Peritoneal Carcinomatosis (Peritoneal Metastases)

How cancer spreads to the peritoneum

The peritoneum lines the abdominal cavity and covers the bowel, stomach, liver and other organs. Cancer cells can shed from a tumor that has grown through an organ wall, float in the small amount of fluid in the abdomen, and implant on the peritoneal surfaces. They grow as small nodules or sheets, often on the omentum (a fatty apron hanging from the stomach), the diaphragm and the bowel surface. The deposits can block lymph drainage, causing fluid buildup, and can tether or obstruct the bowel.

Common sources

Breast and lung cancers occasionally spread to the peritoneum.

Symptoms

Early peritoneal spread may cause no symptoms and is found on scans. As it progresses:

• bloating and a growing waistline
• abdominal swelling from fluid (ascites)
• abdominal pain or discomfort
• feeling full quickly, loss of appetite
• nausea and vomiting
• change in bowel habits, constipation
• weight loss and fatigue
• breathlessness when the abdomen is very swollen
• symptoms of bowel obstruction: cramping pain, vomiting, inability to pass gas or stool

Diagnosis

1. CT scan of the abdomen and pelvis; small deposits may be missed.
2. MRI and PET-CT for more detail in some cases.
3. Tumor markers such as CA-125, CEA and CA 19-9.
4. Paracentesis: removing ascites fluid with a needle for testing (cytology) and symptom relief.
5. Diagnostic laparoscopy: keyhole surgery to see the extent of disease and take biopsies. The extent is scored with the Peritoneal Cancer Index (PCI), from 0 to 39, which guides treatment decisions.
6. Biopsy and molecular testing to guide targeted therapy.

Treatment

Treatment is planned by a specialist multidisciplinary team and depends on the primary cancer, extent of spread, general health and goals.

Systemic therapy

Chemotherapy, targeted therapy and immunotherapy appropriate to the primary cancer are the foundation for most people. For ovarian cancer, combining surgery and chemotherapy is standard and often achieves long remissions.

Cytoreductive surgery and HIPEC

For selected people with limited disease, surgeons remove all visible tumor (cytoreductive surgery), sometimes including the omentum, parts of the bowel and peritoneum. This may be followed by HIPEC (hyperthermic intraperitoneal chemotherapy): heated chemotherapy circulated through the abdomen during surgery for 30 to 90 minutes to kill remaining cells. It is a major operation with significant risks and is done at specialist centers.

Best results are seen in pseudomyxoma peritonei, peritoneal mesothelioma, ovarian cancer and selected colorectal cancers with low PCI scores.

Other approaches

• PIPAC (pressurized intraperitoneal aerosol chemotherapy) is being studied.
• Intraperitoneal chemotherapy given through a port in some ovarian cancers.

Symptom and palliative care

• Paracentesis to drain ascites; an indwelling catheter can allow drainage at home.
• Managing bowel obstruction: medicines to reduce secretions and nausea, a venting tube, stents or surgery in selected cases.
• Pain control, nutrition support, and management of nausea.
• Palliative care teams help with symptoms, emotional support and planning at any stage.

Outlook

Peritoneal carcinomatosis is advanced cancer, and outlook varies widely. Untreated, survival is often measured in months. With modern systemic therapy and, for selected patients, complete cytoreductive surgery with HIPEC, some people live many years, and some with pseudomyxoma peritonei or low-volume disease are long-term survivors. A specialist center can advise on individual options.

Frequently asked questions

What is peritoneal carcinomatosis?

It is cancer that has spread to the peritoneum, the lining of the abdomen. It usually comes from cancers of the ovary, colon, stomach, appendix or pancreas, and can cause bloating, ascites, pain and bowel blockage. It is a form of advanced cancer.

What are the symptoms of peritoneal carcinomatosis?

Common symptoms are bloating, a swollen abdomen from fluid, abdominal pain, feeling full quickly, nausea, weight loss and changes in bowel habits. Vomiting with an inability to pass gas or stool suggests bowel obstruction and needs urgent care.

What is HIPEC?

HIPEC stands for hyperthermic intraperitoneal chemotherapy. After a surgeon removes all visible tumor, heated chemotherapy is circulated inside the abdomen to kill remaining cancer cells. It is used for selected patients at specialist centers and can lead to long-term control.

What is the life expectancy with peritoneal carcinomatosis?

It depends on the type of primary cancer, how widespread the disease is, response to treatment and overall health. Without treatment, survival may be months. With effective chemotherapy and, in selected cases, surgery with HIPEC, some people live for years.