Peritoneal mesothelioma is one of the four primary types of malignant mesothelioma. The name stems from the area where the cancer develops, along the peritoneum, also known as the lining of the abdomen. Roughly 250 to 500 new cases of peritoneal mesothelioma are diagnosed in the U.S. each year, making it the second-most common mesothelioma type.
Name given to the cancer that attacks the lining of the abdomen. This type of cancer affects the lining that protects the contents of the abdomen and which also provides a lubricating fluid to enable the organs to move and work properly.
The peritoneum is made of two parts, the visceral and parietal peritoneum. The visceral peritoneum covers the internal organs and makes up most of the outer layer of the intestinal tract. Covering the abdominal cavity is the parietal peritoneum.
All mesotheliomas, including peritoneal, stem from extended exposure to asbestos, usually at work. People diagnosed with the disease often can pinpoint a time in their lives when they were around asbestos dust, fibers or products for a sustained period. This exposure leads to ingestion or inhalation of microscopic asbestos particles, which can produce cancerous cells and then tumors.
Malignant peritoneal mesothelioma (MPM) is a rare aggressive tumor of the peritoneum, regarded as a universally fatal disease. It is poorly described and the knowledge of its natural history is very limited. Occupational and environmental asbestos exposure still remains a public health problem around the world. The incidence has increased in the past 2 decades. Only 20% to 33% of all mesotheliomas arise from the peritoneum itself; the pleura is the most common site of origin.
Mesotheliomas have 3 basic histologic forms: epithelioid (the most frequent), sarcomatoid or mixed (biphasic). More often, areas showing features and admixtures of these three types may be encountered within a single tumor; a sarcomatoid component is observed in 25% of cases, but a pure sarcomatoid variety is extremely rare and only 32 cases have been reported in the literature since 2006.
Given its rarity, there are no established guidelines for the treatment of peritoneal mesothelioma. The modern approach to malignant peritoneal mesothelioma includes cytoreductive surgery, hyperthermic intraperitoneal chemotherapy (HIPEC), intraperitoneal chemotherapy, and intravenous chemotherapy. These are often use in conjunction and in a complimentary fashion, and this multifaceted approach has significantly improved outcomes when compared to intravenous chemotherapy alone. For instance, the reported median 5-year survival for patients with mesothelioma as reported by the American Cancer Society is 12 months;however, with adequate cytoreduction, intraperitoneal, and intravenous chemotherapy combined, some authors report 10-year survival rates projected at nearly 75%.
Multiple factors have been shown to be significant in predicting a the outcome and overall survival. Age greater than 60 at surgery, more overall disease burden (defined as a PCI greater than 15), complete cytoreduction (no visible disease), and epitheliod subtype pathology have all been shown to be predictors of both mortality and disease progression. These known predictors notwithstanding, many patients with advanced peritoneal mesothelioma are still surgical candidates, and even patients with the highest possible score on the peritoneal carcinomatosis index (39) can be completely reduced to a PCI of 0 with adequate surgery.
Outcome and Prognosis
Mesotheliomas are almost universally considered a fatal neoplasm, and until recently the treatment options were very limited and ineffective. The overall median survival was only 1 year. Nevertheless, a few cases of long-term survivors have been reported (longest survival reported is 19 years).
After the introduction of cytoreductive surgery followed by intraperitoneal hyperthermic perfusion, a significant prolongation in the median survival has been achieved, with approximately half the patients alive at 5 years.[48,62] Tumor histopathology, previous surgical score, lesion size, gender, distribution (assessed with Gilly classification and peritoneal cancer index), and completeness of cytoreduction score, represent the main prognostic index.
Multicystic mesothelioma and well-differentiated peritoneal mesothelioma typically occur in the peritoneum of women without a history of asbestos exposure and show low malignant potential. Multicystic mesothelioma predominantly affects the pelvic peritoneum of young women, has a high tendency to recur locally, but no tendency to metastasis, and consequently requires only surgical treatment. Some theories link this type of mesothelioma to fibromatoses, suggesting a reactive hyperplastic process more than a neoplastic one.A familial form of multicystic mesothelioma has also been described.Sarcomatoid mesothelioma, although rare, is the most aggressive histotype, with a median survival reported of only 3.8 months.