If Cancer Spreads to the Peritoneum

Peritoneal metastases is when cancers that started at other places in the body spread to the peritoneum or peritoneal cavity. It is different than primary peritoneal cancer that starts in the peritoneum and does not change the type of cancer you have.  (If you had colorectal cancer that has spread to your peritoneum, it is now metastatic, advanced, or stage 4 colorectal cancer.)

Since peritoneal carcinomatosis most often develops when existing cancers spread, the main risk factor is having other advanced cancers, including:

  • Appendix cancer
  • Colon cancer
  • Rectal cancer
  • Pancreatic cancer
  • Gastric cancer


Symptoms of peritoneal metastases

There may be no symptoms in the early stages, or you may have vague symptoms that resemble other conditions. In later stages, the cancer causes symptoms such as:

  • Abdominal pain
  • Bloating
  • Diarrhea, constipation, or nausea
  • Frequent urination
  • Loss of appetite or feeling full when eating
  • Weight loss or gain


Complications related to peritoneal metastases:

  • Ascites: Peritoneal metastases tend to produce fluid in the abdomen, known as ascites, which causes abdominal distension.
  • Hydronephrosis: The kidney ureters may be blocked by peritoneal metastases. This may affect the kidney function.
  • Intestinal obstruction: Peritoneal metastases may cause blockage of the intestines.


Treatment of peritoneal metastases often depends on the location and source of tumor cells. Treatment may include chemotherapy, immunotherapy, radiation, interventional radiology treatments, surgery, or a combination of these.