What Is Peritoneal Mesothelioma?
Peritoneal mesothelioma is a cancer of the peritoneum.[1] It is also known as peritoneal cancer.
The peritoneum is a thin membrane that creates the lining of the abdominal cavity, arising from mesothelial cells. It consists of two thin layers called the visceral peritoneum and the parietal peritoneum.[2]
Facts About Peritoneal Mesothelioma
Because this cancer is so rare, most people don’t know much about it. Here are some quick facts about peritoneal mesothelioma:[1]
- All types of mesothelioma are aggressive and spread rapidly.
- Known asbestos exopsure occurs in only about half of all cases of peritoneal mesothelioma.
- Women, especially those without past asbestos exposure, account for most cases of multicystic and well-differentiated peritoneal mesothelioma. These types have long survival times.
- Mesothelioma is rare, accounting for about 3,000 cases of cancer per year. Of those, only 200 to 400 are peritoneal mesothelioma.
- The highest number of diagnoses occurs in people between the ages of 50 and 69.
- Between 2% and 5% of peritoneal mesothelioma cases occur in people aged 20 or younger.
- Survival time is often longer for peritoneal mesothelioma than for pleural mesothelioma.
What Causes This Type of Mesothelioma?
The main cause of any type of mesothelioma is asbestos exposure.[1] The longer and more frequent the exposure, the greater the risk of developing mesothelioma.
Experts believe other risk factors, like genetics and family history, also play a role because not everyone exposed to asbestos develops cancer.[3] Also, some patients with peritoneal mesothelioma have no known history of asbestos exposure.
Prolonged asbestos exposure is most often associated with pleural mesothelioma because exposure is usually through inhalation of the fibers, but it can also trigger the peritoneal form in the abdomen.
There are two possible ways that asbestos fibers may travel to the abdominal cavity and cause peritoneal cancer:[3][4]
- Asbestos fibers may also be ingested and may be present in the sputum. Over time, these fibers reach the peritoneal surface by penetrating the wall of the intestine. This process can ultimately lead to the development of cancerous cells.
- Fibers that have been inhaled may also migrate through the lymphatic system and end up in the abdomen, where they cause damage.
How Peritoneal Mesothelioma Develops
Whether they get there through inhalation or ingestion, asbestos fibers in the abdomen become embedded in the peritoneum cells. There, they trigger inflammation and damage.
Cellular damage can lead to cancerous cells that grow and divide out of control. These cells then develop into tumors that may spread further through the peritoneum to other tissues and organs.
What if I Was Never Exposed to Asbestos?
Peritoneal differs from the pleural form of mesothelioma in that more patients report no exposure to asbestos. Asbestos causes cancer typically by inhalation of the fibers, which is why pleural mesothelioma is more common.
Approximately half of all people diagnosed with the peritoneal form have no known past asbestos exposure. There may be several explanations for this:[1]
- They did encounter asbestos in the past, but didn’t realize it.
- They experienced asbestos exposure second-hand, for instance, by living with someone who works around asbestos and unintentionally brings fibers home on clothing or in hair.
- There may be other causes of mesothelioma, such as genetics, radiation exposure, or exposure to a virus known as SV40.
If you have symptoms of peritoneal mesothelioma but no known exposure, doctors will first eliminate other, more likely causes.
Why Are Women More Likely to Get Peritoneal Mesothelioma?
The majority of cases of both pleural and peritoneal mesothelioma are in men. However, more women receive diagnoses of peritoneal than pleural mesothelioma. Men are at greater risk because of their prevalence in workplaces that used asbestos.
Young women, in particular, make up most cases of multicystic and well-differentiated peritoneal mesothelioma. Experts don’t know why, but they suspect fibromatosis, a benign growth that affects women, may be a contributing factor.[1]
The good news for women with these types of peritoneal mesothelioma is that they are not aggressive and rarely metastasize. Surgery is often curative.
What Are the Symptoms of Peritoneal Mesothelioma?
