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Last Modified September 20, 2022
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What Is Malignant Peritoneal Mesothelioma?

Malignant peritoneal mesothelioma is a rare and aggressive cancer that forms in the abdomen. It’s also known as abdominal mesothelioma or mesothelioma of the stomach.

The primary proven cause of malignant peritoneal mesothelioma is asbestos exposure. Asbestos fibers are inhaled or ingested and become lodged in the abdomen.

About 300 to 500 peritoneal mesothelioma cases are diagnosed each year in the U.S. The incidence is distributed equally among women and men. This contrasts with pleural mesothelioma, which develops in the lungs and is far more common in men.

An even rarer form of peritoneal mesothelioma cancer develops in a layer of the abdominal membrane, the omentum, that covers the stomach and other organs.

W. Charles Conway
“The first thing I like to tell [peritoneal mesothelioma patients] is that they certainly do have options. With good treatment that we use now, that median survival could actually be several years.”
Dr. W. Charles Conway
Peritoneal mesothelioma specialist

What Are the Symptoms of Peritoneal Mesothelioma Cancer?

Presenting symptoms of peritoneal mesothelioma include bloating, pain or tenderness around the abdomen, and digestion issues such as constipation or diarrhea. Symptoms of peritoneal mesothelioma do not develop in many patients until the cancer reaches an advanced stage.

Peritoneal Mesothelioma Symptoms Include:

  • Abdominal pain
  • Abdominal swelling (ascites)
  • Night sweats
  • Nausea and vomiting
  • Fever
  • Unexplained weight loss
  • Fatigue
  • Diarrhea
  • Constipation
  • Loss of appetite
  • Bowel or urinary problems

These symptoms tend to mimic many other abdominal disorders. An accurate diagnosis often requires a mesothelioma specialist and a biopsy sample. 

Anyone who was exposed to asbestos should discuss their history with their doctor. Mesothelioma screenings, such as regular imaging tests, may be recommended. Your doctor can monitor any new or worsening symptoms.

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What Causes Peritoneal Mesothelioma?

The main cause of malignant peritoneal mesothelioma is exposure to asbestos fibers. Current research suggests that asbestos fibers may travel through the bloodstream to reach the abdomen, causing cancer after years of inflammation.

Process of Peritoneal Mesothelioma Development

Like other asbestos-related diseases, peritoneal mesothelioma develops over a long period of time. The trapped asbestos fibers cause inflammation and irritation, damaging and degrading DNA. 

Damaged DNA can lead to abnormal and unregulated cell growth. These errors cause tumors to form, and the tumors can grow uncontrollably and spread to other areas of the body.

How Peritoneal Mesothelioma Develops
  • Inhaled or swallowed asbestos fibers pass through the bloodstream and digestive system.
  • Asbestos fibers reach the lymphatic system and travel to the peritoneum.
  • Fibers become stuck in the peritoneum, irritating cells and damaging DNA for years.
  • The irritated cells become inflamed, form scar tissue and thicken the peritoneal lining.
  • Years of inflammation and scar tissue formation cause excess abdominal fluid buildup.
  • After prolonged damage, malignant tumors begin to form on the diseased peritoneum.
  • As tumors grow, they put pressure on vital organs and can spread to form new tumors.
peritoneal mesothelioma development.
How peritoneal mesothelioma develops

Research on malignant peritoneal mesothelioma is still ongoing. This disease is rare and connected to toxic exposure to industrial pollutants, including asbestos. Other potential causes of the disease may include exposure to abdominal radiation and fibrous minerals besides asbestos, such as erionite.

How Is Peritoneal Mesothelioma Diagnosed?

While every diagnostic test serves a contributing purpose to the diagnostic process, the only way to confirm a malignant peritoneal mesothelioma diagnosis is with a biopsy. In addition to a biopsy, imaging scans and blood tests are typically used in the abdominal mesothelioma diagnosis process.

  • Imaging scans show the size and location of tumors.
  • Blood tests reveal certain biomarkers associated with cancer.
  • Biopsies show what kind of cancerous cells are present.

Biopsies are samples of tumor tissue that doctors examine under a microscope in a lab. Medical professionals, called pathologists, perform tests on the biopsy sample to reveal the kinds of cancerous cells within the tumors. They then summarize the results in a pathology report.

Patients will also receive a thorough examination of their medical history, occupational history and overall physical condition.

