Mesothelioma Cancer

Mesothelioma is a type of cancer that originates in the lining of certain organs. It most commonly occurs in the lungs, but can also be found in the heart, digestive tract, or testes. Asbestos exposure is the only known risk factor for this rare but aggressive form of cancer.

The overall survival rate for mesothelioma is low, but treatments can help to extend patients’ lives and make them more comfortable. Several promising research studies are underway on new treatment methods, which could make a significant difference for patients and their families.

An immunotherapy treatment called nivolumab is already approved in Japan for use in certain patients with malignant pleural mesothelioma. A three-year follow-up study released in March 2021 demonstrated an overall survival rate of 23.5%. These promising results are being followed up with additional research, including combining this drug with others.

What causes mesothelioma?

Most cases of mesothelioma are associated with asbestos exposure. This is a mineral that has been commonly used in certain industries because it’s resistant to heat and fire. People in certain occupations have a greater risk of being exposed to asbestos fibers, including:

• Construction workers
• Plumbers
• Firefighters
• Shipyard workers
• Power plant workers
• Asbestos Miners
• Automotive Mechanics
• Workers who manufacture or install insulation
• Factory workers

Although the use of asbestos in the United States has declined in the decades since its strong link to cancer was discovered, asbestos is still legal and can still be used under certain circumstances. There is often a long period between asbestos exposure and the development of cancer; this period is usually about 20 to 40 years but can be even longer.

An asbestos fiber is far smaller than a human hair. The size of an asbestos fiber is generally between 0.1 and 10 microns, while human hair averages 75 microns. The particles in wood smoke are of a similar size to asbestos fibers. However, unlike smoke, asbestos has no smell or taste, so detecting without equipment is challenging.

What are the different types of mesothelioma?

Mesothelioma arises from a type of tissue called mesothelium, which forms a membrane around certain body organs. These membranes help to create a smooth surface to allow for the normal movement of organs such as the lungs, heart, and digestive tract.

There are two different ways to classify mesothelioma. One way is by the location where the cancer arises. These types include:

• Pleural mesothelioma, which affects the pleura, the membrane around the lungs. This is by far the most common type of mesothelioma, accounting for more than 75% of cases. 
• Peritoneal mesothelioma, affects the peritoneum, the membrane around the digestive tract. This accounts for most of the remaining cases.
• Pericardial mesothelioma, affects the pericardium, the membrane around the heart. This type is rare, accounting for fewer than 1% of all cases.

Very rarely, mesothelioma may be found in the tunica vaginalis, the membrane around the testes. This accounts for fewer than 1% of all cases.

In addition to the location, there is another way to categorize the types of mesothelioma. This is related to the type of cells found in the cancer.

• Epithelioid mesothelioma accounts for more than half of all diagnoses. Although these cells grow faster, they do not spread as easily. This is why this type of mesothelioma tends to be more treatable.
• Sarcomatoid mesothelioma accounts for 10-20% of cases. It originates from the middle layer of cells in the mesothelium. This type tends to be more aggressive, as it can spread more easily.
• Biphasic mesothelioma accounts for the remaining 20-30% of cases, and contains both cell types. Its characteristics are intermediate between the other two types.

Symptoms of Mesothelioma

The symptoms of mesothelioma depend on which type the patient has. Malignant pleural mesothelioma patients may have various symptoms, including:

• Cough (usually painful)
• Shortness of breath
• Chest pain
• Weight loss
• Lumps felt under the skin

For peritoneal mesothelioma, the symptoms are different, and may include:

• Abdominal pain
• Nausea
• Swelling of the abdomen
• Weight loss

Many of these symptoms can also be caused by a variety of other diseases (including other types of lung cancer), so your doctor will need to do some tests to get the correct diagnosis.

How is mesothelioma diagnosed?

Your doctor will perform an exam and run some tests to eliminate other diseases and confirm a diagnosis of malignant pleural mesothelioma. A chest X-ray is commonly used in the early stages of diagnosis; the finding of a mass in the chest strongly suggests cancer but does not show which type of cancer it is. Some patients have a pleural effusion, which is a buildup of fluid around the lungs; a sample of this fluid may contain cancer cells, although the absence of cells in the fluid does not rule out cancer.

For peritoneal mesothelioma, testing may include imaging of the abdomen (usually through a CT scan), along with blood tests to rule out other causes of the symptoms. The finding of a mass on the CT scan will trigger further evaluation. Some patients may have fluid in the abdomen (known as ascites, or a peritoneal effusion); again, a sample of this fluid may contain cancer cells, which would make the diagnosis clear.

Procedure for mesothelioma biopsy

A definitive mesothelioma diagnosis generally requires a biopsy, which is a small sample of the tissue. There are a few different ways to get this sample, and which one is used for a particular patient depends on the location of the tumor.

If it’s close enough to the surface, the tissue sample may be obtained using a needle inserted through your skin. This often works for pleural mesothelioma, as the primary tumor usually forms close to the chest wall, but can sometimes be more difficult for other types.

The biopsy may also be done using an endoscope, which is a long flexible tube with a camera on the end. For example, in cases of peritoneal mesothelioma, the endoscope can be inserted into the digestive tract through the mouth or the anus, allowing access to the tumor. In more complex cases, a surgical procedure might be needed for the biopsy.

