Peritoneal carcinomatosis is a serious condition that happens when cancer spreads to the lining of the abdomen, called the peritoneum. Peritoneal carcinomatosis usually comes from cancers that start in other organs, such as the colon, stomach or ovaries. Peritoneal carcinomatosis is usually a sign that the cancer is at a late stage.

Peritoneal carcinomatosis can cause belly pain and swelling, blockage in the bowels, and loss of appetite. Treatments for this condition include chemotherapy, surgery or newer methods that place heated medicine directly into the abdomen. These newer treatments can help some people feel better and live longer. Sometimes they may even lead to a cure.

Some people may notice symptoms of peritoneal carcinomatosis early, while others may not feel anything until the disease has gotten worse. Symptoms often become more noticeable when cancer cells grow and start affecting nearby organs, such as the intestines, bladder and stomach.

The most common symptoms include:

• Abdominal swelling or bloating. This is the most common symptom. Swelling is caused by fluid buildup, called ascites, in the belly. Someone may feel that they are gaining weight in the belly despite exercise. Women in menopause may appear as if they are pregnant.
• Abdominal pain or discomfort. This is often described as vague cramping or pressurelike pain.
• Loss of appetite. Someone may feel full quickly, even after small meals.
• Losing weight without trying. This weight loss is not related to changes in diet or activity.
• Fatigue. Someone may feel very tired, even after resting.
• Nausea and vomiting. These are often linked to bowel issues caused by tumor pressure.
• Bowel changes. These can include constipation or diarrhea and, sometimes, a blockage that prevents food or gas from passing.
• Bleeding. Peritoneal carcinomatosis may cause rectal or vaginal bleeding.

Other possible symptoms include:

• Urinary symptoms. If cancer spreads near the bladder or ureters, it may cause changes in urination or block urine flow. The ureters are thin tubes that carry urine from each kidney to the bladder.
• Shortness of breath. This is usually due to pressure from fluid buildup pushing on the lungs.

Peritoneal carcinomatosis develops when cancer cells break off from other organs. The cells then travel into the abdominal cavity and attach to the lining of the belly, called the peritoneum. The peritoneum has a large surface area with a rich blood supply. This allows cancer cells to grow quickly.

The most common cancers that can lead to peritoneal carcinomatosis include:

• Ovarian cancer.
• Colon or rectal cancer.
• Stomach cancer.
• Pancreatic cancer.
• Appendix cancer.
• Less commonly, breast, lung, neuroendocrine or skin cancer or gastrointestinal stromal tumors.

Cancer that starts in the peritoneum is called primary peritoneal cancer. This is much rarer than peritoneal carcinomatosis that has spread from other organs, which is considered a secondary or metastatic cancer. The most common primary peritoneal cancer is peritoneal mesothelioma.

Most of the time, peritoneal carcinomatosis happens when cancer spreads to the peritoneum from another part of the body. Some traits of the cancer or the person can make the cancer more likely to spread to the peritoneum.

• Advanced or larger cancers. Cancers that grow through the outermost layers of the organs or spread to lymph nodes are more likely to reach the peritoneum.
• Certain types of cancer cells. Some cancer cells, including mucinous and signet ring cancer cells, are strongly linked to peritoneal carcinomatosis. These types of cancers can be fast growing and aggressive and are more likely to spread throughout the abdomen rather than stay in one spot. That raises the risk that they will cause peritoneal carcinomatosis.
• Lymph node involvement. When cancer has already spread to nearby lymph nodes, the risk of peritoneal carcinomatosis is higher.
• Surgery to remove primary cancer. Having surgery to remove primary cancer in nearby organs increases the risk of cancer cells spreading during the procedure. If the cancerous tissue is accidentally cut or leaks during surgery, cancer cells can spill into the abdominal cavity. These cells can implant on the peritoneum and grow into new cancers.
• Cancer location. Cancers on the right side of the colon are more likely to spread to the peritoneum than are cancers on the left side of the colon.

