398 Early-Onset Gastric Cancer (EOGC): A Meta-Analysis of Disease Presentation and Survival

Abstract Background Gastric Cancer (GC) has a poor 5-year overall survival(OS). The incidence is declining, but there is a worrisome increase of EOGC (age<55years) that warrants urgent investigation. Method A literature search was performed using terms including “early-onset gastric cancer,” “gastric adenocarcinoma,” “survival,” “incidence,” and “clinicopathological characteristics”. Studies reporting primary outcomes (1-, 3-, and 5-year survival) and secondary outcomes (clinicopathological characteristics, global distribution / risk factors) were included. Results 81 studies were included (53 East-Asia, 12 North-America, 11 Europe, 3 South-Asia, 2 West-Asia,n=18,138). 51.2% EOGC cases were female. Global incidences (sparsely reported) corresponded to declining EOGC (1990-2015), followed by an increase of +1.39%/year/average. Signet-rings was present in 38.9%. Presenting complaints included: abdominal pain (60.7%), weight loss (20.4%), nausea (18.2%). 31% EOGC was PDL-1 positive. Germline variants only accounted for 2.4% EOGC-cases. Advanced-stage at presentation was more common in EOGC (35.9%, n = 2,344 vs 34.5% LO, n = 12,241). Stage III was more common in EO (p = 0.038); stage IV was more common in EO (15.7%, compared to LO 11.3%, p < 0.0001). Meta-analysis showed pooled EO-OS as: 1-year=78%, 3-years=51%, 5-years=43%. LOGC had comparable 5-year OS of 40.4%. Conclusions EOGC appears to be a unique pathological entity warranting further investigation. The aggressive presentation necessitates awareness and early detection. Concerningly, individuals have a comparable long-term survival to LOGC counterparts, implying disease recurrence as a potential life-limiting factor. Current work is aimed at delineating tumour location and risk factors. There is an unmet need to understand aetiology and tumour biology to tailor management, surveillance& improve EOGC outcomes.