Pathological response guides adjuvant 5-fluorouracil, leucovorin, oxaliplatin, and docetaxel (FLOT) chemotherapy in surgically resected gastro-oesophageal cancer (SPACE-FLOT): international cohort study

BACKGROUND: Many patients with locally advanced gastro-oesophageal cancers are unable to complete adjuvant 5-fluorouracil, leucovorin, oxaliplatin, and docetaxel (FLOT) chemotherapy, raising questions about its therapeutic utility. The aim of this study was to examine whether pathological response to neoadjuvant FLOT can guide its adjuvant use. METHODS: Patients with non-metastatic gastro-oesophageal adenocarcinoma who received neoadjuvant FLOT and underwent surgery from 1 January 2017 to 1 January 2022 from 43 hospitals across 12 countries were analysed. Pathological response was assessed using tumour regression grading systems, trichotomized into minimal responders (MR; worst category), complete responders (CR; pCR), and partial responders (PR; between MR and CR). Survival outcomes of patients who did and did not receive adjuvant FLOT were compared using Kaplan-Meier, Cox regression, propensity score matched, and sensitivity analysis. RESULTS: A total of 1887 patients (459 MR, 221 CR, and 1207 PR) were evaluated. The median follow-up was 25.5 (interquartile range 15.0-39.1) months. In the MR group, there was no difference in disease-free survival (DFS; HR 1.03 (95% c.i. 0.78 to 1.36), P = 0.836) between those who did and did not receive adjuvant FLOT. Whilst there was a difference in non-adjusted OS, this became statistically non-significant after adjusting for baseline characteristics (HR 0.96 (95% c.i. 0.70 to 1.30), P = 0.801). In the CR group, there was no difference in DFS (HR 0.88 (95% c.i. 0.41 to 1.85), P = 0.724) or OS (HR 0.69 (95% c.i. 0.31 to 1.54), P = 0.343) between those who did and did not receive adjuvant FLOT. In the PR group, adjuvant FLOT conferred a significant DFS (HR 0.68 (95% c.i. 0.55 to 0.86), P < 0.001) and OS (HR 0.55 (95% c.i. 0.44 to 0.69), P < 0.001) benefit. CONCLUSION: Pathological response to neoadjuvant FLOT may guide the use of adjuvant FLOT, enabling personalized approaches to treatment.