Integrative Analysis of Exosome-Mediated Single-Cell Transcriptomics and Proteomics in Gastric Cardia Cancer

This research study is collecting tissue and fluid samples from people with stomach cancer (including early and advanced stages) to study tiny particles called exosomes that cancer cells release, which may reveal information about how the cancer grows and spreads. **You may be eligible if...** - You are 18 or older - You have had an endoscopy and been confirmed to have stomach cancer (including high-grade pre-cancer, early, or advanced gastric cancer) - You are willing to provide informed consent **You may NOT be eligible if...** - You have had gastrointestinal surgery in the past year - You have undergone pre-surgery chemotherapy with cancer in a previously operated stomach - You have taken proton pump inhibitors, antibiotics, or probiotics daily in the past month - You have inflammatory bowel disease, irritable bowel syndrome, or another digestive condition that could affect the study results Talk to your doctor to see if this trial is right for you.