Peritoneal mesothelioma is a type of malignant cancer that is caused by ingested asbestos fibers. It develops in the peritoneum, the thin layer of tissue lining the abdomen. Symptoms of peritoneal mesothelioma include abdominal pain, nausea and swelling in the abdomen (ascites).
What Is Peritoneal Mesothelioma?
Peritoneal mesothelioma is a rare asbestos-related cancer of the abdomen. This cancer forms on the abdominal lining, which is known as the peritoneum. Doctors diagnose about 600 cases of peritoneal mesothelioma in the United States each year.
Peritoneal mesothelioma symptoms are usually broad and similar to those of many other illnesses. General practitioners often misdiagnose peritoneal mesothelioma as a less severe abdominal condition.
Confirming an accurate diagnosis typically requires a history of asbestos exposure and a tissue sample known as a biopsy.QUICK FACTS ABOUT PERITONEAL MESOTHELIOMA
- The peritoneum lines the abdominal cavity and carries blood vessels and nerves to abdominal organs while also providing structural support.
- A rarer form of this cancer develops in the omentum, a layer of the abdominal membrane covering the stomach and other organs.
- Early symptoms include abdominal distention and fluid buildup known as ascites.
- Peritoneal mesothelioma accounts for less than 20% of all mesothelioma cases.
- The average life expectancy of peritoneal mesothelioma patients is 12 months.
- Surgery with heated chemotherapy is the most effective treatment, and some patients survive for more than five years.
- Clinical trials are available for peritoneal mesothelioma and include new treatments such as immunotherapy.
- The primary cause of peritoneal mesothelioma is swallowing airborne asbestos fibers or drinking contaminated water. The digested fibers become trapped in the peritoneum.
What Are the Symptoms of Peritoneal Mesothelioma Cancer?
Early symptoms of peritoneal mesothelioma include bloating, pain or tenderness around the abdomen, and digestion issues such as constipation or diarrhea.
These symptoms tend to mimic many other abdominal disorders. An accurate diagnosis often requires a mesothelioma specialist.
Anyone with a history of asbestos exposure should monitor their health and see their doctor for any new or worsening symptoms.
PERITONEAL MESOTHELIOMA SYMPTOMS INCLUDE:
- Abdominal pain
- Abdominal swelling (ascites)
- Night sweats
- Nausea
- Fever
- Unexplained weight loss
- Fatigue
- Diarrhea
- Constipation
- Loss of appetite
What Causes Peritoneal Mesothelioma?
Ingesting asbestos fibers causes malignant peritoneal mesothelioma. Exposure can occur from swallowing airborne fibers or swallowing water contaminated with asbestos. Current research suggests that asbestos fibers travel from the digestive tract and remain trapped in the abdomen, causing cancer after years of inflammation.
THE STEPS OF PERITONEAL MESOTHELIOMA DEVELOPMENT INCLUDE:
- Swallowed asbestos fibers pass through the stomach and digestive system.
- Ingested asbestos fibers reach the lymphatic system and travel to the peritoneum.
- Once fibers are in the peritoneum, they irritate cells and damage DNA over many 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.
Research on peritoneal mesothelioma is still ongoing. Other sources of this disease may include abdominal radiation and fibrous minerals besides asbestos, such as erionite.
How Is Peritoneal Mesothelioma Diagnosed?
Abdominal mesothelioma is diagnosed with imaging scans, blood tests and biopsies.
- 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.
Patients will also receive a thorough examination of their medical history, occupational history and overall physical condition.
While every test serves a contributing purpose to the diagnostic process, the only way to confirm a peritoneal mesothelioma diagnosis is with a biopsy.
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.
Diagnosing Cell Types of Peritoneal Mesothelioma
The pathology report contains information about which cellular subtype of peritoneal mesothelioma you have.
Common Cell Types
- Epithelioid cells are the most common, making up 75% of cases.
- The biphasic type, which is a combination of epithelioid and sarcomatoid cells, is the second most common. It comprises about 25% of cases.
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 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
- Multicystic mesothelioma
- Desmoplastic mesothelioma
- Lymphohistiocytoid mesothelioma
- Pure sarcomatoid mesothelioma
Additionally, omental mesothelioma is a rare variant that forms in the omentum, a part of the peritoneum surrounding the stomach and other abdominal organs.
Peritoneal Mesothelioma Staging
There is no official staging system for peritoneal mesothelioma. Instead, peritoneal mesothelioma experts spent decades adapting other staging systems for their use.
Historically, the TNM staging system used in other cancers has not been a good fit for peritoneal mesothelioma due to the diffuse pattern of growth. However, a research report in 2026 suggested that oncologists could adapt the TNM system for peritoneal mesothelioma into three stages.
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 peritoneal mesothelioma. Many doctors consider stage 4 to involve extensive tumors that have spread to distant sites throughout the body.
Peritoneal Mesothelioma Treatment Options
The most effective peritoneal mesothelioma treatment option is surgery with heated chemotherapy, also known as hyperthermic intraperitoneal chemotherapy, or HIPEC. However, chemotherapy alone is the most commonly used treatment for peritoneal mesothelioma.
More than 60% of patients are ineligible for surgery with heated chemotherapy due to the procedure’s intensity. Cytoreductive surgery can take several hours and may involve removing large portions of the intestines or whole organs.