Peritoneal mesothelioma is a form of mesothelioma that develops in the abdomen, specifically on the peritoneum (the lining of the abdominal cavity). It is extremely rare, accounting for only about 20 percent of all mesothelioma cases annually, or about 660 cases per year in the United States. Patients with peritoneal mesothelioma tend to have a better prognosis than those with other types of mesothelioma.

What Causes Peritoneal Mesothelioma? 

As with all forms of mesothelioma, exposure to asbestos is the only known cause of peritoneal mesothelioma. Asbestos — a cancer-causing mineral — has been used in a number of commercial and residential applications. When asbestos is disturbed, its microscopic fibers become airborne and can enter the body either through inhalation or ingestion.

Peritoneal mesothelioma is likely caused by ingesting (swallowing) asbestos fibers. Because the body has no way of expelling the tiny asbestos fibers, over time they lodge into the lining of the abdomen, causing inflammation and scarring. The body creates excess fluid in the abdomen, in an effort to lubricate the area. This fluid buildup is called ascites. Eventually, this can result in malignant cell mutations and the formation of tumors.

Researchers believe peritoneal mesothelioma may also be caused by inhaled asbestos fibers that travel from the lungs to the abdomen through the lymphatic system — the body’s defense system for getting rid of toxins and fighting off infection.

While peritoneal mesothelioma affects both women and men, the method of exposure often differs. Men commonly face direct occupational exposure, whereas women tend to be exposed indirectly. Because asbestos fibers can travel for miles or be transported on the clothing, skin, or hair, indirect exposure is a threat for those living with people who are exposed to asbestos on the job. Interestingly, peritoneal mesothelioma has been more commonly associated with non-occupational exposure than pleural mesothelioma, which affects the lining of the lungs.

What Are the Symptoms of Peritoneal Mesothelioma?

Mesothelioma Hub - Peritoneal Symptoms
The most common symptoms of peritoneal mesothelioma are abdominal pain and swelling, lumps in the abdomen, and unexplained weight loss. Abdominal fluid buildup, or ascites, is commonly associated with peritoneal mesothelioma. In some cases, ascites can cause mild seizures as a result of accumulated toxins in the body. Additional symptoms include:

  • Anemia
  • Body aches
  • Bowel obstruction
  • Constipation
  • Diarrhea
  • Fatigue
  • Fever or night sweats
  • Hernia
  • Nausea or vomiting

Similar to other forms of mesothelioma, the symptoms of peritoneal mesothelioma can mimic other conditions. Common misdiagnoses include:

  • Colorectal adenocarcinoma
  • Inguinal hernia
  • Irritable bowel syndrome (IBS)
  • Ovarian cancer
  • Primary peritoneal carcinoma
  • Stomach cancer

If you are experiencing any of the above symptoms, talk to your doctor right away. Be sure to inform your doctor if you may have been exposed to asbestos occupationally or perhaps indirectly from someone in your life who worked with or around asbestos.

How Is Peritoneal Mesothelioma Diagnosed?

All forms of mesothelioma take many years to manifest — sometimes upward of 50 years. The period between the original asbestos exposure and when symptoms appear is called the latency period. By the time symptoms begin to appear, the disease has likely advanced or begun to spread. For this reason, it is imperative that you visit a doctor right away upon showing any symptoms and share with them any history you may have with asbestos exposure. This can help guide them in the diagnostic process, especially because mesothelioma is so rare and the symptoms often mirror those of other illnesses.

The diagnostic process for mesothelioma generally starts with a series of imaging tests. X-rays, CAT scans, and MRIs are common. If fluid is present in the abdomen, doctors may also take samples for cytology, or fluid biopsies. Blood tests such as MesoMark® are used to test for the presence of mesothelial cells. A tissue biopsy is often the last step in the process and is the only definitive way to diagnose mesothelioma. Biopsies are helpful for understanding what cell type is present in the tumor — important information when deciding on a treatment plan.

Common biopsies used for diagnosing peritoneal mesothelioma include:

  • Paracentesis — A type of needle biopsy, paracentesis is used to attain a sample of the ascitic fluid from the abdomen. It also serves as a palliative treatment to relieve discomfort caused by the excess fluid buildup.
  • Peritoneoscopy — In this biopsy, a camera is used to help doctors view inside the abdomen, identify which organs are affected, and take a diagnostic sample.
  • Laparotomy — During this surgical procedure, doctors try to remove as much of the tumor as possible. It also serves as a means to collect a sample for further diagnostic analysis.   

Staging Peritoneal Mesothelioma

Since peritoneal mesothelioma is still a very rare condition, there is no formal staging system in place. Oncologists often use the American Joint Committee on Cancer (AJCC) 1–4 staging scale to best determine a stage. The Peritoneal Cancer Index (PCI) is also frequently used for assessing the extent of cancer present, as well as account for any spread to the lymph system or other parts of the body. The PCI score, a range from 0–39, helps determine eligibility for various treatments. A low score generally indicates minimal tumors or spread, equating to a stronger prognosis.

Peritoneal Mesothelioma Prognosis

Location, stage, cell type, patient age, and overall health all contribute to a patient’s prognosis. Due to the treatment options available, peritoneal mesothelioma tends to carry a better prognosis than other forms of the cancer (pleural or pericardial). Advances in treatment have shown increased life expectancy among patients with peritoneal mesothelioma.

Treating Peritoneal Mesothelioma

Mesothelioma is typically treated with a multimodal plan including surgery and chemotherapy. Clinical trials, emerging treatments, and immunotherapy are also being used more commonly to treat mesothelioma.

For patients with peritoneal mesothelioma, the most impactful treatment plans usually include surgery and chemotherapy.

Surgery and chemotherapy for peritoneal mesothelioma

The most common treatment plan for peritoneal mesothelioma is a peritonectomy. This procedure can be done with the intent to completely remove the cancer or to alleviate pain and discomfort, improving the patient’s quality of life. It combines cytoreductive surgery with heated chemotherapy, sometimes called HIPEC (hyperthermic intraperitoneal chemotherapy).

In this procedure, the lining of the abdomen and all of the mesothelial tumors present in the abdomen are removed. The surger is then followed by the administration of a heated chemotherapy wash to remove any remaining cancerous cells. Because the doctor can localize the chemotherapy drugs, reducing the negative impact on other parts of the body, HIPEC allows for a higher dose of chemotherapy to be applied directly to the infected area.

Recent studies have shown that when these two treatments are combined, patients experience survival times between 52 and 92 months.

Peritoneal Mesothelioma Specialists and Treatment Centers

Dr. H. Richard Alexander, Jr. — Surgical oncologist and Chief Surgical Officer at Rutgers Cancer Institute of New Jersey in New Brunswick, New Jersey

Dr. W. Charles Conway — Surgical oncologist at the Ridley-Tree Cancer Center in Santa Barbara, California

Dr. James F. Pingpank Jr. — Oncologist at the UPMC Hillman Cancer Center in Pittsburgh, Pennsylvania

Dr. Suzanne C. Schiffman — Surgical oncologist at the Allegheny General Hospital in Pittsburgh, Pennsylvania

Dr. Paul H. Sugarbaker — Gastrointestinal oncologist at the Washington Cancer Institute in Washington, D.C.