Straight Talk about Mesothelioma, a blog series created by Michael T. Milano, M.D., Ph.D., a radiation oncology specialist, as a resource for mesothelioma patients and their loved ones.
The majority of mesotheliomas develop in the pleural lining of the lung, although there are other places in the body mesothelioma can develop.
Just as the lung has an outer lining called the pleura, the inside of the abdominal cavity is also lined with a layer, called the “peritoneum.” This peritoneal layer is made up of the same type of cells that make up the pleura – mesothelial cells (hence the name: mesothelioma). The primary function of the peritoneum is to ensure that there is no friction between the abdominal organs. A secondary function, is to secrete fluids that lubricate the abdominal cavity. There are many blood vessels and nerves which run throughout the peritoneum.
So, What Is Malignant Peritoneal Mesothelioma?
Like the pleura, the peritoneum can also develop mesothelioma, which we all know to be an extremely deadly cancer. In the U.S., there are about 300-500 cases a year – and with this low incidence rate, the disease is classified in the medical community as an “Orphan Disease.”
The cancer develops years after the asbestos fibers are inhaled. First, these fibers cross through the chest cavity and, once through, they can enter the peritoneum. If the fibers lodge themselves into this lining, they can incite an inflammatory reaction. Over time, there is a change in the DNA of the mesothelial cells and, as a result, cancer develops. There are some people who develop peritoneal mesothelioma after swallowing asbestos fibers.
The unfortunate truth is: malignant peritoneal mesothelioma is a very aggressive tumor and is usually fatal. Globally, the incidence rate of this tumor has increased over the past 2 decades, primarily in developed countries, like the U.S., where asbestos is still used. Peritoneal mesothelioma is slightly more common in men (since, historically, they were the ones who worked in the asbestos industry) and tends to present itself after the 5th decade of life.
What Are the Symptoms of Peritoneal Mesothelioma?
Unfortunately, the symptoms of peritoneal mesothelioma are often vague and occur decades – 20-50 years – after one’s exposure to asbestos. Though the signs and symptoms are subtle, a patient with peritoneal mesothelioma may complain of the following:
- Abdominal Pain or Discomfort
- Loss of Appetite
Peritoneal mesothelioma can cause fluid accumulation in the abdomen which gives the sensation of bloating. Peritoneal mesothelioma can also present itself with other features, such as low blood sugar, blood clots, a high number of platelets, and a significant loss of muscle mass. In most patients, peritoneal mesothelioma remains confined to the abdominal cavity. However, in some people, it may spread to the bone, lungs, liver, and lymph nodes. In order to make the diagnosis, the healthcare provider must obtain a history of prior asbestos exposure.
What Goes into a Diagnosis of Peritoneal Mesothelioma?
Routine laboratory tests are of no help in the diagnosis. Some specific blood tests have been developed to help diagnose peritoneal mesothelioma, but they are not sensitive or routinely used. In most cases, the tumor has extensively spread by the time a diagnosis is made.
A CT scan will usually show a lesion (of any size) in the peritoneum. In addition, the abdominal cavity will also contain fluid (called “ascites”). While there may be cancer cells floating in this fluid, often there is not. To confirm the diagnosis of peritoneal mesothelioma, a needle biopsy of the peritoneum is obtained and the tissue is analyzed under a microscope by a pathologist. Very rarely the diagnosis may be made by the surgeon who is performing surgery to determine why the patient is having pain.
Treatment & Prognosis of Peritoneal Mesothelioma
Once the diagnosis of peritoneal mesothelioma is made, there are several options for treatment. Surgery has the highest success rate, but often the patients are in poor physical shape and not able to easily tolerate general anesthesia.
Peritoneal mesothelioma, like pleural mesothelioma, is very resistant to radiation and chemotherapy. Other treatment options include hyperthermic intraperitoneal chemotherapy (HIPEC). For patients who are fit, surgery should be the first option, as it can usually achieve complete removal.
Systemic use of cancer drugs is often done, but the cancer frequently remains unresponsive – especially if it is late stage (Stage 3 or 4). Radiation is almost never used, as peritoneal mesothelioma is unresponsive to the dose of radiation that could be safely used. Today, researchers are studying the role of immunological therapies to treat this cancer.
If the peritoneal mesothelioma is discovered early enough, those patients who have been treated with surgery have been reported to survive 1-2 years. There are some reported cases of patients who have survived 3-19 years.