SP8.13 An examination of the clinicopathological determinants of tumour regression to neoadjuvant FLOT chemotherapy in patients undergoing oesophagectomy for adenocarcinoma of the oesophagus

Aims Patients who experience a significant response to neoadjuvant FLOT chemotherapy have been reported to enjoy a better five-year survival. This service evaluation aims to determine the clinicopathological factors association with pathological tumour regression gage (TRG) in patients undergoing oesophagectomy for adenocarcinoma of the oesophagus. Methods Patients undergoing oesophgaectomy between 2018-2024 were studied. Clinicopathological factors includes demographics (age and gender), tumour stage, differentiation, and TRG, all reported by a consultant pathologist at the time of surgery. Associations were examined using chi-squared test and both log-rank and Cox regression analysis for survival. Results One hundred and fifty eight patients underwent oesophagectomy following neoadjuvant FLOT chemotherapy during the study period. 28 (16.7%) of patients experience a good response (Mandard grade 1 and 2). A higher proportion younger (<65 years) patient was observed in the poor tumour regression grade group (51.2% vs. 28.6%, p=0.027). Tumour stage, differentiation and gender were not associated with TRG. During the follow-up period, 50 patients died and median survival was not reached. On Cox proportional-hazards regression analysis, poor TRG was associated with poorer overall survival (Hazard Ratio 4.61 (95% CI 1.43-14.83; p=0.010). On multivariable regression analysis, poor TRG was not independent of ypTNM stage (HR 2.03, p<0,001) or poor differentiation (HR 1.47, p<0.001). Conclusion Poor TRG was seen more commonly in younger patients. Clinicopathological factors do not appear to be significant determinants of tumour response, and the molecular basis of chemotherapy resistance needs to be studied.