Mesothelioma: Full guide

What is mesothelioma?

Mesothelioma is a rare cancer that starts in the thin lining that covers some organs. This lining is called the mesothelium. Most often, mesothelioma starts in the lining around the lungs and inside the chest wall, called the pleura. This is called pleural mesothelioma. Less often, it starts in the lining of the belly, called the peritoneum.

The main cause is breathing in or swallowing asbestos. Asbestos is a mineral that was used for many years in buildings, ships, car brakes, insulation, and factories. The tiny fibers can stay in the body and slowly cause damage. Mesothelioma usually shows up 20 to 50 years after the exposure. Family members of workers can also be exposed from dust on clothes. Some people never know how they were exposed.

Pleural mesothelioma often causes fluid to build up around the lung. This is called a pleural effusion. It can cause shortness of breath, chest pain, a dry cough, tiredness, and weight loss. Peritoneal mesothelioma can cause belly swelling, belly pain, and feeling full quickly.

Mesothelioma is most common in older adults, especially men who worked with asbestos. It is usually hard to cure, because it is often found after it has spread along the lining. But treatment can help people feel better and live longer, and newer immune treatments have made a real difference.

Types

Pleural mesothelioma

The most common type, making up about 8 out of 10 cases. It starts in the lining of the chest and lungs. It often causes fluid around the lung and shortness of breath.

Peritoneal mesothelioma

Starts in the lining of the belly. It makes up most of the rest of cases. It can cause belly swelling and pain. Some people are treated with surgery and heated chemotherapy placed in the belly.

Rare sites

Very rarely, mesothelioma starts in the lining around the heart (pericardial) or around the testicles (tunica vaginalis).

Epithelioid

The most common cell type under the microscope, seen in about 6 or 7 out of 10 people. It tends to grow more slowly and to respond better to treatment.

Sarcomatoid

A less common cell type that tends to grow faster. It responds poorly to chemotherapy alone, but immune treatment with nivolumab and ipilimumab can help.

Biphasic (mixed)

A mix of epithelioid and sarcomatoid cells. How it acts depends partly on how much of each type is present.

Mesothelioma in situ

A very early form found only in the surface layer of the lining. It is rare and usually found by chance.

Tests you may have

Chest X-ray and CT scan

Often the first tests. They can show fluid around the lung or thickening of the pleura. A CT scan of the chest and belly shows where the cancer is.

Thoracentesis

A needle is placed between the ribs to drain fluid from around the lung. This often helps breathing right away. The fluid is checked for cancer cells, but this test alone often cannot confirm mesothelioma.

Pleural biopsy (thoracoscopy)

The most reliable way to diagnose pleural mesothelioma. A surgeon or lung doctor uses a small camera through a cut in the side of the chest to look inside and take tissue. Fluid can be drained and talc placed at the same time to stop it from coming back.

Belly biopsy (laparoscopy)

For peritoneal mesothelioma, a camera is placed through small cuts in the belly to look and take tissue.

PET-CT scan

Shows active cancer spots and whether cancer has spread to lymph nodes or other organs. It helps with staging and surgery planning.

MRI

Can show whether the cancer has grown into the chest wall, diaphragm, or spine. It is used mostly when surgery is being considered.

Lymph node sampling (EBUS or mediastinoscopy)

Tests that take samples from lymph nodes in the middle of the chest, usually before surgery.

Breathing and heart tests

Lung function tests and heart tests show whether your body can handle surgery or certain treatments.

Lab tests on the tissue

Special stains confirm mesothelioma and tell it apart from lung cancer or other cancers that spread to the pleura.

What the stage means

The stage tells how far the cancer has spread. Doctors use the TNM system for pleural mesothelioma. T is how far the tumor has grown along or through the lining. N is whether it has reached lymph nodes. M is whether it has spread to distant parts of the body.

For mesothelioma, the cell type and your overall health often matter as much as the stage. Many people are not able to have surgery, and they are treated with medicines no matter the stage. Your care team will tell you whether surgery is a possibility for you.

Peritoneal mesothelioma is often described by how much of the belly lining is involved, using a score called the PCI. This helps decide whether surgery is possible.

Stage I

Cancer is only in the lining on one side of the chest. It may have grown a little into nearby tissue, but not into lymph nodes.

Stage II

Cancer has grown into nearby structures, like the lung or diaphragm, or has reached lymph nodes on the same side.

Stage III

Cancer has grown deeper into the chest wall or other nearby structures, or has spread to more lymph nodes.

Stage IV

Cancer has spread to the other side of the chest, to distant lymph nodes, or to distant organs.

Resectable or unresectable

Resectable means a surgeon thinks the cancer could be removed. Most mesothelioma is unresectable, meaning surgery is not a good option, and medicines are the main treatment.

Tumor markers and gene tests

Lab tests on your tissue help confirm the diagnosis and show the cell type. Gene tests can give more clues about how the cancer may act and whether it runs in families.

Unlike some lung cancers, mesothelioma rarely has gene changes that can be treated with targeted pills. Immune treatment works whether PD-L1 is high or low. Ask your care team which tests you had.

Cell type

Whether the cancer is epithelioid, sarcomatoid, or biphasic is one of the most important results. It helps guide treatment choices.

