Pleural Mesothelioma

Pleural mesothelioma is a rare and aggressive cancer that forms in the lining of the lungs and chest wall, caused primarily by asbestos exposure, often decades before symptoms appear.

Table of contents

• What Is Pleural Mesothelioma?
• Causes and Risk Factors
• Types of Pleural Mesothelioma
• Symptoms
• Diagnosis
• Treatment Options
• Prognosis and Life Expectancy
• Prevention
• Living With Pleural Mesothelioma

What Is Pleural Mesothelioma?

Pleural mesothelioma is a rare cancer that develops in the pleura, the thin layer of tissue that lines the chest cavity and covers the lungs^[1]. This cancer gets its name from the mesothelium, a protective lining that covers many internal organs. When cancer forms in any part of the mesothelium, it is called mesothelioma^[1].

• Lungs
• Chest wall
• Pleura (lung lining)

Pleural mesothelioma is the most common type of mesothelioma. Approximately 3,300 people in the United States receive a mesothelioma diagnosis each year, with pleural mesothelioma accounting for about 80% to 90% of these cases^[1][5]. The disease affects the tissue around the lungs and is strongly associated with asbestos exposure^[3].

Widespread efforts to reduce asbestos exposure have led to a decline in cases in the United States since 2000^[1]. However, because of the long time between exposure and disease development, new cases continue to appear.

Causes and Risk Factors

Asbestos exposure causes pleural mesothelioma in 70% of cases, and the actual number may be higher^[1]. More than 80% of mesothelioma cases overall are caused by exposure to asbestos^[8]. Asbestos is a group of minerals that was once widely used in many industries, including building and manufacturing. Until the 1960s and 1970s, workers mined asbestos in the United States^[1].

Asbestos consists of fibers that become tiny, airborne particles when disturbed. When you inhale these particles, they settle in your lungs. These particles are too tough for your body to break down. Over time, they can cause scarring and inflammation in your lungs and also cause cell changes that lead to cancer^[1]. The process involves repeated inflammation of the pleura, disruption of cellular division, activation of cancer-causing genes, and the generation of harmful substances called free radicals^[7].

Important risk factors include working or living in places where asbestos was present. Most people with malignant mesothelioma have worked or lived in places where they inhaled or swallowed asbestos^[12]. Living with a person who works near asbestos is also a risk factor^[12]. Washing the clothing of someone who worked with asbestos also increases risk^[8].

Other risk factors include exposure to ionizing radiation (such as mantle radiation therapy used for treating certain cancers) and genetic factors. Some studies suggest links with mutations in a gene called BRCA1-associated protein 1 (BAP1)^[7]. Notably, smoking does not directly cause pleural mesothelioma, although combined smoking and asbestos exposure significantly increases the risk of lung cancer^[7].

Intact materials containing asbestos are safe. Asbestos only poses a health risk when disturbing the material releases asbestos particles into the air^[1].

Types of Pleural Mesothelioma

In 2015, the World Health Organization classified mesothelioma into three categories based on the types of cells where the cancer develops. Some cell types lead to more aggressive (fast-growing) cancer than others^[1].

Epithelioid mesothelioma is the most common form, accounting for 60% to 80% of cases. It is the easiest type to treat^[1].

Sarcomatoid mesothelioma is the rarest form, making up about 10% of cases. It grows faster and is harder to treat than epithelioid mesothelioma^[1].

Biphasic mesothelioma is a rare form accounting for 10% to 15% of cases. It contains a mix of epithelioid and sarcomatoid cell types^[1].

The type of pleural mesothelioma you have will help your healthcare provider determine what treatments may work best and what your likely outcome might be. Patients whose mesotheliomas are sarcomatoid or biphasic generally have a worse outlook and are usually not candidates for surgical intervention^[17].

Symptoms

The symptoms of pleural mesothelioma develop slowly. It can take up to 50 years for pleural mesothelioma to develop after asbestos exposure. Early signs can be bothersome but easy to dismiss. Many people delay seeing their healthcare provider until their cancer is more advanced^[1]. After asbestos exposure and the onset of cancer, there is generally a separation of about 40 years^[8].

