Pleural Mesothelioma Malignant

Pleural mesothelioma malignant is a rare and aggressive cancer that develops in the tissue lining the lungs and chest wall, almost always linked to asbestos exposure that may have occurred decades earlier.

Table of contents

• What Is Malignant Pleural Mesothelioma?
• Types of Pleural Mesothelioma
• How Common Is This Cancer?
• What Causes Pleural Mesothelioma?
• Signs and Symptoms
• How Is It Diagnosed?
• Cancer Stages
• Treatment Options
• Outlook and Life Expectancy
• Prevention

What Is Malignant Pleural Mesothelioma?

Malignant pleural mesothelioma is a rare cancer that grows in the pleura, which is the thin membrane that lines the walls of your chest and covers your lungs^[1]. The condition gets its name from the mesothelium, a protective lining that covers your internal organs. When cancer forms in any part of the mesothelium, it is called mesothelioma^[1].

This cancer is aggressive and fast-growing. It forms in the tissue that covers many internal organs, with the lung lining being the most commonly affected area^[5]. The disease is strongly associated with asbestos exposure, and there is often a long delay between exposure and the appearance of symptoms^[3].

Pleural mesothelioma is the most common type of mesothelioma, accounting for about 80% of all mesothelioma diagnoses^[1]. While the cancer is not curable in most cases, treatments such as surgery, radiation therapy, chemotherapy, and immunotherapy can potentially extend life and improve quality of life^[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^[1]. The cell type affects how aggressive the cancer is and how well it might respond to treatment.

Epithelioid mesothelioma is the most common form, making up 60% to 80% of cases. It is the easiest type to treat and tends to respond better to treatment than other types^[1][9].

Sarcomatoid mesothelioma is the rarest form, accounting for about 10% of cases. It grows faster and is harder to treat than epithelioid mesothelioma. This type is usually aggressive, meaning it grows and spreads quickly^[1][9].

Biphasic mesothelioma is a rare form that makes up 10% to 15% of cases. It contains a mix of both epithelioid and sarcomatoid cell types. The aggressiveness of this type depends on the ratio of epithelioid to sarcomatoid cells. The more epithelioid cells present, the more likely the cancer is to respond to treatment^[1][9].

How Common Is This Cancer?

Mesothelioma is a rare disease. Approximately 3,300 people in the United States receive a mesothelioma diagnosis each year^[1]. Pleural mesothelioma accounts for about 80% of these diagnoses, making it the most common type of mesothelioma^[1].

Widespread efforts to reduce asbestos exposure have led to a decline in cases in the United States since 2000^[1]. According to recent data, there were 666 cases of malignant mesothelioma diagnosed in Australia in 2009, and around 90% of them originated in the pleura^[14].

Men are affected more often than women. The average age at diagnosis is 60 years^[7]. Older veterans make up 30% of mesothelioma cases due to exposure in the military ship, vehicle, and plane industry^[7].

What Causes Pleural Mesothelioma?

Asbestos exposure causes pleural mesothelioma in 70% of cases, though the actual number may be higher^[1]. Exposure to asbestos is the primary cause of this disease, responsible for about 80% to 90% of all mesothelioma cases^[4].

Asbestos is a group of minerals naturally found in rocks and soil that form long, thin, very strong fibers. These fibers do not evaporate or dissolve in water, resist heat and fire, and cannot be broken down easily by chemicals or bacteria^[4]. Asbestos was once 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. If you inhale these particles, they settle in your lungs. They are too tough for your body to break down. Over time, these particles cause scarring and inflammation in your lungs and also cause cell changes that lead to cancer^[1]. Inhaling asbestos fibers can lead to repeated inflammation in the pleura, disruption of how cells divide, activation of genes that promote cancer growth, and generation of harmful substances called free radicals^[3].

It usually takes a long time for malignant mesothelioma to form after asbestos exposure. It can take up to 50 years for pleural mesothelioma to develop after asbestos exposure^[1]. Most people develop the condition about 20 to 50 years after being in contact with asbestos^[7].

