regions, but the highest burden of proximal tumours was observed in East and South-East Asia. Conclusion EOGC exhibits a distinct clinicopathological and risk-factor profile, characterised by strong associations with H. pylori, family history, high-salt diet and obesity, alongside a high burden of diffuse and signet-ring histology. Despite younger age, advanced-stage presentation is common and long-term survival remains poor, with outcomes comparable to older adults. These findings indicate that youth does not confer prognostic advantage and support the need for targeted prevention, earlier recognition and tailored research efforts focused on gastric cancer in younger populations.