Diagnosing Peritoneal Mesothelioma Cell Types

The pathology report contains information about which cellular subtype of peritoneal mesothelioma you have. Diagnosing the cell type is important because it helps doctors determine which therapies may work best for you.

Common Cell Types

  • Epithelioid cells: This is the most common, making up 75% of cases.
  • Biphasic Cells: Biphasic is the second-most common type, making up 25% of cases. It is a mix of epithelioid and sarcomatoid cells.

Epithelioid peritoneal mesothelioma can grow in four different patterns: Papillary, tubular, diffuse and deciduous. Papillary is the most common and often appears alongside the others.

Pure sarcomatoid tumors are uncommon in malignant peritoneal mesothelioma. Specialists have only diagnosed about 30 cases of this variant since 2006. Sarcomatoid cells usually occur alongside epithelioid cells to form the biphasic subtype.

Rare Cell Types

  • Well-Differentiated Papillary Mesothelioma: This variant is uncommon, with less potential for malignancy, and typically presents in younger women.
  • Multicystic Mesothelioma: This subtype often recurs after surgery and does not have a definitive link to asbestos exposure.
  • Desmoplastic Mesothelioma: This tumor type can present as nodules or a mass-like peritoneal thickening, ascites or lymph node disease.
  • Lymphohistiocytoid Mesothelioma: A dense lymphatic infiltrate characterizes this variant.
  • Pure Sarcomatoid Mesothelioma: The rarest and most lethal form of peritoneal mesothelioma, this subtype is associated with aggressive metastasis.

Additionally, omental mesothelioma is a rare variant that occurs in the omentum, a part of the peritoneum surrounding the stomach and other abdominal organs. The omentum is a layer of fatty tissue that plays a role in immune function and metabolism.

Misdiagnosing Peritoneal Mesothelioma

Because this cancer is rare, doctors lacking experience with the disease often misdiagnose abdominal mesothelioma patients with more common illnesses that share similar symptoms. Peritoneal mesothelioma misdiagnosis can delay proper treatment.

If you have a history of asbestos exposure, the best way to ensure an accurate diagnosis is to schedule an appointment with a mesothelioma specialist. Doctors who specialize in peritoneal mesothelioma have the knowledge and tools needed to make a precise diagnosis.

Tamron Little, mesothelioma survivor and an Asbestos.com expert contributor
“Getting an accurate diagnosis was not easy. A fibroid tumor was what they said I had and that it would go away on its own. I asked the doctors, and they all told me, ‘You will be fine.’ It took a specialist to get the breakthrough I needed.”
Tamron Little
Peritoneal mesothelioma survivor
Cancer Misdiagnosis Experience

Watch: Peritoneal mesothelioma survivor Tamron Little talks to The Mesothelioma Center about her initial misdiagnosis and the importance of finding a specialist.

Stages of Peritoneal Mesothelioma

While there is no official staging system for peritoneal mesothelioma, a research report in 2020 suggested that oncologists adapt the TNM system, widely used for pleural mesothelioma, into three stages for peritoneal.

Illustration of staged progression of peritoneal mesothelioma. Early-stage tumors are localized in one area of the peritoneal lining. Mid-stage peritoneal mesothelioma may be more extensive and involve deeper tissues or lymph nodes. Late-stage cancer has spread to distant structures in the abdomen.
progression of peritoneal mesothelioma.

3 Stages of Peritoneal Mesothelioma

  • Stage 1: Cancerous tissue is minimal, tumors are only within the abdominal lining and lymph nodes are free of cancer.
  • Stage 2: Cancerous tissue is moderate and tumors have not spread outside the lining or into lymph nodes.
  • Stage 3: Cancerous tissue is more extensive and tumors may have spread outside the peritoneal lining or into lymph nodes.

There is no precise fourth stage in the adapted TNM system for malignant peritoneal mesothelioma. Many doctors consider stage 4 to involve extensive tumors that have spread to distant sites throughout the body.

Peritoneal Cancer Index

The Peritoneal Cancer Index is a diagnostic tool doctors use to assess tumor location and spread in the abdomen. It helps them determine the approximate mesothelioma stage and appropriate treatments.

This index divides the abdomen into 13 parts. Doctors assign a number (one to three) to each area based upon the most sizable tumor in that area. The Peritoneal Cancer Index score is the sum of the individual scores from the 13 regions. A patient’s maximum score is 39 (13 times three).