Peritoneal carcinomatosis can lead to several serious complications as the cancer spreads and affects organs within the abdominal cavity:

• Fluid buildup in the belly. Cancer cells in the peritoneum often cause fluid to build up in the belly, a condition called ascites. This leads to bloating, discomfort, shortness of breath and, sometimes, infection. Fluid may need to be drained often, sometimes through catheters that you or your caregiver must manage at home.
• Bowel blockage. As cancer spreads across the peritoneum, it can press on or wrap around the intestines. This can lead to a bowel blockage, called obstruction. This can cause severe pain and vomiting and make it difficult to pass stool or eat. Obstructions may require emergency surgeries.
• Urinary blockage. In peritoneal carcinomatosis, cancer can press on or grow around the thin tubes called ureters that carry urine from each kidney to the bladder. This can block the flow of urine.
• Trouble absorbing nutrients. When the intestines aren't working well, the body can't take in enough nutrients from food. Over time, this can make a person weak and raise the risk of conditions such as infections or poor nutrition.

Peritoneal carcinomatosis often spreads across the abdominal lining without forming distinct masses. Because of this, doctors usually need to combine imaging, fluid tests, and sometimes surgery, to confirm a diagnosis.

Tests

• Imaging tests. Imaging tests such as CT, MRI and PET scans are typically the first step in looking for suspected peritoneal carcinomatosis. These scans help identify visible tumor spread, fluid buildup or organ involvement. However, imaging is often not sensitive enough to detect smaller cancers or early peritoneal disease. Therefore, a negative scan does not rule out peritoneal carcinomatosis.
• Peritoneal washing cytology. In this test, fluid from the abdominal cavity is surgically collected during a minor procedure. It's then examined under a microscope. Healthcare professionals use peritoneal washing cytology to check for cancer cells floating in the peritoneal fluid. Even when no visible cancer is present, a positive cytology result is a strong sign that peritoneal spread has happened.
• Staging laparoscopy. Staging laparoscopy is a safe, minimally invasive surgical procedure used to look directly inside the abdominal cavity using a small camera. It allows healthcare professionals to inspect the peritoneum, find hidden tumors, and take tissue or fluid samples. This test is especially valuable for finding peritoneal metastases that are too small to be seen with imaging.
• Tumor marker tests. Tumor marker tests use a sample of blood to look for chemicals made by cancer cells.
• Circulating tumor DNA (ctDNA). This is a newer blood test that looks for small pieces of DNA from cancer cells in the blood. It can help find peritoneal cancer that doesn't show up on scans. However, the role of ctDNA in diagnosis is still uncertain.

Treatment for peritoneal carcinomatosis often requires a combination of therapies. The exact plan depends on where the cancer started, how far it has spread and your overall health. Your healthcare team also considers your treatment goals, such as extending life, symptom relief or both.

Systemic chemotherapy

The most common treatment for peritoneal carcinomatosis is systemic chemotherapy. This is medicine given through the blood to reach the whole body. Chemotherapy uses strong medicines to kill cancer cells, help shrink tumors, and relieve symptoms such as pain or bloating. Chemotherapy also may allow for surgery later.

However, systemic chemotherapy doesn't reach the peritoneum as well as it does other parts of the body, which can limit how well it works for peritoneal carcinomatosis.

Immunotherapy

Immunotherapy is another type of systemic treatment that may be offered for certain cancers.

Cytoreductive surgery

Cytoreductive surgery (CRS) removes all visible cancer from the peritoneum and other organs in the abdomen. Also known as debulking surgery, CRS is a major operation and should only be done in centers with experience. It's best for people who are healthy enough for surgery and whose cancer can be mostly or completely removed.

Hyperthermic intraperitoneal chemotherapy

Hyperthermic intraperitoneal chemotherapy (HIPEC) is typically combined with CRS. After the cancer is removed during surgery, the abdominal cavity is bathed with heated chemotherapy to target any remaining microscopic cancer cells.