The symptoms of peritoneal mesothelioma may not be obvious, or they may be mild and not show until many years, even decades, after asbestos exposure. Significant and harmful delays in diagnosis often occur for this reason. Peritoneal mesothelioma may cause:[5]
- Ascites, fluid build-up, and swelling in the abdomen
- Abdominal pain
- Unintentional and unexplained weight loss
- Diarrhea
- Constipation
- Bowel obstruction
- Anemia
- Fever
- Fatigue
- Nausea
- Vomiting
How Is Peritoneal Mesothelioma Diagnosed?
The early symptoms of peritoneal mesothelioma make it challenging to diagnose. They are similar to symptoms of irritable bowel syndrome, Crohn’s disease, colitis, and other more common gastrointestinal disorders.
Doctors are more likely to diagnose these first, leading to a misdiagnosis. This is especially likely if they are unaware of any asbestos exposure a patient may have experienced.
The first step in getting an accurate diagnosis is a physical exam and a thorough history. Tell your healthcare provider if you have or think you may have experienced asbestos exposure. These steps will follow a physical exam in most cases:[6]
- After reviewing your symptoms and performing a physical exam, your doctor may start ordering imaging studies, usually beginning with a simple X-ray or CT scan. These studies can help identify peritoneal changes, such as thickening of the lining or a tumor mass, to suggest the presence of cancer. Other specialized imaging, such as MRI or PET/CT scans, is usually ordered by specialty providers and may take place after a biopsy.
- A blood test may also be used to determine if you have any tumor markers, any substances that are associated with cancer.
- If there are visible abnormalities on a scan, a biopsy is used to determine a diagnosis. This is usually done by an interventional radiologist, a specialist trained in both reading imaging scans and performing minimally invasive biopsies. Most biopsies can be performed at a local hospital, with patients going home the same day.
- In some cases, a more invasive surgical biopsy may be necessary. This happens when the tissue in question is difficult to reach, or the routine biopsy cannot gather enough cells to give your medical team a firm diagnosis.
At this point, a surgeon will usually recommend a laparoscopy in the operating room under general anesthesia. This allows the surgeon to use a camera to look inside the abdominal cavity, looking for any signs of cancer, and choose the best location to biopsy.
Laparoscopy is an excellent instrument by which the surgeon can directly visualize tumors within the abdomen and pelvis and also facilitate a biopsy of a cancerous nodule. However, it has been associated with mesothelioma growing out of the insertion site for the telescope. This is referred to as port site metastases.
In order to avoid this very serious dissemination of mesothelioma to the abdominal wall, laparoscopy for mesothelioma must only be performed through the absolute midline of the abdomen. Usually, the telescope is placed just above or below the umbilicus. If cancer grows out at a midline port site, it can be excised without excessive damage to the muscles, nerves, and fascia that make up the abdominal wall.
Staging Peritoneal Mesothelioma
Staging cancer is important for giving patients an estimated prognosis or life expectancy and for informing treatment. Due to its rarity, peritoneal mesothelioma has no official staging system.
Many doctors rely on the TNM system used for pleural mesothelioma to designate a stage:[7]
- Stage 1. Tumors are only in the peritoneum and are limited.
- Stage 2. By stage 2, tumors have grown and spread but have still not invaded the lymph nodes.
- Stage 3. When tumors spread outside the peritoneum or invade the lymph nodes, the stage is often labeled as 3.
- Stage4. Stage 4 mesothelioma is metastatic. This means it has spread to distant parts of the body.
Can Peritoneal Mesothelioma Be Misdiagnosed?
Peritoneal mesothelioma is extremely rare, and most doctors–even oncologists–have no experience with it. The symptoms can be vague and similar to other illnesses, and many people don’t have past exposure to asbestos as a clue.
For all these reasons, misdiagnosis is common. Typical misdiagnoses include hernia, irritable bowel syndrome, Crohn’s disease, colitis, ovarian cysts or cancer, and other types of abdominal cancer.
