Peritoneal Carcinomatosis / Peritoneal Cancer

In most cases, peritoneal carcinomatosis does not develop as an independent primary tumor. It is usually the result of an existing cancer. Tumor cells spread into the abdominal cavity and settle on the peritoneum. This is called peritoneal metastasis.

This happens most often with tumors from the gastrointestinal tract or gynecological organs. The most common primary tumors include:

• stomach cancer
• colon cancer, especially colorectal cancer
• ovarian cancer
• pancreatic cancer
• less commonly, other tumors in the abdomen

In all these cancers, tumor cells can reach the peritoneal space directly or indirectly. They spread through the fluid in the abdomen. They can then attach to the surface of the peritoneum and form new tumor deposits there.

The actual risk factors are mainly linked to the primary tumor. These include:

• an already advanced or locally extensive cancer
• breakthrough of the tumor wall or involvement of the serosa
• aggressive growth behavior of the primary tumor
• existing spread of tumor cells into the abdomen
• certain tumor types that are more likely to cause peritoneal carcinomatosis

It is therefore important to understand that peritoneal carcinomatosis usually develops as part of an existing cancer. The risk depends less on lifestyle factors. It depends much more on the type, location and aggressiveness of the primary tumor.

Many symptoms of peritoneal carcinomatosis develop slowly. They are often quite non-specific. This is why the disease is usually found at a more advanced stage. Early symptoms often include vague abdominal discomfort, increasing pressure in the abdomen, loss of appetite, nausea and unwanted weight loss. General signs of cancer can also occur. These include exhaustion, reduced performance or so-called B symptoms. A typical sign of peritoneal carcinomatosis is ascites. This means an abnormal build-up of fluid in the abdominal cavity.

Symptoms of peritoneal carcinomatosis can include:

• increasing abdominal size
• ascites with pressure and tightness
• abdominal pain or a feeling of fullness
• loss of appetite
• nausea or vomiting
• weight loss
• tiredness, exhaustion and reduced general performance
• constipation
• shortness of breath with severe ascites
• typical symptoms of bowel obstruction

As the disease progresses, the symptoms can become more noticeable. They occur because larger tumors are present in the abdomen. Organs may be displaced, and the bowel may also be affected. Important warning signs include a new or increasing abdominal size, persistent vague abdominal symptoms, loss of appetite, unexplained weight loss or signs of ascites. If another abdominal cancer is already known, new changes in the abdomen are especially important. Pain or symptoms of bowel obstruction should also be taken seriously.

The diagnosis of peritoneal carcinomatosis is based on imaging and, if needed, tissue confirmation. Suspicion often arises when new symptoms appear in a person with known cancer. These symptoms can include increasing abdominal size, ascites, weight loss or signs of disturbed bowel movement. The key question is whether metastases can be found on the peritoneum. Doctors also assess how far the tumor has already spread inside the abdominal cavity.

CT and MRI are important imaging methods. They can show ascites, tumor deposits on the peritoneum, thickening of the peritoneum, involvement of the omentum and other affected organs. Smaller tumor deposits can be harder to detect. For this reason, the exact tumor burden cannot always be fully assessed.

If ascites is present, a puncture of the abdominal fluid is often part of the work-up. The removed fluid is then examined more closely. This can help detect free malignant cells. It is especially useful when a peritoneal tumor is suspected but cannot yet be clearly shown on imaging.

Diagnostic laparoscopy is often the most reliable way to assess peritoneal carcinomatosis. During this procedure, the abdominal cavity is examined with a small camera. Tissue samples can also be taken from suspicious areas. This histological confirmation is especially important when the diagnosis is still unclear. It can also help assess the spread of the tumor more accurately. It may support decisions about systemic, surgical or palliative treatment.

The goal of treatment is to reduce the tumor burden as much as possible. Treatment should also relieve symptoms. In some cases, a curative treatment approach may be considered. The choice of therapy depends mainly on the original tumor, the extent of metastasis, the general condition of the patient and whether the tumor deposits can be removed surgically.

An important part of treatment is cytoreductive surgery, also called CRS. The aim is to remove all visible tumor deposits from the abdomen as completely as possible. Depending on the extent of spread, an omentectomy may also be needed. This means surgical removal of the greater omentum. In selected cases, surgery is combined with HIPEC. HIPEC stands for hyperthermic intraperitoneal chemotherapy. After tumor removal, the abdominal cavity is rinsed with a heated chemotherapy solution. This is done to treat remaining microscopic tumor cells.

If complete or almost complete tumor reduction is not possible, systemic therapies may be used. These mainly include chemotherapy. Depending on the original cancer, targeted therapies or other oncological treatments may also be considered. Palliative measures also play an important role. They include treatment of ascites, symptom control for pain, nausea or constipation, and nutritional support. In advanced peritoneal carcinomatosis, treatment is not only directed against the tumor. It also focuses on relieving symptoms.

Alongside conventional medical treatment, complementary medicine is also used more often. The aim is to support the body, ease symptoms and improve quality of life during therapy. This may include acupuncture. In some cases, mistletoe therapy or selected micronutrients may also be used. In supportive oncology, exercise, acupuncture, yoga, mindfulness and relaxation methods are well studied. They may help reduce fatigue, pain, nausea, sleep problems, anxiety and inner restlessness. Oncological hyperthermia is also used as an additional physical method in some settings. The aim of this controlled heating is to support tissue blood flow and gently stimulate the immune system. In this way, it may accompany conventional cancer therapies. vitamins, minerals and trace elements may also be used in a targeted way, depending on the situation.

The prognosis and life expectancy in peritoneal cancer depend strongly on the original tumor, the spread inside the abdomen and the possible treatments. In advanced stages, tumor burden in the abdomen often increases. Severe ascites, malnutrition, bowel problems, malignant bowel obstruction and general weakness may occur. The cause of death is usually linked to the progressing cancer. It may also be related to poor food intake, infections, organ failure or complications of bowel obstruction. In this situation, palliative care is the main focus. Its aim is to relieve symptoms and maintain quality of life as much as possible.

The information listed contains relevant topics and serves to improve understanding.