Peritoneal carcinomatosis (peritoneal metastases)

Peritoneal carcinomatosis is a cancer of the peritoneum. The origin is usually another, more advanced cancer in the abdomen, for example stomach, colon or ovarian cancer. Because all organs are located close together in the abdominal cavity, cancer cells can very easily spread to the peritoneum.

Sometimes only limited areas of the peritoneum are affected, in other cases the cancer cells are widely scattered there and have still grown into other organs. The first signs of peritoneal cancer may be abdominal pain and constipation. Treatment for peritoneal carcinomatosis is complex: usually it consists of surgery combined with chemotherapy in the abdominal cavity.

What is peritoneal carcinomatosis?

In peritoneal carcinomatosis, cancer cells affect the peritoneum. This consists of two sheets: one lines the abdominal cavity from the inside, while the other covers the abdominal organs as protection.

Cancer cells very rarely form first on the peritoneum. In the majority of cases, its origin is advanced cancer of another organ also located in the abdomen. For example, colorectal cancer, stomach cancer or ovarian cancer often spread to the peritoneum and form cancer colonies there. Therefore, when doctors talk about peritoneal carcinomatosis or peritoneal cancer, they usually mean peritoneal metastases.

Symptoms of peritoneal carcinomatosis may include abdominal pain and constipation. If the cancer cells grow and continue to spread, more discomfort is added because the abdominal organs no longer function properly.

We usually treat peritoneal cancer with surgery combined with a heated chemotherapy solution containing powerful cytotoxins. We apply these directly into the abdominal cavity. CRS/HIPEC is the abbreviated name of the method. If their use is not possible, there are other therapeutic options. Treatments aim to relieve symptoms, extend life expectancy and improve quality of life.

Peritoneal carcinomatosis – incidence and age

The incidence of peritoneal carcinomatosis cannot be accurately quantified because peritoneal metastases can occur in many different cancers in the abdomen. Peritoneal carcinomatosis is not uncommon. This is because cancer cells can spread through the peritoneal fluid once they have made it through the original organ. In addition, many organs are located in close proximity in the abdominal cavity. Malignant tumor cells therefore have only “short distances” to travel here. The following estimates for the incidence of peritoneal metastases exist – depending on the type of cancer:

  • Approximately 15 to 20 percent of all patients with metastatic colorectal cancer have peritoneal carcinomatosis.
  • In gastric cancer, approximately 10 to 15 percent develop peritoneal metastases.
  • In ovarian cancer, about 60 to 80 percent of women have peritoneal metastases when they are first diagnosed.

A specific age cannot be given for peritoneal carcinomatosis. More generally, colorectal, gastric, ovarian or pancreatic cancers occur more frequently in older age.

Peritoneal carcinomatosis: Causes lie in another cancer

In the majority of cases, the causes of peritoneal carcinomatosis are cancer cells that have spread from another organ to the peritoneum. They often stem from tumors of the gastrointestinal tract, for example colorectal cancer, stomach cancer, pancreatic cancer or appendiceal cancer. But ovarian cancer or cervical cancer can also spread to the peritoneum. Secondary peritoneal carcinomatosis is the medical term for this. Only extremely rarely does peritoneal cancer originate directly in the peritoneum. Experts then speak of primary peritoneal carcinomatosis. An example of this is primary peritoneal mesothelioma.

Malignant tumor cells usually reach other organs via the blood and lymph channels and form cancerous metastases there. In peritoneal carcinomatosis, on the other hand, the malignant tumor cells use the peritoneal fluid that circulates freely in the abdomen. The peritoneum produces this fluid and also reabsorbs it. This provides cancer cells with an ideal “gateway” to spread throughout the abdominal cavity – including to the peritoneum.

Limited or diffuse peritoneal carcinomatosis

Experts also distinguish two forms in peritoneal carcinomatosis – depending on the extent of spread to the peritoneum:

  • Limited peritoneal carcinomatosis: The cancer cells have settled only in limited areas of the peritoneum and are confined to these areas. There are only a few, isolated tumor nodules.
  • Diffuse peritoneal carcinomatosis: Larger tumor nodules are distributed over the entire peritoneum and are also detectable on the surface of adjacent organs – this is the more common case.

Any physical illness can also be associated with psychological stress. This can manifest itself in worry, tension, circling thoughts or sleep disturbances, among other things, and can complicate the course of treatment. If you or your relatives desire psychiatric-psychological counseling and support, our specialists at the USZ will be happy to assist you.

Symptoms: Peritoneal carcinomatosis manifests nonspecifically

The symptoms of peritoneal carcinomatosis are usually nonspecific at first: abdominal pain and constipation. These complaints can occur in the context of many diseases of the gastrointestinal tract. Therefore, many people do not classify these signs as dangerous and do not pay much attention to them. Most often, they try to treat the complaints themselves first.

