Cancer is a generic term for malignant tumors, and ascites is a common clinical manifestation of advanced cancer patients. The causes of ascites in advanced cancer patients are considered as follows: 1. Lymphatic tract, bloodstream and implantation spread invade the peritoneum in advanced cancer, thus causing direct damage to lymphatic and venous channels and increasing the passage of peritoneal vasculature leading to the formation of ascites. 2. The formation of ascites can be caused by the blockage of lymphatic and venous drainage, which affects the balance of protein drainage in ascites. 3. Patients with advanced cancer have low immunity and are prone to complications of infection, which can cause reactive peritonitis and lead to the formation of ascites. 4. Patients with advanced cancer have a significantly lower diet and poor health condition, which leads to hypoproteinemia and can also lead to the formation of ascites.