Is treatment delivery of perioperative FLOT therapy in locally advanced OGA associated with recurrence-free survival?

391 Background: Although perioperative FLOT therapy is a standard for locally advanced oesophagogastric adenocarcinoma (LA-OGA), completing all cycles, especially in the adjuvant chemotherapy (ACT) phase, is often challenging. This study examined the survival impact of treatment delivery in LA-OGA patients receiving FLOT therapy. Methods: 423 patients who underwent radical resection at The Royal Marsden Hospital from 2017 to 2023 were screened. Major inclusion criteria included patients with LA-OGA (cT2≤ and Nany or Tany and N+), treated with FLOT (at least one cycle of neoadjuvant chemotherapy) and radical resection, with an ECOG performance status of 0–2. Patients were divided into therapy incomplete (Tx Incomp, less than eight cycles of FLOT) and therapy (Tx comp) groups. We performed univariate and multivariate analyses, as well as propensity score matching (PSM) analysis, to evaluate whether treatment delivery was associated with recurrence-free survival (RFS) and overall survival (OS). Kaplan-Meier curves and restricted mean survival times (RMST) up to 36 months were used to evaluate the survival time. The primary endpoint was the 3-year RFS and OS rate. Results: Of the screened patients, 210 met the inclusion criteria, with 79 (38%) in the Tx Incomp and 131 (62%) in the Tx comp group, and 50 (24%) patients did not receive ACT. The median follow-up time was 26.5 months. The 3-year RFS and OS rates in the Tx Incomp and Tx comp groups after PSM were 54% vs 59% (p=0.14) (RMST difference: 4.04 months, p=0.09) and 58% vs 78% (p=0.04) (RMST difference: 6.15 months, p<0.001), respectively. Multivariable analysis showed a significant impact of Tx comp on OS (HR 0.53, 95% CI: 0.32-0.88). In the subgroup of ypN-positive patients, a significant difference of RMST in OS rate was observed between those who started ACT and those who did not start ACT (RMST difference: 7.89 months, p=0.01), whereas no significant difference was found in the ypN-negative group (RMST difference: 0.65 months, p=0.75). Conclusions: This study suggests that completing FLOT therapy is associated with better OS. The impact of ACT might differ according to ypN stage.