P-75 Retrospective Comparison Between FLOT Perioperative Chemotherapy Vs Surgery Followed by Adjuvant Chemotherapy: Results from a Multicenter Analysis

Most guidelines concerning patients with not-metastatic gastric cancer, particularly in western countries, suggest that perioperative chemotherapy with FLOT regimen should be considered the standard of care. Albeit FLOT proves to be more effective compared with ECX/ECF, there is a lack of data comparing patients treated with this strategy versus surgery followed by adjuvant chemotherapy. We conducted a retrospective analysis with the aim of identifying whether there are factors that might reduce perioperative FLOT effectiveness compared with surgery followed by adjuvant chemotherapy. We conducted a retrospective, multicenter analysis concerning relapse-free survival (RFS) in patients who received perioperative chemotherapy with FLOT regimen for gastric cancer amenable to surgery. Patients had either cT3 (or worse) and/or cN+ stage. RFS was calculated by Kaplan-Meier method and stratification variables were tumour histology (intestinal vs diffuse type), cT stage (cT4 vs cT3), cN stage (cN+ vs cN0). We compared RFS of this group of patients with a historical control group of patients who received surgery followed by adjuvant chemotherapy. Patients were selected by inverse probability matching method (NEAREST method); variables used for matching were the same stratifying factors used in the primary analysis (cT stage, cN stage, histology). Log-rank test was used to assess differences among the strata whereas multivariate analysis was performed by Cox-proportional hazard regression. All analyses were performed with a level of statistical significance (p) set at 0.05. 27 patients were enrolled. 15/27 (55%) had diffuse-type cancer, 15/27 (55%) had cT4 stage and 23/27 (85%) had cN+ stage. Median follow-up time was 2 years. During this follow-up time, 8 patients (29%) relapsed. Median RFS of the whole group was 17.16 months. There was either a higher risk of relapse or shorter RFS for cN+ (HR:1.70, p=0.53) and cT4 stage (HR:3.90, p=0.06), but it was not statistically significant. Diffuse-type histology was associated with significantly worse RFS (HR:6.99, p=0.01). Multivariate analysis confirmed an independent prognostic role of diffuse-type histology (Exp(B):9.97, p=0.04). Matching analysis sorted out 129 patients that could be compared from a previous historical group of 477 patients who received surgery followed by adjuvant chemotherapy. There was no difference in RFS between the two groups (HR:0.94, p=0.86). When diffuse-type histology was used as means to stratify different treatment options (perioperative vs adjuvant), a statistically significant difference in terms of RFS was proven: diffuse-type histology treated with perioperative FLOT chemotherapy seemed to have worse survival compared with diffuse-type histology treated with adjuvant chemotherapy (HR:2.39, p=0.02). To our knowledge, this is the first analysis comparing outcomes for patients treated with perioperative FLOT vs patients treated with surgery followed by adjuvant chemotherapy. Our results suggest that patients who receive perioperative FLOT have similar survival outcomes compared with patients who receive surgery and are able to receive adjuvant chemotherapy. However, tumour histology might determine differences in outcome on the basis of the selected treatment strategy, suggesting that FLOT might be at reduced effectiveness, compared with surgery followed by adjuvant therapy, when diffuse-type histology is present.