5PSQ-026 Comparison of perioperative chemotherapy and preoperative chemoradiotherapy in gastroesophageal junction adenocarcinoma: analysis from the AGAMENON-SEOM registry

<h3>Background and Importance</h3> The optimal curative strategy for gastroesophageal junction adenocarcinoma (GEJA) is unknown. <h3>Aim and Objectives</h3> This study compares perioperative chemotherapy (CT) with preoperative chemoradiotherapy (CRT) in GEJA treatment. <h3>Material and Methods</h3> From the AGAMENON-SEOM registry, 1893 patients had localised gastroesophageal adenocarcinoma, and of those, the ones with GEJA who were treated with preoperative CRT or perioperative CT were included. <h3>Results</h3> Among the 285 GEJA patients diagnosed between 2009 and 2023, 77% (n=220) received perioperative CT, and 23% (n=65) received preoperative CRT. The median age was 64 years (range 34–91), 20% (n=57) were women, and 95% (n=271) had an ECOG performance status of 0–1. Patient characteristics and outcomes are summarised in table 1. Siewert III cancers were more common in the perioperative CT group (34%), while Siewert I cancers predominated in the CRT group (41%). Surgery was performed in 92% of CT-treated and 85% of CRT-treated patients, with R0 resection rates of 78% and 79% and complete pathological responses of 9% and 16%, respectively. Four percent did not complete preoperative CRT, while 32% did not start postoperative CT. Recurrence occurred in 31% of patients treated with perioperative CT and 36% with CRT. Recurrence patterns for perioperative CT were distant (19%), local (7%), and mixed (5%), while for CRT were distant (29%), local (0%), and mixed (7%). Distant recurrence was more frequent with CRT (p&lt;0.005). Severe postoperative complications occurred in 15%, and lethal complications in 4%, with no differences between treatments. Overall survival was 53 vs. 41 months (HR 0.77; 0.72–0.90; p=0.043) and disease-free survival was 34 vs. 29 months (HR 0.85; 0.83–1.15; p=0.661) for CT vs. CRT. <h3>Conclusion and Relevance</h3> For GEJA T2–4 or N+ M0, perioperative CT was associated with fewer distant metastases and improved overall survival compared to neoadjuvant CRT. <h3>References and/or Acknowledgements</h3> <h3>Conflict of Interest</h3> No conflict of interest