Peritoneal mesothelioma is a type of cancer caused by exposure to asbestos. It happens when the asbestos fibers irritate the lining of the abdominal wall and inner organs of the abdomen so much that cancer cells form.
Understanding Peritoneal Mesothelioma
Peritoneal mesothelioma is not very common. It accounts for only about 10-20 percent of all incidents of mesothelioma. Rather than causing cancer of the lining of the lungs, the cancer develops in the lining of the abdomen, called the peritoneum. In the case of peritoneal mesothelioma, the asbestos fibers are likely taken in by the stomach where they travel to other parts of the abdomen to cause cancer. Veterans are more likely to develop the disease because they have had exposure to asbestos as part of their military career.
What is the peritoneum?
The peritoneum is a protective membrane found around the abdominal organs. There are two layers — the visceral layer, which surrounds the organs, and the parietal layer, which lines the abdominal cavity. Mesothelioma can occur in either layer of the peritoneum.
Why does peritoneal mesothelioma occur?
No one knows exactly how the asbestos fibers get to the peritoneum. Experts believe that the fibers get to the abdomen by swallowing asbestos fibers or by inhaling the fibers that then travel to the abdomen through the lymph system. The lymphatic system is part of the immune system that collects and stores foreign invaders, such as bacteria, viruses, and foreign bodies.
Symptoms of Peritoneal Mesothelioma
The symptoms of peritoneal mesothelioma depend on where the cancer has begun. In the early stages, there might only be:
- Abdominal pain
- Swelling from extra fluid in the abdomen
Often there are no symptoms or only nonspecific symptoms until the cancer has advanced. In such cases, there may be unexplained weight loss and fatigue caused by the cancer. When the cancer has spread, it is harder to cure.
Later signs of peritoneal cancer include:
- Night sweats
- Fullness in the abdomen
- Nausea and/or vomiting
- Weight loss
- Anemia (low blood count)
Remember that it takes up to 50-60 years between the time of exposure to asbestos and the development of cancer. The asbestos fibers remain in the lining of the abdomen for many years before the irritation causes peritoneal mesothelioma.
Diagnosis of Peritoneal Mesothelioma
It can take months to properly diagnose peritoneal mesothelioma, which accounts for about 10-20 percent of all mesothelioma diagnoses. Doctors may begin to look for peritoneal mesothelioma if you have abdominal symptoms and a history of exposure to asbestos, even if it was many decades ago. If you were in the military from World War II and onward, there is a chance that you were exposed to asbestos, especially if you worked in construction or in naval shipyards.
A chest X-ray or CT scan of the abdomen or chest may show areas where tumors might be present. They look like thickened areas of the lining around the organs or the abdominal cavity. Extra fluid might show up on the CT scan of the abdomen. This is a natural reaction to having irritation in the peritoneal lining.
If an area of thickening is found, the doctor may choose to do a biopsy. In a biopsy, a sample of tissue is taken from the peritoneal lining where it has thickened or where nodules (lumps) have formed. Only a biopsy showing mesothelioma cells can effectively diagnose mesothelioma.
Obtaining a Biopsy
Patients with pleural mesothelioma have an easier time diagnosing mesothelioma. Usually, a thoracoscopy is done, which involves using a camera at the end of a long tube and tools that can take a piece of tissue from the pleural lining. In the peritoneum, mesothelioma can be more difficult to diagnose.
A thin needle can be inserted into the fluid of the abdomen so that thousands of cells from inside the fluid can be drawn out and looked at under the microscope. Often, cancerous cells will be in the peritoneal fluid. This can diagnose peritoneal mesothelioma accurately up to 84 percent of the time.
Other methods of getting biopsies of possibly cancerous areas are called endoscopic biopsies, which use a camera and small tools inside the abdominal spaces to look for and sample for cancer. Laparoscopy involves a camera inserted into the abdomen, similar to a thoracoscopy, so that cancerous cells can be found and the area removed to be looked at under the microscope. Alternatively, the biopsy can be taken by doing open surgery on the abdomen and looking for possible cancerous areas.
Treatment of Peritoneal Mesothelioma
Most people who have peritoneal mesothelioma aren’t diagnosed until later stages of the disease, when the cancer has spread to many areas of the abdomen and the rest of the body. Surgery can be done along with chemotherapy and radiation to try and reduce the number of cancer cells in the body.
There is one newer type of treatment for peritoneal mesothelioma that is giving some people hope to live for several years after being diagnosed with cancer. It is called the cytoreduction with HIPEC procedure. HIPEC stands for “hyperthermic intraperitoneal chemotherapy.” In this treatment, all visible signs of cancer are removed from the abdomen with surgery and heated chemotherapy agents are put inside the abdomen to kill any remaining cells. Some people who have had this procedure have lived for up to five years afterward.
Patients in stage 1 or stage 2 of their disease live longer and have more treatment choices than people with the more advanced stage 3 or stage 4 diagnosis. Your prognosis depends on the stage you are in when the disease is diagnosed, your health, the cell type found in the mesothelioma, and the treatments you are eligible for. About 25 percent of all peritoneal mesothelioma patients will live for three years with the best treatment possible. Because treatment is so important to the length of survival, it is important to find a mesothelioma doctor who has treated many cases of mesothelioma in the past.
Surgery for Peritoneal Mesothelioma
Surgery to remove visible signs of cancer is the first step in mesothelioma treatment. It is much more effective for early stage disease than it is for late stage disease. If the surgery is designed to be curative, all areas affected with cancer are removed. If the surgery is designed to be palliative, only those parts of the cancer that are causing the most symptoms are removed, but much of the cancer is left behind. Palliative surgery can relieve pain and other symptoms of advanced mesothelioma.
Common surgeries done for peritoneal mesothelioma include:
- Cytoreductive surgery—this aims to remove as many cancerous cells as possible.
- Peritonectomy—this tries to remove the cancerous cells and the lining around cancerous cells.
- Bowel resection—this removes parts of the intestines that have advanced cancer on them.
- Organ removal—this can involve removal of the spleen, kidneys, stomach or liver affected by cancer.
Chemotherapy and Radiation for Peritoneal Mesothelioma
Chemotherapy can kill cancer cells that cannot be seen by the naked eye. It may be given before surgery, during surgery or after surgery for cancer. Common chemotherapy drugs for peritoneal mesothelioma include cisplatin, carboplatin, pemetrexed, and gemcitabine.
HIPEC is a type of chemotherapy that uses heated chemicals, which are considered more active against the cancer.
While radiation can shrink areas of cancer and can kill cancer cells, it is risky to do this in the entire abdomen. Radiation cannot tell the difference between cancer cells and healthy cells so it may do more harm than good to the abdominal organs.
You can be a part of new and alternative therapies for mesothelioma, especially if you are treated at one of the top mesothelioma centers in the country. In a clinical trial, a new procedure or treatment is tested to see if it can help control the disease better than existing treatments.