This combined approach, often referred to as CRS-HIPEC or HIPEC surgery, allows for higher medicine concentrations to reach cancer in the peritoneum. This can lessen the typical side effects people often have with systemic chemotherapy due to less absorption in the bloodstream.

Research has shown that HIPEC can prevent cancer from returning for certain people whose cancer has spread to the abdominal cavity. Therefore, HIPEC may prolong survival.

Pressurized intraperitoneal aerosolized chemotherapy

Pressurized intraperitoneal aerosolized chemotherapy (PIPAC) is a newer method to treat peritoneal carcinomatosis. During PIPAC, a special aerosolized mist of chemotherapy medicine is put directly into the belly during a minimally invasive procedure. The medicine is given as a fine aerosol under pressure, which helps it spread evenly throughout the abdomen. PIPAC is typically done when surgery isn't possible or when surgery would be too risky or not helpful.

Palliative care

When peritoneal carcinomatosis can't be cured or treated with chemotherapy or surgery, the focus may turn to comfort and quality of life. Palliative care is a special type of healthcare that focuses on relieving pain and other symptoms, such as digestive issues, malnutrition and fluid buildup, called ascites. Treatments may include fluid drainage, pain relief medicines and nutritional support.

Palliative care involves a team of healthcare professionals. The team can include doctors, nurses and other specially trained health professionals. The goal is to improve the quality of life for people with serious illnesses and their families.

Prognosis

Peritoneal carcinomatosis is a serious and often late-stage condition. Depending on how aggressive the cancer is, people with peritoneal carcinomatosis from more advanced cancers may live only 4 to 6 months on average when treated with systemic chemotherapy alone.

However, some people may live longer if they are healthy enough to have CRS-HIPEC. In some studies, CRS-HIPEC extended survival by more than three years. For people who can't have surgery, newer treatments such as PIPAC also may help them live longer.

It can be hard to cope with a cancer diagnosis, especially if it's a cancer recurrence or metastasis. In time, people learn to cope in their own ways. Until you find what works for you, you might try to:

• Learn enough about your cancer to make treatment decisions. Ask your healthcare team about your treatment options and their side effects. The more you know, the more you'll be able to take part in decisions about your care. Ask your healthcare team to recommend other sources of information, such as websites you can trust.
• Keep friends and family close. Keeping people you care about close to you can help you deal with cancer. Friends and family can help you take care of things if you're in the hospital. And they can offer you support when you feel like you have too much to handle.

• Find someone to talk with. Find a good listener with whom you can talk about your hopes and fears. This may be a friend or family member. Talking with a counselor, medical social worker, clergy member or cancer support group also might be helpful.

  Ask your healthcare team about support groups in your area or contact a cancer organization, such as the National Cancer Institute or the American Cancer Society.

If you have peritoneal carcinomatosis, you'll likely be sent to specialists who treat advanced disease. You might meet with:

• A doctor who uses medicines to treat cancer, called an oncologist.
• A doctor who removes cancer using surgery, called a surgeon or surgical oncologist.

Here's some information to help you get ready for your appointment.

What you can do

Ask a family member or friend to go to your appointment with you. This person can help you remember the information you're told.

Make a list of:

• Your symptoms and when they began.
• Key medical information, including other conditions you have and your family medical history.
• All medicines, vitamins and supplements you take, including doses.
• Questions to ask your healthcare team.

Some basic questions to ask include:

• How serious is my condition?
• Can you explain the lab report of my cancer to me?
• Can I have a copy of my lab report?
• Will I need more tests?
• What are the treatment options for my cancer?
• What is the chance that my cancer can be cured?
• What are the potential side effects of each treatment?
• How will each treatment affect my daily life?
• How much time can I take to decide about treatment?
• Are clinical trials available for me?

What to expect from your doctor

Be prepared to answer some basic questions about your symptoms, such as:

• What are your symptoms?
• Is there a family history of cancer, especially at a young age? And what types of cancer?
• Have you or any relatives been tested for Lynch syndrome or other hereditary cancer conditions?
• Do you have any other health conditions, such as diabetes, heart disease or kidney disease?