Man with abdominal pain

As the tumor cells grow and peritoneal carcinomatosis spreads, the organs in the abdominal cavity gradually lose their function. Then the following symptoms may appear:

  • Intestinal obstruction due to decreased bowel activity – affected individuals can no longer empty their bowels
  • Urinary retention – the filled bladder can no longer be emptied
  • Abdominal dropsy – accumulation of fluid in the abdominal cavity (ascites)
  • Loss of appetite
  • Feeling of fullness
  • Nausea and vomiting

If you are already known to have cancer and experience such symptoms, you should always consult your treating physician promptly.

Peritoneal carcinomatosis: diagnosis with us

In most cases, peritoneal carcinomatosis stems from advanced cancer in the abdomen. For example, many affected people already have a doctor who treats this tumor disease and is familiar with the patient’s medical history. Sometimes, however, doctors only find out about advanced cancer when patients come to them with complaints. We will first ask you some questions about your medical history (anamnesis), for example:

  • What exactly are your symptoms?
  • How long have the symptoms been present and how severe are they?
  • Do you have a known cancer – if so, which one? When was this diagnosed?
  • Do you have any other known medical condition?
  • Have you already undergone cancer treatment? If yes: Which one?
  • Are you taking medication for your cancer or another condition?

During a physical examination, we palpate the abdomen. We can feel the location and size of organs or detect enlarged lymph nodes. A blood test also provides information about the condition of the organs. The diagnosis of “peritoneal carcinomatosis” can be made with the aid of imaging techniques. These include:

  • Ultrasound of the abdomen (abdominal ultrasound or abdominal sonography): Ultrasound waves can be used, for example, to visualize the abdominal organs or enlarged lymph nodes.
  • Computed tomography (CT): It works with X-rays. We also use a contrast agent to visualize changes in the peritoneum such as lumps or compressions.
  • Magnetic resonance imaging (MRI = magnetic resonance imaging): Radiologists apply strong magnetic waves and virtually dissect the body into “slices. You receive high-resolution cross-sectional images from inside the body.
  • Positron emission tomography/CT(PET/CT): PET/CT shows particularly metabolically active areas, for example peritoneal metastases. In addition, it may be possible to detect a previously unknown primary tumor. We usually use the radioactively labeled sugar “18F-FDG” as the radioactive substance.

We also use laparoscopy for diagnostic purposes. This is a minimally invasive method (“keyhole surgery”) that involves small incisions. A cancer of the peritoneum can be easily recognized. In addition, the laparoscopy allows us to assess whether surgery is possible later.

Important for the subsequent treatment is how far the metastases have spread across the peritoneum and whether adjacent organs are affected. Cancer treatment also depends on this.

Peritoneal carcinomatosis: prevention, early detection, prognosis

You cannot really prevent peritoneal carcinomatosis. Peritoneal metastases usually occur in advanced cancers that are often incurable.

They are more common in stomach or colon cancer, for which there are some preventive measures: Take advantage of cancer screening examinations (e.g. colonoscopy) and pay attention to a healthy lifestyle. This includes a healthy diet, plenty of exercise, not smoking, moderate alcohol consumption and as little stress as possible. A healthy lifestyle does offer some protection against cancer, but it cannot prevent it 100 percent.

There are also no specific measures for early detection of peritoneal carcinomatosis. Regular follow-up care is important for all cancer patients. In the process, we check the state of health, record and treat complaints and search for possible metastases. Initially, close time intervals for the control examinations are advisable. Later, the time intervals extend further if no relapse is detectable.

Course and prognosis in peritoneal carcinomatosis

The course and prognosis of peritoneal carcinomatosis vary from individual to individual and cannot be generally predicted. However, the fact is that the original cancer is already more advanced when peritoneal metastases have formed. The disease is then often no longer curable.

However, the original type of cancer, how far the disease has spread and the treatment options available play a role in the course and prognosis. Some cancers are particularly aggressive, such as pancreatic and ovarian cancer. They spread rapidly, are difficult to treat, and therapies do not always respond sufficiently well.

However, this does not mean that we cannot treat peritoneal carcinomatosis and slow down its progression! There are some new therapies that can halt progression. Life expectancy is prolonged and in some cases it is even still possible to cure peritoneal carcinomatosis.

Peritoneal carcinomatosis: treatment with multiple therapies

The treatment of peritoneal carcinomatosis always belongs in the hands of several specialists from the fields of gastroentrology, oncology, gynecology, radiology and psycho-oncology. In most hospitals, these specialists work closely as a team. They discuss each case together and devise an individual treatment strategy. This is because not every therapy is equally suitable for every patient.

When choosing therapy, not only the type of original cancer and the extent of peritoneal involvement play a role, but also your age, general health, other diseases and your wishes. We usually combine several treatments to increase the effect of the therapies and life expectancy. However, it is also important to alleviate the discomfort and maintain quality of life and enjoyment of life. For this purpose, we also work together with the team of the Palliative Care Consiliary Service in the USZ to alleviate symptoms.