The sample of tissue is sent to a laboratory, which analyzes the cells for specific abnormalities that indicate a malignancy. This will determine whether a patient has mesothelioma, and if so, what type of mesothelioma.

Research is underway to discover a less invasive method for diagnosing malignant pleural mesothelioma in its early stages. While blood tests have not proven useful, breath tests have shown promise in early studies. One particular breath test demonstrated an accuracy of 97% in detecting MPM. More research is needed to refine the technique, but this could offer a noninvasive way to screen for mesothelioma and diagnose it in its early stages when it’s more treatable.

What do the stages of mesothelioma mean?

With any type of malignancy, once a diagnosis is reached, then staging is the next step. The stage of cancer refers to how far the cancer has spread within the body. Of the various forms of mesothelioma, malignant pleural mesothelioma is the only one with a formal system of staging.

• Stage 1 cancers remain in the area where they originated.
• Stage 2 and 3 cancers have spread to lymph nodes near the area where it originated and/or to nearby structures (such as into the chest wall), but have not spread farther than that.
• Stage 4 cancers have spread to other organs of the body. 

To determine what stage a patient’s mesothelioma is in, doctors may use various tests, including an MRI, a CT scan, an echocardiogram, and/or a PET scan. Other tests, including blood tests and lung function tests, may help to show how much the cancer has affected the functioning of the lungs and other internal organs.

What is the life expectancy for mesothelioma?

Overall, the prognosis for patients with malignant pleural mesothelioma is poor. On average, the 5-year survival rate for this form of cancer is only 10%. It does vary according to the stage of the cancer and what treatments the patient receives. 5-year survival rates may be as high as 18% for those with localized tumors, and as low as 7% for those whose tumors have already spread to other organs.

On average, life expectancy for patients with malignant pleural mesothelioma is 12 to 21 months, depending on the stage of the cancer. For younger patients with early-stage cancers, life expectancy may be somewhat longer. Treatments may help to extend this, but usually only by a few months. Keep in mind that this is an average; individual patients may live for a longer or shorter amount of time after diagnosis.

What Mesothelioma Treatments Are There?

Although it carries a poor prognosis overall, treatment of malignant pleural mesothelioma can be helpful for some patients. As with other types of cancer treatment, patients are often referred to a cancer center, where they have access to the full spectrum of care. Rather than a single mesothelioma specialist, patients are usually treated by a team of doctors, which may include a medical oncologist, a radiation oncologist, a thoracic surgeon, and/or a pulmonologist.

Combinations of treatments are often used to get the best possible results. Some patients have treatment with the goal of eliminating the cancer. However, this is unfortunately not a realistic goal for many patients with mesothelioma. When a cure is unlikely to be possible, then palliative care can help patients stay more comfortable during their remaining time and may prolong their life somewhat.

Current treatments for mesothelioma

Surgery may be helpful for some patients. Various types of surgery may be used for mesothelioma. The most invasive surgery is called extrapleural pneumonectomy (EPP). This procedure removes the lung on the affected side along with all of the tissues that contact the lung (including the pleura, part of the diaphragm, and often the pericardium around the heart). This is a major surgical procedure and is generally only performed in cases where it may be curative (a localized epithelioid tumor).

Less invasive surgeries include pleurectomy/decortication; this removes the pleura, but not the lung itself. In an extended version of this surgery, part of the diaphragm may also be removed. This is less extensive, and it may be used as a curative procedure in patients with very early cancers, or as a palliative procedure in others. Another option is debulking, which removes as much of the cancer as possible, to address symptoms related to the tumor. This is a palliative procedure rather than a curative one.

Radiation can also be used. This is generally external beam radiation therapy (EBRT), which uses an X-ray machine to deliver radiation. Other forms of radiation therapy exist, but their use in mesothelioma is still experimental.

Chemotherapy is sometimes used, typically in combination with other treatments. This may be given to the whole body through an IV (systemic chemotherapy), or it may be injected into the space where the cancer is (intrapleural or intraperitoneal chemotherapy). Chemotherapy is usually combined with surgery and/or radiation therapy; chemotherapy alone has not shown good results.

Clinical trials for mesothelioma

In addition, there are multiple research trials underway, testing various experimental treatments for mesothelioma. One example is immunotherapy, which aims to stimulate the patient’s immune system to destroy the cancer cells. Some of these trials show promise, and more effective treatment options may become available to patients in the future. 

If you’re interested in trying an experimental treatment, the only way is to enroll in a clinical trial. This can be an option for certain patients, but you’ll need to find out which trials you would be eligible for and carefully think through the risks and benefits of enrolling in a trial. We recommend that you talk with your doctor to discuss this option. 

To find out what trials are currently being run, you can check the database maintained by the National Cancer Institute (NCI), which is part of the National Institutes of Health (NIH).

What support is available for mesothelioma patients?

Patients with mesothelioma and their loved ones may benefit from community support. Caregivers need to ensure that they have enough support so that they won’t burn out. Support groups can be helpful for many people.

For many patients and their family members, mesothelioma causes a significant financial and emotional burden. If your mesothelioma was caused by exposure to asbestos, then you may be eligible to receive compensation, which can help to relieve some of this burden.

If you have a loved one who has passed due to mesothelioma, you may also be eligible for compensation. Talk with a lawyer to find out more about your rights.

Frequently Asked Questions

Below are some commonly asked questions we receive from patients and family members regarding mesothelioma diagnosis, finding treatment or steps in taking legal action.