Primary gastrointestinal lymphoma is divided into four stages according to the extent of tumor invasion, and each stage is divided into two groups, A and B, according to the symptoms. Primary gastrointestinal lymphoma is a disease that originates from submucosal lymphoid tissue of the gastrointestinal tract. It is commonly caused by Helicobacter pylori infection, and is mainly manifested by fever, abdominal mass, and anemia. Gastrointestinal lymphoma is divided into 4 stages: Stage I: confined to the gastrointestinal tract (single primary or multiple non-adjacent), on the side of the diaphragm, without lymph nodes; Stage II: tumor extension to the abdomen, perigastric lymph nodes, extensive regional lymph node metastasis; Stage III: tumor invades adjacent tissues and organs, lymph node metastasis on both sides of the diaphragm; Stage IV: the tumor invades the surrounding tissues and organs, or is accompanied by the involvement of lymph nodes on the diaphragm, or distant metastasis occurs. Each stage can also be divided into two groups, A and B. Group A has no systemic symptoms, and group B has systemic symptoms, if one of the following symptoms occurs. 1. Consecutive weight loss of more than 10% without obvious reasons within 6 months before definitive diagnosis; 2. unexplained fever with temperature >38℃ for more than 3 consecutive days; 3. night sweats.