Peritoneal Mesothelioma

Mesothelioma is a terrible diagnosis because it is an aggressive type of cancer that is most often fatal. It is a cancer that attacks the lining of organs in the body, called the mesothelium. The four types of the cancer are characterized by the part of the mesothelium in which the tumors originate. Peritoneal mesothelioma begins with cancer of the peritoneum, the lining of the abdominal organs.

This is the second most common type of mesothelioma, and it accounts for only about 20 percent of all cases. There are only between 250 and 500 diagnoses of peritoneal mesothelioma made each year. Although any type of mesothelioma is rare, by far the most common is pleural mesothelioma. Peritoneal mesothelioma causes symptoms that are often mistaken for conditions like irritable bowel syndrome. Treatment may include chemotherapy, radiation, and surgery, but the outlook is not generally positive.

Cancer of the Peritoneum

The peritoneum is the part of the mesothelium that surrounds and protects abdominal organs like the stomach and intestines. It consists of two layers, the visceral and the parietal peritonea. Either layer can be the origin of mesothelioma tumors. This is an aggressive type of cancer, which means that it spreads easily and quickly. It may first spread from one layer to the other, and from there it may go to organs within the abdominal cavity, like the liver or intestines.

Peritoneal cancer may also spread to the omentum, a layer of fatty tissue over the abdomen. In extremely rare cases—only about five have ever been reported—the cancer may begin in the omentum and then spread to the peritoneum. Both contain mesothelium cells, so the origin of mesothelioma, although rare, may be in the omentum.

Causes and Risk Factors

There is no definitive cause for any type of mesothelioma, let alone this rarer form of the cancer. However, there do seem to be certain risk factors, including genetics and a family history of mesothelioma. The strongest risk factor is exposure to asbestos. The more prolonged the exposure, the greater the risk is, and people who worked around asbestos for decades have the greatest risk.

Although prolonged asbestos exposure is most often associated with pleural mesothelioma, it is also associated with the peritoneal form of the cancer. Most people exposed to asbestos will inhale the fibers, which get lodged in the airways. It is possible also to ingest those fibers, and it is possible that inhaled fibers will get to the abdominal cavity through the lymph nodes. Wherever asbestos ends up, it causes damage, and puts a person at risk for developing mesothelioma.

How Peritoneal Mesothelioma Grows

Peritoneal mesothelioma has an extremely long latency period. This means that in the majority of cases, symptoms of the disease do not begin to present themselves until decades after the initial exposure to asbestos. Though the asbestos fibers begin to do damage as soon as they enter the body, it takes a long time for their impact to be seen.

Asbestos fibers begin by embedding themselves in the cells of the body and killing those cells. They then cause mutations to occur in the cells that surround the dead cells, and these mutated cells eventually grow into tumors. It is not until the tumors grow large enough to put pressure on the organs that surround them.

Symptoms

Like pleural mesothelioma, the symptoms of peritoneal mesothelioma often don’t develop until decades after the initial exposure to asbestos. This means that the latency period is decades long for most patients who eventually get this diagnosis. Some of the common symptoms of peritoneal mesothelioma are pain and swelling in the abdomen, a feeling of fullness, weight loss, anemia, fever, diarrhea, constipation, bowel obstruction, nausea, vomiting, and fatigue.

Diagnosis

Many of the early symptoms of peritoneal mesothelioma make it tough to diagnose. Initially it may seem as if a patient has irritable bowel syndrome, Crohn’s disease, colitis, or other gastrointestinal disorders. It is not uncommon for this very rare type of cancer to be initially misdiagnosed as something much more common and less serious.

Because of the possibility of misdiagnosis, it is important that patients tell their doctors about any asbestos exposure. This is usually a huge clue to look for signs of mesothelioma. Beyond a physical exam, the next step in making a diagnosis is to image the abdomen with X-rays, a CT scan, an MRI, a PET scan, or some combination of these. These scans can give a doctor a good picture of any unusual tissue formations in the abdomen that might be cancerous.

If these abnormalities are spotted in a scan, the next step is to biopsy it. This means removing a small amount of tissue for testing. If it is easy to access, a tumor may be biopsied with a needle, an easy outpatient procedure. If it is more difficult to get to, more invasive, surgical biopsies may be required. It is important that these samples be removed, though, as they often give the best final diagnosis.

Treatment

Treatment for peritoneal mesothelioma may include surgery, chemotherapy, radiation, and other strategies. The treatment plan depends on the patient, the stage of the cancer, and other health concerns. Because peritoneal cancer is so rare, there is no set of defined guidelines for treating it. Most doctors treating peritoneal mesothelioma use a multimodal approach, using a variety of strategies to target the cancerous tissue.

In addition to the more traditional cancer treatments of chemotherapy, radiation therapy, and surgery to remove tumors, a technique called heated intraperitoneal chemotherapy has shown promise in treating peritoneal mesothelioma. This technique involves using surgery and then injecting heated chemotherapy drugs directly into the abdomen. Standard chemotherapy is administered intravenously. Only certain patients meet the requirements for this cutting edge treatment, but it has helped a limited number of patients live longer than expected.

Prognosis

As with any type of mesothelioma the prognosis for peritoneal mesothelioma is generally not very good. Things like extent of exposure to asbestos, age and gender, and staging of the disease all contribute to a prognosis. Only about 25 percent of people with a diagnosis of peritoneal mesothelioma will live for three or more years.

Because prognoses for this disease are so gloomy, an early diagnosis is crucial. The earlier the stage of the cancer is, the greater chance a patient has of living longer. Aggressive treatments can also help improve the prognosis for a patient. Not everyone can withstand the side effects of these treatments, but those who are able to will likely live longer.

Getting a diagnosis for peritoneal mesothelioma may be devastating, but you do have options. You can get a second opinion, and you can choose from among treatments that are aggressive and those that will make you feel more comfortable in the time you have left.