405 Outcomes of Early-Onset (EO) Versus Late-Onset (LO) Oesophago-Gastric Adenocarcinoma (OGA): Insights from a Tertiary Oesophago-Gastric Centre Over a 10-Year Period

Abstract Background Early-onset-oesophago-gastric-adenocarcinoma (EO-OGA) is a growing clinical concern.We aimed to describe outcomes in EO-OGA patients compared Late-onset-oesophago-gastric-adenocarcinoma (LO-OGA) patients. Method Patients between 11/2014–12/2024 were stratified as EO-OGA (age<55years) or LO-OGA, (≥55years). Demographic, clinicopathological and outcome data were collected. Hereditary syndromes were excluded. Primary outcome was disease-free-survival(DFS); secondary outcomes included anastomotic-leak(AL), hospital-acquired pneumonia(HAP), intensive-care-unit (ICU) stay& length of stay (LOS). Survival analyses were performed using Kaplan-Meier curves. Results 135-patients had EO-OGA (24%signet-ring). EO-OGA increased from 8/year(median,2014–2018) to 16/year(median,2019–2024,p=0.082). 74 EO-OGA & 407 LO-OGA patients had curative-surgery; EO-OGA more likely to presented with advanced-stage (III/IV=78.4% vs 67.5%LO-OGA,p=0.0037); LO more likely presented with Stage I/II (32.0% vs 17.6%). AL-rates were 4.1% in EO-OGA vs.7.4% LO-OGA (p=0.45). HAP was more common in LO-Gastric-Adenocarcinoma (46% vs 11%,p = 0.0005), but comparable in oesophageal-adenocarcinoma (LO 38% vs EO 24%, p = 0.071). ICU-stay was longer in LO-oesophageal-adenocarcinoma (9.5 vs 7.0 days,p < 0.001); but comparable in gastric-adenocarcinoma (LO 5.0 vs EO 6.0 days,p = 0.54). Median EO-OGA-LOS was 10.0 days vs LO-OGA 11.0 days (p = 0.10). DFS was 85.6%, 56.0%, and 40.0% in EO-OGA vs 95.1%, 88.9%, and 84.8% in the LO-OGA group, respectively (p < 0.0001). Conclusions EO-OGA has doubled in the last decade in our unit. EO-OGA presents more advanced than LO-OGA.Short-term outcomes likely reflect improved physiological reserve; however, DFS is significantly reduced in EO-OGA.This suggests an undiagnosed aggressive tumour biology necessitating improved treatment regimes.Translational work on somatic mutational landscapes will identify potential-disease aetiology and personalised treatment strategies to improve outcomes.