Lower index scores mean the patient may qualify for surgery. Index scores above 20 indicate cancer has spread too far and the patient likely won’t respond well to surgery.

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Peritoneal Mesothelioma Treatment Options

The most effective peritoneal mesothelioma treatment option is cytoreductive surgery with heated chemotherapy, known as hyperthermic intraperitoneal chemotherapy, or HIPEC.

More than 60% of patients are ineligible for surgery with heated chemotherapy, however, because of the procedure’s intensity. Because cytoreductive surgery can take several hours and may involve removing large portions of the intestines or whole organs, chemotherapy alone is the most used treatment.


Heated Intraperitoneal chemotherapy (HIPEC) treatment for peritoneal mesothelioma
HIPEC treatment process

Patients who don’t qualify for surgery with heated chemotherapy can receive systemic chemotherapy alone. Some patients receive only intraperitoneal chemotherapy. 

Chemotherapy drugs can shrink peritoneal mesothelioma tumors and slow the growth and spread of cancer. Chemotherapy drugs that are effective against peritoneal mesothelioma include pemetrexed, cisplatin, carboplatin and gemcitabine.

U.S. Navy pilot and peritoneal mesothelioma survivor Jim Madaris decided to seek out the HIPEC procedure after his diagnosis in 2013. The surgery took 14 hours and removed his gallbladder, spleen and parts of his intestine. Madaris’ life was extended by four years, allowing him to find joy in the little things and see his youngest child graduate high school.

Mesothelioma survivor Jim Madaris
“I’m fortunate. I’ve lasted four times longer than my first doctor expected. Even if something happens tomorrow, we’re still calling it a victory.”
Jim Madaris
Diagnosed with peritoneal mesothelioma
Cytoreductive surgery for peritoneal mesothelioma
Cytoreductive surgery targets multiple sites in the abdomen.

Cytoreductive Surgery with Heated Chemotherapy

Cytoreductive surgery, also known as a peritonectomy, attempts to remove as much cancer as possible. Heated chemotherapy is applied locally to the abdomen before the surgery ends. Doctors only perform this procedure on a case-by-case basis. A 2019 study reported that more than 65% of the patients who underwent this procedure lived five years or longer.

Palliative Treatment Options

In addition to anti-cancer treatments, many peritoneal patients receive palliative care to control symptoms and improve quality of life. For example, a paracentesis procedure may be recommended to certain peritoneal patients to drain excess fluid from the abdomen.

A palliative care specialist prescribes medications to control pain and side effects. They may refer patients to physical or occupational therapy or recommend complementary therapies.

Top Peritoneal Doctors

Paul H. Sugarbaker
Surgical Oncologist

Dr. Paul Sugarbaker is the country’s leading expert on peritoneal mesothelioma. He developed the widely renowned cytoreductive surgery and heated chemotherapy technique that changed the landscape of peritoneal cancer treatment. Many people with peritoneal mesothelioma are alive today because of Sugarbaker’s innovations.

W. Charles Conway
Surgical Oncologist

Dr. W. Charles Conway is an expert in peritoneal mesothelioma and the Director of Surgical Oncology at Ridley-Tree Cancer Center in Santa Barbara, California. He specializes in minimally invasive robotic surgery and heated chemotherapy for peritoneal mesothelioma.

J.F. Pingpank Jr.
Surgical Oncologist

Dr. J.F. Pingpank Jr. is a peritoneal mesothelioma expert who advocates for regional therapy. The approach applies treatment locally around the cancer to limit damage to the rest of the body. Pingpank specializes in cytoreductive surgery and heated chemotherapy.

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Peritoneal Mesothelioma Life Expectancy and Prognosis

The prognosis for peritoneal mesothelioma is generally poor for patients who don’t qualify for surgery. Those who qualify for multimodal treatment, however, may improve their prognosis by several years.

Peritoneal mesothelioma life expectancy is approximately 12 months for patients who receive chemotherapy alone. The median survival of peritoneal mesothelioma patients who do not undergo any treatment is six months.

Diagram showing average peritoneal mesothelioma life expectancy
25% of peritoneal mesothelioma patients survive three years after diagnosis.

However, the prognosis for surgical candidates is significantly better. Surgery and heated chemotherapy can improve peritoneal survival by several years. 

