Peritoneal Mesothelioma

A thin membrane of mesothelial cells, known as the peritoneum envelops many of the organs in the abdomen. Peritoneal mesothelioma is a tumor that is on this membrane. Its only known cause is exposure to asbestos, and because it can lay dormant for many years it is not detected until the tumor has begun to grow. Peritoneal mesothelioma accounts for about one-fifth of all mesothelioma cases.

Like any cancer, peritoneal mesothelioma can be either benign or malignant. Mesothelioma is sometimes diagnosed by chance, before any symptoms have appeared. For example, the tumor is sometimes seen on a routine abdominal x-ray for a check-up or before surgery.

The symptoms of peritoneal mesothelioma typically include abdominal pains, weakness, weight loss, loss of appetite, nausea, and abdominal swelling. Fluid often accumulates in the peritoneal space, a condition known as ascites. Over time the symptoms can become more and more severe.

The growing tumor can exert increasing pressure on the organs in the abdomen, leading to bowel obstruction and distention. If the tumor presses upward, it can limit breathing. The tumor may push against areas with many nerve fibers, and the bowel distends, the amount of pain can increase.

X-rays and CT scans are, typically, the first step towards detecting peritoneal mesothelioma. The actual diagnosis is achieved by obtaining a piece of tissue. The procedure of looking at the peritoneum is known as a peritoneoscopy and requires anesthesia. If an abnormality is seen, the doctor will attempt to obtain a tissue sample - this procedure is called a biopsy. A pathologist will make a diagnosis by a microscopic analysis of specialized stains.

There are at least two explanations for how asbestos fibers can get into the peritoneum. The first is that fibers caught by the mucus of the trachea and bronchi are swallowed. Some fibers lodge in the intestinal tract and from there they can move through the intestinal wall into the peritoneum. The second explanation is that fibers that lodge in the lungs can move into the lymphatic system and be transported to the peritoneum.

Medical science does not know exactly how or why, at a cellular level, a carcinogen like asbestos causes a cell to become cancerous. It is not known whether only one fiber can cause a tumor to develop or whether it takes many fibers, or what the exact conditions and predisposition are for this change to happen.

At this time there are treatments, but no known cure, for peritoneal mesothelioma. The prognosis depends on various factors, including the size and stage of the tumor, its extent, the cell type, and whether or not the tumor responds to treatment.

However, the options for relief and treatment of people with peritoneal mesothelioma have improved, especially for those whose cancer is diagnosed early and treated vigorously. Many people receive a combination of therapies, or multimodal therapy. Specific types of treatment include chemotherapy and other drug-based therapies, radiation therapy, and surgery. There are also clinical trials and various experimental treatments like gene therapy and immunotherapy, and antiangiogenesis drugs.