In early stages, peritoneal cancer may not cause symptoms at all. Frequently, peritoneal cancer is even discovered by complete surprise during surgery for the primary tumor. Even during the asymptomatic stage, the disease may already be widespread and advanced, which supports the reputation of peritoneal cancer as a “silent killer”.

When the tumor nodules start to grow on the intestinal surface, they may cause progressive obstruction of the intestinal tract. This obstruction may result in an uncomfortable swelling of the abdomen, loss of appetite and weight, nausea and constipation. Additionally, non-specific symptoms, such as tiredness and pain, may occur.

Peritoneal carcinomatosis may also result in the accumulation of large amounts of watery fluid in the abdominal cavity. This phenomenon is called “malignant ascites” and eventually results in an enlarged abdominal cavity. For pseudomyxoma peritonei, the ascites typically consist of mucus; therefore, the name “jelly-belly” is sometimes used to describe this specific subtype. Ascites may cause symptoms similar to those of bowel obstruction, but ascites may also lead to shortness of breath due to pressure on the lungs.

Complete bowel obstruction, resulting in vomiting, abdominal pain and the inability to eat and drink, is often a late and severe symptom of peritoneal cancer and may result in rapid deterioration of the patient’s condition.