Peritoneal thickening does not necessarily mean metastasis. Clinical CT examination of the abdomen reveals that peritoneal thickening is usually seen in inflammation, cancer, etc., as follows: 1. Inflammatory diseases, such as all kinds of inflammatory infections or abdominal abscesses stimulate the local peritoneum, which can lead to inflammatory peritoneal thickening, and it is not a metastasis at this time; 2. All kinds of gastric or intestinal cancer, and the peritoneal thickening in this case should be suspected to be highly suspected of peritoneal tumor detachment, implantation, and metastasis possibility. 2, various gastric cancers or intestinal cancers, in this case, localized peritoneal thickening should be highly suspected of peritoneal tumor detachment, implantation, and metastasis, and it is usually necessary to do further abdominal enhanced CT or even PET-CT examination to make clear diagnosis. Gastrointestinal malignant tumors with peritoneal implantation and detachment usually mean that the chance of surgical radical treatment is lost. Usually, neoadjuvant chemotherapy or even transformational therapy is firstly chosen to downstage the tumor, and then according to the recovery situation to decide whether there is a chance of surgery or not.