Last modified: October 15, 2021
What Is Peritoneal Mesothelioma?
Peritoneal mesothelioma is a rare asbestos-related cancer that forms on the abdominal lining, known as the peritoneum. An even rarer form of this cancer develops in a layer of the abdominal membrane, the omentum, that covers the stomach and other organs.
- Early symptoms include abdominal swelling and fluid buildup (known as ascites).
- Peritoneal mesothelioma accounts for less than 20% of all mesothelioma cases.
- Surgery with heated chemotherapy is the most effective treatment, helping some patients survive for more than five years.
The primary cause of peritoneal mesothelioma is swallowing airborne asbestos fibers or drinking contaminated water. The digested fibers become trapped in the peritoneum.
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 ConwayPeritoneal mesothelioma specialist
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.
Peritoneal mesothelioma symptoms include:
- Abdominal pain
- Abdominal swelling (ascites)
- Night sweats
- Unexplained weight loss
- Loss of appetite
These symptoms tend to mimic many other abdominal disorders. An accurate diagnosis often requires a mesothelioma specialist and a biopsy sample.
Anyone with a history of asbestos exposure should monitor their health and see their doctor for new or worsening symptoms.
What Causes Peritoneal Mesothelioma?
The main cause of malignant peritoneal mesothelioma is ingesting asbestos fibers. Current research suggests that asbestos fibers travel from the digestive tract and remain trapped in 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.
- Swallowed asbestos fibers pass through the stomach and digestive system.
- Ingested 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.
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?
Imaging scans, blood tests and biopsies are used to make an abdominal mesothelioma diagnosis.
- 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.
- Biphasic Cells: Second-most common type, making up 25% of cases. 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 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 with 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 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.
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.
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 LittlePeritoneal mesothelioma survivor
Stages of Peritoneal Mesothelioma
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 its diffuse growth pattern. However, a research report in 2020 suggested that oncologists 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 Cancer Index
The Peritoneal Cancer Index is a diagnostic tool that 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 surgery with heated chemotherapy, known as hyperthermic intraperitoneal chemotherapy, or HIPEC. However, chemotherapy alone is the treatment most used for peritoneal mesothelioma.
More than 60% of patients are ineligible for surgery with heated chemotherapy because of the procedure’s intensity. Cytoreductive surgery can take several hours and may involve removing large portions of the intestines or whole organs.
Patients who don’t qualify for surgery with heated chemotherapy can receive systemic chemotherapy alone. 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 extended his life by four years, allowing him to find joy in the little things and see his youngest child graduate high school.
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 MadarisDiagnosed with peritoneal mesothelioma in 2013
Cytoreductive Surgery with Heated Chemotherapy
Cytoreductive surgery, also known as a peritonectomy, attempts to remove as much cancer as possible. Then, 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.
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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. Peritoneal mesothelioma life expectancy is approximately 12 months for patients who receive chemotherapy alone. The median survival of untreated peritoneal mesothelioma patients is six months.
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.
According to a 2020 study published in the American Journal of Surgical Pathology, women with 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.
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 still rides to work on her scooter and refuses to let mesothelioma get in the way of the life she and her husband built. They don’t know how many wedding anniversaries they will have, but they celebrate their time together. “It’s kind of cool now to hear people say, ‘You don’t look or act sick,’” Alexis said.
When averaging short- and long-term survival, women live approximately 13 months on average, and men live roughly six months.
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)
- 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 a repeat surgery with heated chemotherapy if a 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.
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.
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 patients and families with one another and offers professional guidance from facilitators. Dana Nolan, MS, LMHC, is a licensed counselor and serves as our 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.
- Is peritoneal mesothelioma curable?
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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