VEGF-A Gene Expression Profiling in Northern Thai Gastric Cancer Patients and Potential for Anti-VEGF Therapy

Background/Objectives: Gastric cancer (GC) remains a major burden in Northern Thailand. Elevated interleukin-8 (IL-8) and vascular endothelial growth factor A (VEGF-A) expression are linked with poor prognosis and tumor progression in gastric cancer. However, the concordance of VEGF-A and IL-8 gene expression profiles and their association with chemotherapy and survival outcomes remain unclear. This study aims to characterize VEGF-A and IL-8 gene expression profiles to address these knowledge gaps. Methods: We analyzed mRNA expression of VEGF-A and IL-8 in 83 gastric mucosal tissue samples from advanced GC patients using RT-qPCR. Expression profiles were reported in distribution format, Kaplan–Meier survival curves, and multivariable Cox models to identify independent prognostic factors. Pre- and post-treatment expression patterns were observed. Results: IL-8 overexpression was found in 83.33% of patients, while VEGF-A overexpression was found in 44.23%. Baseline IL-8 and VEGF-A expression levels were not significantly associated with overall survival. However, paired sample analysis showed post-chemotherapy suppression of IL-8 and VEGF-A expression, with a small percentage of downregulation in a subgroup of patients 33.3% and 30%, respectively. Conclusions: VEGF-A and IL-8 display concordant distribution of expression patterns but differ in downregulation by the same chemotherapy regimen. Although baseline expression lacked independent prognostic value, non-frequent downregulation of VEGF-A and IL-8 occurred post-chemotherapy in Thai advanced gastric cancer patients, suggesting its potential to be a biomarker for chemoresistance. These findings support personalized molecular profiling of VEGF-A expression to identify candidates who may get the benefit from early VEGF-targeted therapies in Thai GC patients.