The Effect of Obesity on Response to Neoadjuvant Therapy in Locally Advanced Gastric Cancer

Introduction: The effect of obesity on response to neoadjuvant chemotherapy (NACT) remains unknown. We aimed to investigate the effect of obesity on response to NACT and survival in locally-advanced gastric cancer (GC). Methods: From 2010 to 2019, 142 GC patients with clinical stage III disease who underwent curative surgery after NACT were enrolled. Patients were divided into 3 groups according to body mass index (BMI) as follows; BMI < 25 kg/m2, BMI = 25-30 kg/m2, and BMI > 30 kg/m2. The Mandard tumor regression grading system was used for tumor regression grade (TRG). Results: Of the 142 GC patients, 45(31.7%) were female. The median age was 58 years. BMI was < 25 kg/m2 in 60 (42.3%) patients, 25-30 kg/m2 in 44 (31%) patients, and > 30kg/m2 in 38 (26.8%) patients. The numbers of patients with TRGI-II, TRGIII, and TRGIV-V were 35 (24.6%), 44 (31%), and 63 (44.4%), respectively. There was no statistically significant difference among BMI groups in terms of disease-free survival (DFS) and overall survival (OS) (p = 0.919 and p = 0.398, respectively). According to TRG groups; mDFS was 46 months in TRG I-II, 28 months in TRG III, and 18 months in TRG IV-V (p <0.001). In multivariate analysis, presence of perineural invasion and lymphovascular invasion were the factors affecting TRG. Conclusion: In our study, we found that pre-treatment obesity did not affect the TRG in clinical stage III GC patients. However, a better TRG status was associated with improved survival.