It’s essential that you seek a second opinion if you don’t feel good about a diagnosis you receive. If doctors have ruled out more common illnesses, see an oncologist or mesothelioma specialist.
How Is Peritoneal Mesothelioma Treated?
Treatment options for peritoneal mesothelioma include the standard therapies of surgery and chemotherapy. Radiation is seldom indicated. There are, as well, some new and experimental therapies.
Oncologists, especially those who specifically work with mesothelioma patients, are best suited to plan your treatments. They will most likely recommend a combination of therapies based on your cancer’s stage, your health and age, and your preferences.[7]
Cytoreductive Surgery and HIPEC
A newer, innovative treatment has been used with more success in patients with peritoneal mesothelioma and is now the standard therapy. It is called cytoreductive surgery plus HIPEC, or heated intraperitoneal chemotherapy:[8]
- Cytoreductive surgery. The first step in this procedure is a radical surgery to remove as much cancerous tissue as possible. Complete removal gives the best results.
- Heated chemotherapy. Then, heated chemotherapy drugs are administered directly into the abdomen at the end of surgery.
Chemotherapy
Some patients are not good candidates for surgery and may benefit from systemic chemotherapy. A typical first-line treatment combination is pemetrexed with cisplatin or carboplatin.
Although not as effective as surgery with HIPEC, systemic chemotherapy extends life expectancy for patients with peritoneal mesothelioma.
Advances in Immunotherapy
Researchers at MD Anderson Cancer Center recently reported positive results in clinical trials using immunotherapy drugs for peritoneal mesothelioma patients. These medications enhance the immune system in various ways to help target cancer cell death.
In a phase II clinical trial, the researcher got a positive response in 40% of participants. It extended survival time in these patients. The treatment also proved safe. This trial used the combination of atezolizumab and bevacizumab.[9]
Can Peritoneal Mesothelioma Be Cured?
All cases of mesothelioma are considered incurable, but some patients survive for many years and may be considered cured. This outcome is more likely in peritoneal than pleural mesothelioma.
One reason is that peritoneal mesothelioma spreads less aggressively. It also responds well to the novel HIPEC treatment after cytoreductive surgery, which has not yet been found to be beneficial to pleural patients.
Who Are the Leading Peritoneal Mesothelioma Doctors?
Paul Sugarbaker, M.D.
Dr. Paul Sugarbaker is one of the world’s leading experts on peritoneal mesothelioma. He also specializes in treating cancers that have metastasized to the peritoneum. He is the Chief of the Peritoneal Surface Malignancy Program at Washington, D.C.’s Washington Hospital Center. He is also the Director of the Center for Gastrointestinal Malignancies.
During his career, Dr. Sugarbaker has worked both in clinical practice and research, including a decade as a Senior Investigator at the National Cancer Institute. He pioneered a treatment strategy for peritoneal mesothelioma, now known as the Sugarbaker Procedure. It involves using cytoreductive surgery followed by circulating heated chemotherapy drugs (HIPEC) throughout the abdominal cavity. The procedure is now used widely and has helped extend the life expectancy of many peritoneal cancer patients.
Kiran Turaga, M.D.
Dr. Kiran Turaga is a surgical oncologist with a special interest in treating advanced malignancies, including metastatic cancers (cancers that have spread beyond their original site to other parts of the body). Dr. Turaga has published widely on peritoneal mesothelioma.
He is the Division Chief of Surgical Oncology at Yale School of Medicine. He recently constructed a working group to provide multidisciplinary recommendations for the treatment of peritoneal mesothelioma. His guidelines were developed with input from leading experts, including surgical oncologists, medical oncologists, pathologists, radiologists, palliative care physicians, and pharmacists. His work has increased awareness of this disease and provided appropriate management strategies for malignant peritoneal mesothelioma.
