Peritoneal mesothelioma arises from the membrane around the digestive system, which is called the peritoneum. This is the second most common type of malignant mesothelioma. Although the overall survival rate is fairly low, it can be significantly improved by treatment with surgery and chemotherapy.
How common is peritoneal mesothelioma?
Malignant peritoneal mesothelioma is the second most common type of malignant mesothelioma, after malignant pleural mesothelioma (which forms in the membrane around the lungs). Peritoneal mesothelioma accounts for fewer than 20% of all mesothelioma diagnoses. There are around 300 to 400 cases of peritoneal mesothelioma diagnosed each year in the US.
Did you know?
In the US, about half of peritoneal mesothelioma patients are women and half are men. This is different from pleural mesothelioma, which is diagnosed in men about 80% of the time.
What causes peritoneal mesothelioma?
The only known risk factor for peritoneal mesothelioma is exposure to asbestos. This is a mineral that has been used in certain industries for many years because it’s heat-resistant and fire-resistant.
Asbestos fibers are extremely tiny, and inhaling them can lead to them being deposited in the lungs, where they cause pleural mesothelioma. If the fibers are then coughed up and swallowed, they can lead to peritoneal mesothelioma. Alternatively, the fibers may be trapped in mucus or saliva and then swallowed.
Not every case of peritoneal mesothelioma is caused by asbestos exposure. In studies, between 33 and 50% of peritoneal mesothelioma cases can be linked to known asbestos exposure. The other one-half to two-thirds of cases have an unknown cause.
Some of these cases might be linked to asbestos exposure that the patient is unaware of, or to exposure to another mesothelioma-causing mineral (such as erionite). However, we don’t always know what causes a particular case of peritoneal mesothelioma.
What are the symptoms of peritoneal mesothelioma?
The symptoms of peritoneal mesothelioma can be similar to those of other illnesses, which can make it hard to distinguish this type of cancer based on symptoms alone. The symptoms may include:
- Abdominal pain
- Nausea
- Swelling of the abdomen
- Loss of appetite
- Change in bowel habits (diarrhea or constipation)
- Weight loss
- Night sweats
- Fever
Did you know?
It can take a long time to get an accurate diagnosis. One study showed that the average time between the onset of symptoms and the time of diagnosis was over four and a half months. This is because the symptoms of peritoneal mesothelioma are similar to those of many other diseases, and mesothelioma is fairly rare.
How is a peritoneal mesothelioma diagnosis made?
To distinguish peritoneal mesothelioma from other diseases and get an accurate diagnosis, doctors need to do some testing. Usually, a few different tests are performed, including imaging tests, a biopsy, and sometimes blood tests.
Imaging for peritoneal mesothelioma
In most cases, the diagnostic process begins with a CT scan of the abdomen. This type of scan uses X-rays to construct a three-dimensional image of the abdomen. It’s relatively quick to perform and will allow a doctor to visualize any tumors that are present.
Finding one or more tumors on a CT scan is a very strong indication that a patient has mesothelioma cancer, but it doesn’t show what type of cancer it is. Further testing is necessary to determine the type of cancer and to find out what stage it’s in. This involves a biopsy and may involve additional imaging.
Sometimes, a PET scan is used to check whether peritoneal mesothelioma has spread to any other area of the body. For this test, a tracer is injected. The scan then looks for places where the tracer is more concentrated.
The most active tissues will have the most tracer; cancer cells are very active cells, so they tend to have a lot of tracer. Using a PET scan can help doctors see whether the cancer has spread to areas outside of the abdomen.
Biopsy for peritoneal mesothelioma
To be certain of the diagnosis, a biopsy is needed. This is a small sample of tissue taken from the tumor. This is sent to a laboratory, where doctors examine it under a microscope and use various types of tests to determine what kind of cancer cells are present.
The biopsy can be done in a few different ways, depending on the location of the tumor. If tumor tissue is located very close to the skin, then doctors sometimes do a fine needle biopsy, where a needle is passed through the skin and into the tumor to get the sample. However, in many cases of peritoneal mesothelioma, this isn’t possible.
In most cases, the biopsy for peritoneal mesothelioma is performed during an exploratory surgery called a laparoscopy. In this procedure, the surgeon makes a few small incisions in the skin of the abdomen. A long flexible tube with a camera and a light on the end is inserted. By watching the image from the camera on a monitor, the surgeon can look around the abdominal cavity. A biopsy can be obtained, and the surgeon can also look at the organs of the abdomen to check for tumors.
Immunochemistry for peritoneal mesothelioma
In addition to the other tests, a blood test known as immunochemistry can be useful in ensuring that the diagnosis is correct, including the specific cell type of the mesothelioma (epithelioid, sarcomatoid, or biphasic). This test looks for specific proteins in the blood; different proteins are produced by different types of cancer cells. Immunochemistry testing is not as useful in peritoneal mesothelioma as in pleural mesothelioma, but it can still help confirm the diagnosis or in determining the patient’s response to treatment.
Staging of peritoneal mesothelioma
The stage of cancer refers to how far it has spread within the body and is an indication of how advanced the disease is. For many other cancers (including malignant pleural mesothelioma), the stage of the cancer is determined by whether it’s spread to lymph nodes, to nearby structures of the body, or to more distant organs.
However, staging for malignant peritoneal mesothelioma is somewhat more complicated. For this disease, the cancer cells don’t usually spread to lymph nodes, or through the bloodstream to distant organs. Instead, they tend to spread around the abdomen, growing in various places on the peritoneum, the membrane around the digestive organs. The presence of multiple tumors growing on the peritoneum is called peritoneal carcinomatosis and is a sign of a more advanced disease.
