Gastric cancer is the 3rd cause of cancer-related death around the world. Its high mortality rate is due to frequent diagnosis at advanced stages and few treatment options. Metabolomics is a recent approach used in oncology to improve the molecular understanding of cancer through metabolite profile study. In this work, our objective was to analyze the metabolic profile of gastric adenocarcinoma patient's tissues using mass spectrometry. For this, we collected fresh tissue samples of the tumor, resection margins, and metastasis from surgery biopsies; then, 25 mg of tissue was macerated and submitted to extraction with methanol for 18 hours. The samples were analyzed by direct infusion in a TSQ QuantumTM (Thermo-Scientific) using electrospray ionization in positive ion mode full-scan (ESI+). The data analysis consisted of a Principal Component Analysis (PCA) and a Hierarchical Cluster Analysis (HCA). In our results, samples showed great peak intensity between 600-900 m/z region (figure 1). The hypothesis for this can be the presence of glycerophospholipids, molecules related to energy production and energy metabolism that might be associated with cell proliferation, a hallmark of cancer progression. In PCA analysis, the sample groups were distinguished (figure 2). In HCA analysis, the results also show the tissue types being effectively differentiated (figure 3). Additionally, the tumor and metastasis samples clustered, suggesting metabolic similarities between the primary tumor and the secondary tumor sites. Thus, complementary analyzes are needed to identify the main discriminating compounds. Therefore, metabolomic analysis
using mass spectrometry, even at low resolution, can be a potential tool to improve the molecular understanding of gastric cancer.