Perioperative 5‑fluorouracil, leucovorin, oxaliplatin, and docetaxel (FLOT) regimen in gastric cancer: Pathological regression grade and its relationship to clinical outcome

Background: We aimed to evaluate the data of perioperative 5-fluorouracil, leucovorin, oxaliplatin, and docetaxel (FLOT) chemotherapy regimen in locally advanced gastric cancer (LAGC) patients with real-life experience. Methods: In this retrospective study, LAGC patients who received perioperative FLOT chemotherapy regimen between 2017 and 2020 were included. The patients were grouped according to tumor regression grade (TRG): histopathological responders (complete/moderate response) and histopathological non-responders (minimal/poor response). The factors affecting TRG were evaluated and its relationship to clinical outcome was analyzed by disease-free survival (DFS) and overall survival (OS). Results: A total of 141 LAGC patients were included. Median age of patients was 62 (range: 35–75) years of whom 69.5% were men. According to TRG, 41 (29.1%) patients were histopathological responders (College of American Pathologists (CAP)-TRG 0/1). Grade, perineural and lymphovascular invasion, clinical stage, tumor markers (Carcinoembryonic antigen (CEA) and Carbohydrate antigen (CA)19-9), radiological response, and ypTNM stage were statistically significant in univariate analysis and lymphovascular invasion was detected as an independent factor in multivariate analysis for TRG. Grade 3-4 toxicities were observed in only 28 (19.9%) patients. Two years DFS and OS rates were higher in the histopathological responder group (100% and 100%) compared to the histopathological non-responder group (59% and 52.9%) (P = 0.01 and P = 0.02, respectively). Conclusion: In our study, it was found that the FLOT regimen had a favorable TRG and a safe toxicity profile in gastric cancer patients. In addition, while lymphovascular invasion could predict TRG, the survival and disease recurrence were positively affected by the favorable TRG response.