The main symptoms of pleural mesothelioma are ongoing chest pain and shortness of breath^[1][4]. Shortness of breath may occur due to fluid buildup around the lung^[4].

Other symptoms include:

• Persistent cough and hoarseness
• Difficulty swallowing
• Lower back pain
• Swollen face and arms
• Unexplained weight loss
• Night sweats
• Tiredness or fatigue
• Fever
• Lumps under the skin on the chest

Sometimes the cancer causes fluid to collect in the chest. Signs and symptoms may be caused by the fluid, the cancer itself, or other conditions^[12].

Diagnosis

It can be hard to tell the difference between mesothelioma and other cancers or lung conditions. Mesothelioma diagnosis may start with a physical exam where a healthcare professional checks for lumps or other signs^[11].

You might have imaging tests to look for mesothelioma. These could include a chest X-ray and a CT scan (computed tomography scan) of your chest or belly^[11]. Other imaging tests may include MRI (magnetic resonance imaging) and PET scan (positron emission tomography scan)^[11].

A biopsy is a procedure to remove a sample of tissue for testing in a lab. Biopsy is the only way to confirm or rule out mesothelioma^[11]. The type of biopsy depends on what area of your body the mesothelioma affects. Biopsy procedures may include putting a needle through the skin to remove fluid or tissue, or taking a sample during surgery. A surgeon might make a small cut and insert a tube with a video camera to see inside your chest and pass tools through the tube to get a tissue sample^[11].

The tissue sample goes to a lab for tests using techniques like immunohistochemistry to determine whether the tissue is mesothelioma and what type it is. Once your healthcare professional confirms mesothelioma, you may have other tests to find whether your cancer has spread to your lymph nodes or to other areas of your body^[11].

Your healthcare professional uses the results of these tests to give your cancer a stage. The stages of pleural mesothelioma go from 1 to 4. A lower number means the cancer is less advanced^[11]. The stage helps determine which treatments may be right for you.

Treatment Options

Pleural mesothelioma is not curable, but treatments like surgery, radiation therapy, chemotherapy and immunotherapy can potentially extend your life^[1]. Treatment options depend on where the cancer is located, how far it has grown or spread, the type of cancer, your general health and fitness level, and your personal wishes^[13].

Unfortunately, mesothelioma can be difficult to treat and is often diagnosed at an advanced stage. Nearly all treatments aim to control the mesothelioma for as long as possible and keep symptoms under control^[13].

Immunotherapy

Immunotherapy uses the immune system to fight cancer. It works by helping the immune system recognize and attack cancer cells. You might have immunotherapy drugs if you cannot have surgery. Immunotherapy helps to control the cancer and is given as a first treatment before other treatments like chemotherapy^[13].

In 2020, the combination of nivolumab plus ipilimumab was approved for first-line treatment of unresectable pleural mesothelioma. This combination provided significant improvements in overall survival compared to standard chemotherapy. Two-year survival rates were 41% with nivolumab plus ipilimumab compared to 27% with chemotherapy^[17]. Immune checkpoint inhibition targeting specific proteins is now considered first-line treatment^[9].

Chemotherapy

Chemotherapy uses anti-cancer drugs to destroy cancer cells. The drugs circulate throughout the body in your bloodstream. You might have chemotherapy for early stage pleural mesothelioma alongside surgery and radiation therapy, or to shrink or control advanced pleural mesothelioma^[13].

Common chemotherapy drugs for mesothelioma are pemetrexed and cisplatin^[13]. Chemotherapy often includes the medications cisplatin and pemetrexed together^[4]. This combination has been the standard of care for two decades^[15].

Surgery

Surgery is not a common treatment for mesothelioma because it can be difficult to remove all the cancer. To have surgery, you have to be fairly fit and well so that you can recover without too many problems^[13]. Surgery is reasonable for patients with disease confined to the pleural space^[17].

