Peritoneal mesothelioma is a rare and aggressive cancer originating in the peritoneum. This thin, protective membrane lines the abdominal cavity and covers organs like the liver and intestines. As a malignant cancer, its cells grow uncontrollably, harming surrounding healthy tissue. It is the second most common type of mesothelioma, accounting for 10% to 30% of all cases.
Causes and Risk Factors
The primary cause of peritoneal mesothelioma is asbestos exposure. Asbestos is a group of naturally occurring fibrous minerals widely used in construction and other industries for their heat resistance and durability. When microscopic asbestos fibers are inhaled or swallowed, they can travel through the digestive or lymphatic system and become trapped in peritoneal tissue.
Over many years, these trapped fibers irritate peritoneal cells, leading to chronic inflammation and cellular damage. This irritation can result in DNA mutations and the development of cancerous mesothelial cells, which form tumors. The latency period, the time between initial asbestos exposure and diagnosis, ranges from 20 to 50 years. While asbestos exposure is the most recognized cause, 20% to 40% of peritoneal mesothelioma cases occur without a known history of asbestos exposure. Other risk factors include genetic predisposition and prior abdominal radiation therapy.
Symptoms and Diagnosis
Peritoneal mesothelioma often presents with subtle, non-specific symptoms, leading to delays in diagnosis. Common symptoms include abdominal pain, swelling due to fluid buildup (ascites), and changes in bowel habits like constipation or diarrhea. Patients may also experience unexplained weight loss, loss of appetite, nausea, vomiting, fatigue, or night sweats. These symptoms can be vague and resemble other abdominal conditions, such as ovarian cancer or irritable bowel syndrome.
Diagnosis begins with a physical examination, where a doctor might notice abdominal distension or tenderness. Imaging tests then visualize the abdominal cavity and identify abnormalities. A computed tomography (CT) scan commonly looks for peritoneal thickening, masses, or fluid accumulation. Magnetic resonance imaging (MRI) and positron emission tomography (PET) scans provide more detailed images or detect cancer spread. If fluid is present, paracentesis may drain and analyze it, though its diagnostic value for definitive confirmation is limited. The only way to definitively confirm peritoneal mesothelioma and determine the specific cell type is through a tissue biopsy. This involves taking a small sample of suspicious tissue, often via laparoscopy, and examining it under a microscope. Identifying the cell type—epithelioid, sarcomatoid, or biphasic—is important as it influences treatment decisions and prognosis.
Available Treatment Approaches
Treatment for peritoneal mesothelioma often involves a multi-modal approach, combining different therapies for the best outcome. A standard treatment for eligible patients is cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC). Cytoreductive surgery, also known as debulking surgery, aims to remove as much visible cancerous tissue and affected peritoneum as possible. The goal is to leave no visible tumor behind, which improves outcomes.
Immediately following CRS, HIPEC is performed. This procedure circulates a heated chemotherapy solution directly into the abdominal cavity for 60 to 120 minutes, at temperatures between 104°F and 109°F (40°C to 43°C). Heating the drugs enhances their absorption by cancer cells and kills remaining microscopic cells. This direct application allows higher chemotherapy doses to the affected area with reduced systemic side effects compared to traditional intravenous chemotherapy. For patients not candidates for aggressive surgery, or as an additional treatment, systemic chemotherapy may be used. This involves administering anti-cancer drugs intravenously, targeting cancer cells throughout the body. Immunotherapy, a newer approach, uses drugs to boost the body’s immune system to fight cancer cells. Palliative care also manages symptoms like pain, nausea, and fluid buildup, improving quality of life. Radiation therapy is less common as a primary treatment due to abdominal organ sensitivity, but may be used for symptom control.
Prognosis and Life Expectancy
Prognosis for peritoneal mesothelioma is influenced by several factors. These include cancer spread at diagnosis, the patient’s overall health and ability to tolerate aggressive treatments, and the tumor’s specific cell type. Peritoneal mesothelioma has three main cell types: epithelioid, sarcomatoid, and biphasic. Epithelioid cells are the most common (50% to 70% of cases) and have a better prognosis and greater responsiveness to treatment. Sarcomatoid cells are less common and more aggressive, leading to a poorer outlook. Biphasic tumors contain a mixture of both epithelioid and sarcomatoid cells, with prognosis depending on the predominant type.
With modern, aggressive treatments like cytoreductive surgery combined with HIPEC, average life expectancy has significantly improved. Studies indicate a median overall survival of 31 to 53 months (2.5 to 4.5 years) for treated patients. Some patients, especially those with epithelioid cell type and successful complete cytoreduction, achieve long-term survival, living 15 years or more. Without treatment, life expectancy is much shorter, ranging from 6 to 12 months. These statistics represent averages, and individual outcomes vary widely based on patient characteristics and response to therapy.