Comparison of the histopathological regression after neoadjuvant FLOT versus ECX in resectable gastroesophageal adenocarcinoma

ABSTRACT NUMBER: FEGGETTER MEDAL FOR SENIOR TRAINEES (ST3+)_3

MAIN ABSTRACT TEXT

Introduction
Neoadjuvant chemotherapy (NAC) with the FLOT regimen is increasingly used in the treatment of resectable oesophagogastric cancer (OGC). Histopathological tumour regression (TRG) is associated with a prognostic benefit. There is paucity of data on whether pathological complete response (pCR) rates between FLOT and ECX groups translate to comparable outcomes outside clinical trials. This study evaluated differences in pCR and downstaging between patients receiving neoadjuvant FLOT versus ECX.

Methods
Consecutive patients treated for OGC in a single, high-volume UK centre between 2018-2021 were reviewed. TRG was assessed by the Mandard classification with major pCR defined as TRG 1-2. A comparison of T- and N stage migration between FLOT and ECX was performed.

Results
The study included 162 patients (ECX n=84, FLOT n=78). pCR was achieved among 6 (7.1%) patients receiving ECX and 5 (6.4%) patients receiving FLOT (p=0.853). Major pCR was achieved among 11 (13.1%) receiving ECX and 12 (15.4%) receiving FLOT (p=0.677). When comparing stage migration by T-stage, 36 (42.9%) were downstaged and 6 (7.1%) patients were upstaged with ECX. Amongst FLOT patients, 42 (53.8%) were downstaged and 8 (10.3%) upstaged (p=0.189). When comparing N-stage, 29 (34.5%) achieved downstaging and 28 (33.3%) were upstaged with ECX. With FLOT, 30 (38.5%) were downstaged and 20 (25.6%) were upstaged (p=0.563).

Conclusion
There was no significant difference in pCR and stage migration rates between patients receiving neoadjuvant ECX and FLOT. pCR rates were lower than previously reported, and it is unclear if the difference in prognosis will translate into comparable clinical outcomes.