About half of peritoneal patients who undergo a combination of cytoreductive surgery with heated chemotherapy have a life expectancy of more than five years.

Survivor Insight

Alexis was diagnosed with peritoneal mesothelioma in 2007, had major surgery that removed part of her diaphragm, yet kept her wedding plans in place. She refuses to let mesothelioma get in the way of the life she and her husband have built. “It’s kind of cool now to hear people say, ‘You don’t look or act sick,’” Alexis said.

Alexis K.
Peritoneal mesothelioma survivor

According to a 2020 study published in the American Journal of Surgical Pathology, women with malignant peritoneal mesothelioma tend to live longer than men. In the study, 77.8% of women treated with cytoreductive surgery and heated chemotherapy at MD Anderson Cancer Center in Houston survived longer than five years. 

When averaging short- and long-term survival, women live approximately 13 months on average, and men live roughly six months.

When averaging short- and long-term survival, women live approximately 13 months on average, and men live roughly six months.

Factors Affecting Prognosis

Patients with tumors containing epithelial cells have a longer life expectancy than patients with sarcomatoid or biphasic cells. Epithelial cells tend to respond better to treatments such as chemotherapy.

  • Stage at diagnosis
  • Cell type
  • Tumor grade (how fast it grows)
  • Gender
  • Genetic mutations
  • Treatments selected

The tumor’s grade also impacts prognosis. Tumor grade indicates how quickly tumors are likely to grow and spread, based upon how abnormal the cells appear.

Chemotherapy Survival Rates

Systemic (whole-body) chemotherapy combined with cisplatin and pemetrexed has the following benefits:

  • A response rate of about 30%
  • Average progression-free survival around 11.5 months
  • Median survival around 13 months

Chemotherapy delivered directly to the peritoneum without surgery has a higher response rate of 47%. When combined with heated chemotherapy given during surgery, the response rate is 84.6%

Is There a Cure for Peritoneal Mesothelioma?

There is no cure for peritoneal mesothelioma or any other type of mesothelioma. However, peritoneal patients eligible for surgery and HIPEC typically live longer than five years.

Some patients may be eligible for repeat surgery with heated chemotherapy if a cancerous mesothelioma recurrence happens.

In 2017, Dr. Paul Sugarbaker reported improved survival among patients who received early post-operative chemotherapy and long-term chemotherapy after cytoreductive surgery with heated chemotherapy.

Of the 29 patients who had surgery with HIPEC, post-operative chemotherapy and long-term chemotherapy, 75% lived longer than five years. No patients in the study received intravenous or systemic chemotherapy.

Doctor reviewing x-ray
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Survivor Insight

They tell you how HIPEC affects you physically, but no one tells you how it affects you mentally. To be honest, it was a bit rough, but I’m glad I got through it.

Tamron Little
Peritoneal Mesothelioma Survivor

Feelings of depression or loneliness are common among peritoneal mesothelioma patients. Support services such as counselors and support groups are available. Talking to a counselor or joining a support group can help improve quality of life.

The Mesothelioma Center, for example, hosts an online support group that connects mesothelioma patients and families with one another and offers professional guidance from facilitators. Dana Nolan, MS, LMHC, is a licensed counselor and serves as the moderator. Patient advocate and registered nurse Karen Selby is also available to answer medical questions.

Common Questions About Peritoneal Mesothelioma

What are the symptoms of peritoneal mesothelioma?

The symptoms of peritoneal mesothelioma include abdominal pain, abdominal swelling or distension, diarrhea or constipation, weight loss and fatigue. Other symptoms may develop as the disease progresses, such as fever and night sweats.

How fast does peritoneal mesothelioma spread?

Peritoneal mesothelioma spreads fairly quickly. Exact rates of spread vary individually and are affected by the cell type of the tumors. Patients who do not undergo treatment have a median survival of six months. This means peritoneal mesothelioma spreads significantly within half a year without treatment.

Is peritoneal mesothelioma curable?

Malignant peritoneal mesothelioma is incurable at all four stages. Clinical trials are searching for a cure by testing new treatments, including immunotherapy and multimodal therapy.

How long do peritoneal mesothelioma patients live?

Peritoneal mesothelioma patients have a life expectancy of about one year. However, survival is significantly better for patients who qualify for surgery with heated chemotherapy. Half of the patients who qualify for this procedure live at least five years.

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