There is no formal system of staging for peritoneal mesothelioma. A few different systems have been developed, but there is no single one that’s accepted as the standard. Instead, doctors may describe specific characteristics of cancer, including whether peritoneal carcinomatosis is present and how many tumors are found within the abdomen, as well as whether there’s any evidence of more distant disease.
What are the treatments for peritoneal mesothelioma?
The treatment for peritoneal mesothelioma can vary, depending on the stage that the cancer is in at the time of diagnosis and the cell type of the cancer. Each peritoneal mesothelioma patient will have a treatment plan created by their team for their situation. However, treatment commonly includes surgery and chemotherapy.
Cytoreductive surgery
The most common type of surgery for peritoneal mesothelioma is called cytoreductive surgery. During this procedure, the peritoneum itself will be removed (including the greater omentum, which drapes over the front of the abdominal cavity). In addition, any visible cancer tissue will also be removed. Parts of several different abdominal organs may be removed during cytoreductive surgery, including the stomach, gallbladder, ovaries, uterus, and intestines.
Hyperthermic intraperitoneal chemotherapy
Also known as heated intraperitoneal chemotherapy, or HIPEC, this technique is almost always included with cytoreductive surgery. After the removal of as much cancer tissue as possible, then a heated chemotherapy solution is infused into the abdominal cavity. This is left in place for about two hours and then washed out.
Because the chemotherapy is placed directly into the abdomen (rather than into the bloodstream through an IV), there are generally fewer side effects from this procedure than from traditional chemotherapy. Some of the chemotherapy medications may be absorbed through the organs of the abdomen, and so patients may experience some side effects. Still, it’s much less toxic than traditional chemotherapy.
Radiation therapy
Although it’s used in other forms of mesothelioma, radiation therapy is not commonly used as a curative treatment for peritoneal mesothelioma, because there are usually multiple different tumors present. In certain cases, radiation may be used for palliative care, to help shrink a particular tumor that is causing symptoms.
Immunotherapy
Immunotherapy is a form of treatment that has shown great promise in other types of cancer, including pleural mesothelioma. This type of treatment uses the patient’s immune system to destroy the cancer cells. The treatment may stimulate the immune system in general, or it may act on cancer cells in ways that target them for destruction by the immune system.
Although there are currently two different immunotherapy treatments that are approved for pleural mesothelioma, the use of immunotherapy for peritoneal mesothelioma is still in its experimental stages. A peritoneal mesothelioma patient who wants to try immunotherapy will need to enroll in a clinical trial. This is a research study that tests a new experimental therapy. Patients who are interested in this option should discuss it with their doctors, as there are risks and benefits to being a part of a clinical trial.
What is the prognosis for peritoneal mesothelioma?
As with other types of mesothelioma, the prognosis tends to be relatively poor overall. On average, the 5-year overall survival rate for peritoneal mesothelioma is about 18%, although some patients have a better chance of survival (for instance, those who are younger than 50 at the time of diagnosis, who have up to a 40% chance of surviving for five years).
Life expectancy at the time of diagnosis ranges from 2 to 15 years, depending on the characteristics of the cancer and other patient factors.
Did you know?
A recent study of 184 patients with malignant peritoneal mesothelioma demonstrated the effectiveness of cytoreductive surgery with HIPEC. In the study, patients who received this treatment had a 5-year overall survival rate of 77.8%. This is significantly higher than the average for this malignancy.
What resources are available for patients with peritoneal mesothelioma?
For patients who have this rare type of cancer, getting connected with the right resources is crucial. This can help you to navigate the journey of cancer treatment and may help to ease the burden of a mesothelioma diagnosis.
Cancer centers
Because this is an uncommon type of cancer, it’s generally best to be treated at a cancer center. This gives you access to experts who are familiar with the latest research in the field.
Cytoreductive surgery is a very complex procedure, and the outcomes are generally best if it’s performed by a surgeon with extensive experience in this particular surgery. At a cancer center, you’re more likely to find a surgeon who has a high level of skill in performing cytoreductive surgery.
Clinical trials for peritoneal mesothelioma
Some patients may choose to enroll in a clinical trial. This is a research study that tests a particular treatment for the disease. Patients who choose to be a part of a clinical trial may gain early access to treatments that could be lifesaving, and they may find a sense of purpose in helping others by contributing to scientific research. At the same time, there’s no guarantee that the new treatments will be more effective than the old ones, and patients may have to accept being randomized to receive the new treatment or a placebo (an inactive substance used for comparison).
If you’d like to explore the option of being part of a clinical trial, then we recommend that you discuss this option with your doctor first. The National Cancer Institute maintains a database of clinical trials that are currently enrolling patients, so you can search there to learn what trials you might be eligible for.
Legal resources for peritoneal mesothelioma
In some cases, peritoneal mesothelioma is caused by asbestos exposure. Exposure may occur in the workplace, and workers may also expose those they live with via asbestos fibers brought home on their clothes, skin, and hair. Some people have also been exposed to asbestos via contaminated talcum powder products.
If you or a loved one have developed mesothelioma from asbestos exposure, then you may be entitled to financial compensation. Some lawyers focus on holding companies accountable for the harm that they’ve caused by exposing workers and/or customers to asbestos. We recommend that you seek legal advice from an experienced mesothelioma lawyer.
Support groups for peritoneal mesothelioma
Along with the financial burden, mesothelioma patients, along with their families and caregivers, often experience a significant emotional burden. Support groups can help connect with others who are going through a similar experience. This can help you feel more confident and provide comfort as you navigate this challenging journey.
There is hope for peritoneal mesothelioma patients
Although peritoneal mesothelioma tends to be an aggressive type of cancer, treatments can help to extend many patients’ lives. In addition, there is promising new research that may lead to better treatments in the future. If you or your loved one has been diagnosed with peritoneal mesothelioma, we recommend taking advantage of the many resources available for people with this disease.
