Peritoneal cancer, also known as peritoneal tumor, is caused by the following reasons: 1) there are tumors originating from the peritoneum, i.e. primary peritoneal cancer; 2) there are metastatic tumors, i.e. metastatic peritoneal cancer, more commonly known as mucinous cancer from appendix, which can metastasize to the peritoneum; those originating from stomach are called gastric cancer, which can metastasize to the peritoneum; those originating from colon cancer and rectal cancer can also metastasize to the peritoneum; some female patients originate from Some female patients have gynecological tumors, such as ovarian cancer and cervical cancer, which can also metastasize to the peritoneum. In conclusion, peritoneal cancer is primary peritoneal cancer that originates from the peritoneum, and metastatic peritoneal cancer is called metastatic peritoneal cancer.