Your surgeon might remove part of the pleura, the whole pleura, or as much cancer as possible to relieve symptoms^[13]. Surgery might also help you live longer. Some people have achieved long-term survival after aggressive treatment combining surgery with other approaches^[5].

Radiation Therapy

Radiation therapy uses high-energy rays to destroy cancer cells. You might have radiation therapy after surgery for early stage mesothelioma or to control symptoms and slow down the growth of your cancer^[13].

Clinical Trials

Clinical trials use new treatment options. Your doctor might ask if you would like to take part in a clinical trial. Doctors and researchers conduct trials to improve treatments and find new ways to help patients^[13]. Clinical trials may include newer approaches like targeted therapy, which uses drugs to block the growth and spread of cancer cells^[3].

Supportive Care

Mesothelioma is often diagnosed when it is quite advanced. Some people might be too ill to cope with aggressive treatments. However, you can still have treatment to relieve symptoms such as pain or breathing problems. This is called palliative care^[13].

Palliative care is managed by a team of doctors and nurses who are experts in controlling symptoms of advanced cancer. The team might also include a physiotherapist and dietician^[13]. A procedure called pleurodesis, which involves using substances like talc to scar together the pleura, may be used to prevent more fluid from building up around the lungs^[4].

Prognosis and Life Expectancy

Pleural mesothelioma is a fast-growing and deadly form of cancer. For many people with mesothelioma, there is no cure^[4]. However, treatments are available that may improve survival and quality of life.

The average life expectancy with mesothelioma is 12 to 21 months with treatment^[23]. For patients who do not receive treatment, the median survival time is six months^[5]. However, certain types of treatment can improve life expectancy, such as surgery combined with chemotherapy^[5].

Several factors affect prognosis and treatment options. These include the stage of the cancer, the cell type, your age, your overall health and fitness, and how you respond to treatment^[12]. The type of pleural mesothelioma you have will help your healthcare provider determine what your prognosis or likely outcome might be^[1].

Some patients have achieved long-term survival after aggressive treatment. Many factors influence mesothelioma life expectancy, and each patient’s experience is unique. Your life expectancy is not set in stone^[23].

Prevention

Prevention focuses on reducing exposure to asbestos^[4]. Mesothelioma is a 100% preventable cancer. Understanding the dangers of asbestos and risk factors of exposure can help you determine your risk^[24].

Since government agencies and manufacturers in the United States have taken steps to reduce asbestos exposure since scientists discovered the link between exposure and mesothelioma in the 1960s and 1970s, cases have declined^[1]. Asbestos is no longer mined in the United States, but it is imported from other countries to make some products and is still present in some older homes and buildings^[3].

Working with materials that contain asbestos can release tiny asbestos fibers into the air. If you are concerned about past exposure, ask your doctor if you should get regular checkups or tests for asbestos-related diseases^[3]. Not everyone who is exposed to asbestos will develop mesothelioma or other cancers^[3].

Living With Pleural Mesothelioma

Finding out that you have advanced cancer or cannot be cured is distressing and can be a shock. It is common to feel uncertain and anxious, and it is normal to not be able to think about anything else^[26].

Many people find it helpful to find out more about their cancer and the treatments they might have. Knowing more about your situation can make it easier to cope. Talk to your doctor or specialist nurse to understand what your diagnosis means, what is likely to happen, what treatment is available, how treatment can help you, and what the side effects might be^[26].

You can get emotional and practical support through your hospital, local programs, and healthcare providers. Support organizations and charities can give you information and help you connect with other people with mesothelioma^[26].

Patients are usually weak after surgery, chemotherapy, and radiation. Good supportive care and regular nutritional assessment are important. Patients should be referred to a nutritionist. Beginning physical activity as soon as possible is important to prevent complications^[17].

Getting a second opinion, connecting with specialists, maintaining a positive attitude, and having a strong support system are strategies that may help improve your experience and outcomes^[19].