Other risk factors include ionizing radiation, such as radiation therapy used for Hodgkin lymphoma, and genetic factors, including mutations in a gene called BAP1^[3]. Living with a person who works with asbestos is also a risk factor^[6]. Smoking itself does not directly cause pleural mesothelioma, but combined smoking and asbestos exposure significantly increases the risk of lung cancer^[3].

Most people with malignant mesothelioma have worked or lived in places where they inhaled or swallowed asbestos. Working with materials that contain asbestos can release tiny asbestos fibers, too small to see, into the air^[4]. Intact materials containing asbestos are safe. Asbestos only poses a health risk when disturbing the material releases asbestos particles into the air^[1].

Signs and Symptoms

The symptoms of pleural mesothelioma develop slowly. Early signs can be bothersome but easy to dismiss. Many people delay seeing their healthcare provider until their cancer is more advanced^[1]. Symptoms may not appear until 20 to 40 years or longer after exposure to asbestos^[7].

The main symptoms of pleural mesothelioma are ongoing chest pain and shortness of breath^[1]. These symptoms can be caused by fluid that collects in the chest. Sometimes the cancer causes fluid to build up in the chest or abdomen^[6].

Other symptoms include:

• Persistent cough and hoarseness^[1]
• Painful coughing^[5]
• Difficulty swallowing^[1]
• Lower back pain^[1]
• Swollen face and arms^[1]
• Lumps under the skin on the chest^[5]
• Unexplained weight loss^[1]
• Night sweats^[1]
• Fatigue^[1]
• Fever^[1]

This aggressive cancer causes the pleura to thicken, preventing the lungs and chest from expanding normally. As a result, fluid may build up in the chest cavity. People with malignant pleural mesothelioma often develop shortness of breath, a dry cough, and chest pain^[9].

If you have any of these symptoms, talk to your doctor. They may be caused by something other than cancer. The only way to know what is causing them is to see your doctor^[4]. It is important for anyone with a history of asbestos exposure to share this information with their doctor if they develop symptoms^[6].

How Is It Diagnosed?

Mesothelioma diagnosis may start with a physical exam. A healthcare professional may check for lumps or other signs^[16]. Tests that examine the inside of the chest and abdomen are used to diagnose malignant mesothelioma^[6].

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^[16]. An X-ray typically reveals fluid in the chest. Many doctors may suspect pneumonia or another inflammatory condition if they don’t immediately inquire about asbestos exposure, which can delay the diagnosis^[9].

Based on the results of imaging tests, you may have more tests to see whether mesothelioma or another disease is causing your symptoms^[16]. Additional tests may include MRI (magnetic resonance imaging) and PET scan (positron emission tomography scan)^[16].

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^[16]. The type of biopsy depends on what area of your body the mesothelioma affects. Your healthcare professional might remove fluid or a piece of tissue with a thin needle inserted through the skin of the chest or belly. A surgeon might take fluid or a tissue sample during surgery by making a small cut and inserting a tube with a video camera to see inside your chest or belly^[16].

The tissue sample goes to a lab for tests. Mesothelioma is often hard to diagnose. Under the microscope, it can be difficult to tell this disease apart from similar conditions and tumors^[7]. Sometimes it is hard to tell the difference between malignant mesothelioma in the chest and lung cancer^[6].

Cancer Stages

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. These tests help determine the extent of the cancer^[16].

Your healthcare professional uses the results of these tests to give your cancer a stage. The stage helps your healthcare professional choose the treatments that are right for you^[16]. The stages of pleural mesothelioma go from 1 to 4. A lower number means the cancer is less advanced^[16].

After malignant mesothelioma has been diagnosed, tests are done to find out if cancer cells have spread to other parts of the body^[6]. Stage 1 is the easiest to treat, while stage 4 is the hardest^[25].

Treatment Options

Treatment depends on where the mesothelioma is located and whether it has spread to other parts of the body^[4]. The treatment you have depends on where your cancer is, how far it has grown or spread, the type of cancer, your general health and level of fitness, and your personal wishes^[13].