Dr. Turaga is an expert in regional perfusion, including hyperthermic intraperitoneal chemotherapy (HIPEC), a technique that delivers high doses of heated chemotherapy directly to abdominal organs to kill cancer cells that may remain after surgical removal of visible tumors.
Andrew Blakely, M.D.
Dr. Andrew Blakely is a surgical oncologist specializing in peritoneal surface and retroperitoneal malignancies. A primary focus of his research is to develop novel treatment approaches and modalities to improve pre-operative treatment of peritoneal carcinomatosis.
Currently, Dr. Blakely is a Senior Investigator at the Surgery Branch of the National Cancer Institute in Bethesda, Maryland. He is the surgeon designated to work with the multidisciplinary team at the National Institutes of Health on clinical and research studies in malignant peritoneal mesothelioma. Protocols for managing peritoneal mesothelioma are open at the National Institutes of Health and promise to bring new information to bear on this rare disease.
David Bartlett, M.D.
Dr. David Bartlett is currently a Professor of Surgery and Director of the Surgical Oncology Program at the Allegheny Medical and Surgical Network. He has extensive experience treating peritoneal mesothelioma, beginning two decades ago at the National Institutes of Health.
He has published his data on the management of peritoneal mesothelioma widely in the peer-reviewed literature and is currently engaged in clinical and experimental research on this disease.
Dr. Bartlett served as a Senior Investigator at the Surgery Division of the Center for Cancer Research at the National Cancer Institute, where he developed innovative surgical techniques to treat patients with peritoneal metastases. He is currently President of the Society of Surgical Oncology.
What Are the Best Treatment Centers for Peritoneal Mesothelioma?
To get the best outcome for this rare disease, you need specialist treatment. Not many oncologists or surgeons specialize in peritoneal mesothelioma. You may need to travel to one of these renowned cancer centers for the best treatment options:
- MD Anderson Cancer Center, Houston, Texas
- Washington Cancer Institute, Washington, D.C.
- The University of Chicago Comprehensive Cancer Center, Chicago, Illinois
- Herbert Irving Comprehensive Cancer Center, New York City
How Long Can I Live with Peritoneal Mesothelioma?
The prognosis for peritoneal mesothelioma is generally poor given the aggressive nature of the disease. However, it is usually much better than the outlook for pleural mesothelioma. Overall prognosis improves if you are a candidate for cytoreductive surgery plus HIPEC.[10]
Several factors determine each patient’s prognosis:
- Age and health
- Gender
- Stage of the cancer at diagnosis
- Treatments chosen
- Concerning radiological features on CT identified by an experienced radiologist.
For peritoneal mesothelioma, the median survival time without disease progression–that is, the time a patient lives from diagnosis with no further worsening of the disease–is just 13.9 months.[10]
By stage, the five-year survival rates for peritoneal mesothelioma are:[7]
- Stage 1 – 87%
- Stage 2 – 53%
- Stage 3 – 29%
How to Improve Prognosis
The best chance you have of a good prognosis for peritoneal mesothelioma is with an early diagnosis. Finding out about it in the early stages gives you more treatment options. Aggressive, early treatments can increase the amount of time patients spend without visible cancer and allow patients to feel good longer.
It is essential to discuss the potential risks and complications with your medical care team to ensure you make an informed decision. Selecting a team with experience in treating mesothelioma can be highly beneficial.
The best survival rates are seen with patients who undergo cytoreductive surgery plus HIPEC. A 2017 study involved twenty-nine mesothelioma patients who received surgery followed by heated chemotherapy. Nearly three-quarters of the patients lived longer than five years after treatment, a big improvement in overall survival times.[8]
Getting a diagnosis for peritoneal mesothelioma may be devastating, but you have options and hope. You may get a second opinion and then seek treatment at a Peritoneal Surface Oncology center.
You can choose from aggressive treatments and those that will make you feel more comfortable in the time you have left. You may also be able to file a lawsuit to seek compensation if you were exposed to asbestos in the workplace.
Frequently Asked Questions
