Gastric cancer is the second leading cause of cancer death worldwide. Risk factors include H. pylori infection, smoking, and diet low in fruits and vegetables. Genetic factors include certain gene mutations. Symptoms often include abdominal discomfort and weight loss. Diagnosis involves endoscopy with biopsy. Staging uses TNM classification and involves assessing tumor invasion and lymph node metastasis. Treatment depends on stage but commonly includes surgery such as gastrectomy with lymph node dissection, as well as chemotherapy and radiation therapy. Palliative options are used for advanced disease.