Unfortunately, mesothelioma can be difficult to treat. It 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]. There is usually no cure unless the disease is found very early and the tumor can be completely removed with surgery^[7].

Surgery is an option for some patients with early stage mesothelioma if they are fit and well enough. Your surgeon might remove part of the pleura or the whole of the pleura, or as much cancer as possible to relieve symptoms^[13]. Surgery can help some people live longer and may also help control and relieve symptoms^[13].

Chemotherapy uses medicines to shrink or kill cancer cells. The drugs can be pills you take or medicines given through your veins, or sometimes both^[4]. Common chemotherapy drugs for mesothelioma are pemetrexed and cisplatin^[13]. You might have chemotherapy for early stage pleural mesothelioma alongside surgery and radiation therapy, or to shrink or control advanced pleural mesothelioma^[13].

Radiation therapy uses high-energy rays (similar to X-rays) to kill cancer cells^[4]. You might have radiation therapy after surgery for early stage mesothelioma, or to control mesothelioma symptoms and slow down the growth of your cancer^[13].

Immunotherapy is a treatment that uses your immune system to fight cancer. It works by helping the immune system recognize and attack cancer cells^[13]. Special medicines help your body’s immune system fight the cancer^[4]. You might have immunotherapy drugs if you can’t have surgery. Immunotherapy helps to control the cancer and is given as your first treatment, before other treatment such as chemotherapy^[13].

In 2020, a combination of nivolumab and ipilimumab was approved for first-line treatment of unresectable malignant pleural mesothelioma. This combination provided significant improvements in survival compared to standard chemotherapy^[17].

Targeted therapy uses drugs to block the growth and spread of cancer cells. The drugs can be pills you take or medicines given through your veins. You will get tests to see if targeted therapy is right for your cancer type before this treatment is used^[4].

Treatment may also include clinical trials, which test new treatment options^[4]. Participating in a clinical trial may give patients more treatment options^[7].

For patients who are too ill to cope with aggressive treatments, supportive care (also called palliative care) can help relieve symptoms such as pain or breathing problems^[13]. Pain relief, oxygen, and other supportive treatments may help relieve symptoms^[7].

Outlook and Life Expectancy

Pleural mesothelioma is almost always a fatal disease, and the prognosis can only be modestly influenced by treatments^[14]. The average mesothelioma life expectancy with treatment is 12 to 21 months^[23]. Without treatment, most people survive about 9 months^[7].

Treatment extends survival from an average of six months without treatment to 12 months with treatment. Patients diagnosed at an early stage who undergo aggressive treatment may live three to five years or longer^[26]. The five-year survival rate is 10% for all types of mesothelioma cancer^[26].

Several factors affect prognosis, including the stage of cancer, age, general health, the type of cells involved, and how well the cancer responds to treatment^[1][7]. Important prognostic factors identified in large studies include stage, age, performance status (how well you can carry out daily activities), and cell type^[18].

Patients whose mesotheliomas are sarcomatoid or biphasic have a worse prognosis and are generally not candidates for surgical treatment^[17]. 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^[1].

Many patients have lived for years beyond their initial diagnosis with proper treatment. Some people decide to get a second opinion after diagnosis^[6]. Your life expectancy is not set in stone. If you have mesothelioma cancer, treatments like surgery, chemotherapy, and immunotherapy can potentially help you live longer^[23].

Prevention

The best way to prevent pleural mesothelioma is to avoid exposure to asbestos^[7]. Since then, government agencies and manufacturers in the United States have taken steps to reduce asbestos exposure to prevent people from developing mesothelioma^[1].

If you think you may be at risk because of past asbestos exposure, talk to your doctor. Your doctor can help you decide if you should get regular checkups or tests for asbestos-related diseases^[4].

Asbestos was used in many consumer products, automobile parts, and building materials in the 20th century before scientists learned about its dangers to health. Asbestos is no longer mined in the United States, but it is imported from other countries to make some products. It is still present in some older homes and buildings^[4].

Risk factors for mesothelioma include being exposed to asbestos at work, living with someone who works with asbestos, and living or working in a building where materials that contain asbestos have been disturbed^[4].