BAP1

A gene often changed in mesothelioma cells. Loss of BAP1 on a tissue stain helps confirm the diagnosis.

Inherited BAP1 and other gene changes

A small number of people are born with a gene change that raises the risk of mesothelioma and some other cancers, like eye and skin melanoma and kidney cancer. Genetic testing and counseling are suggested for people diagnosed young, those with peritoneal mesothelioma, those with no known asbestos exposure, or those with a family history of these cancers.

CDKN2A and MTAP

Gene changes that help tell mesothelioma apart from a harmless reaction in the lining. They may also be linked to faster growth.

PD-L1

A protein that can be measured on cancer cells. It is not required to get immune treatment for mesothelioma.

Tumor gene testing (NGS)

A broad test that checks many genes at once. It may help find a clinical trial. Rarely, it finds a change, like an ALK change in some peritoneal cases, that a targeted drug might treat.

Mesothelin

A protein that can be high in the blood in some people. It is not used for diagnosis by itself, but it is being studied, and some trials target it.

Main treatments

Nivolumab with ipilimumab

Two immune checkpoint inhibitors given together by IV. They help your immune system find and attack the cancer. This is a standard first treatment for pleural mesothelioma and is often preferred for sarcomatoid or biphasic types. It is given for up to 2 years.

Chemotherapy with pembrolizumab

A platinum drug (cisplatin or carboplatin) with pemetrexed, plus the immune drug pembrolizumab. The chemotherapy is given for about 6 cycles, and pembrolizumab may continue for up to 2 years. This is another standard first choice, especially for the epithelioid type.

Chemotherapy alone or with bevacizumab

Platinum with pemetrexed is the classic chemotherapy for mesothelioma. Bevacizumab, a drug that blocks blood vessel growth, can be added for some people. This may be used if immune treatment is not a good fit.

Surgery for selected people

A small number of people with early, epithelioid mesothelioma who are healthy enough may have surgery to remove the pleura and visible tumor. This is called pleurectomy and decortication. A larger surgery that removes the whole lung is now rarely done. Recent research showed that surgery does not help many people, so it should be done only after careful review at a center with a lot of mesothelioma experience, usually along with chemotherapy.

Radiation

Used mainly to ease pain from a tumor pressing on the chest wall or nerves. It may also be used after surgery in some cases.

Draining fluid around the lung

Fluid can be drained with a needle to help breathing. To stop it from coming back, doctors may place talc in the chest to seal the space (pleurodesis), or put in a small tube called an indwelling pleural catheter that you or a caregiver drain at home.

Treatment for peritoneal mesothelioma

For some people, surgery to remove all visible tumor in the belly is followed by heated chemotherapy washed through the belly during the same operation (HIPEC). Others get chemotherapy and immune treatment like for pleural mesothelioma.

Treatment if cancer grows

Options include more chemotherapy, such as gemcitabine or vinorelbine, repeating pemetrexed, or an immune drug if you have not had one before.

Clinical trials

Many trials are testing new immune treatments, cell therapies, and drugs that target mesothelin. Because mesothelioma is rare, trials are an important option to ask about at any stage.

Palliative care

Specialists who help with breathing, pain, and other symptoms at any stage, alongside cancer treatment. Good symptom care helps people feel better and stay active.

Common side effects and what helps

Immune side effects

Immune drugs can make the immune system attack healthy organs. This can cause diarrhea, cough or shortness of breath, rash, liver problems, or hormone problems like thyroid or adrenal changes. Most are treatable with steroids if caught early. These can happen during treatment or even months after it ends, so always tell any doctor that you had immune treatment.

Fatigue

Feeling very tired is common from the cancer and from treatment. Short walks, rest, and good sleep habits help. Tell your care team, because thyroid problems or anemia can be treated.

Shortness of breath

Can come from fluid around the lung, the tumor itself, or rarely from lung irritation caused by immune drugs. Tell your care team if it gets worse, because fluid can be drained and other causes treated.

Nausea and loss of appetite

Common with chemotherapy. Take nausea medicine as directed, ideally before you feel sick. Small meals and a dietitian can help you keep your weight up.

Low blood counts and infection

Chemotherapy can lower white cells, red cells, and platelets. Wash your hands often and call right away for a fever.

Vitamins with pemetrexed

You will take folic acid and get vitamin B12 shots to make pemetrexed safer. A steroid may be given to prevent rash. Do not skip these.

Kidney, hearing, and nerve effects from cisplatin

Cisplatin can affect the kidneys, cause ringing in the ears or hearing loss, and cause numbness or tingling. Drinking fluids helps protect your kidneys. Carboplatin may be used instead.

Pain

Chest pain from mesothelioma can be hard to control. A palliative care or pain team can help with medicines, nerve blocks, or radiation.

Catheter care

If you have an indwelling pleural catheter, keep the site clean and dry. Call for redness, pus, fever, or if the catheter stops draining.

Recovery after surgery

Large chest surgery takes weeks to months to recover from. Breathing exercises, walking, and pulmonary rehab help you regain strength.

Living with mesothelioma

Living with mesothelioma often means managing symptoms like breathlessness, pain, and tiredness. Palliative care can be part of your care from the start. It does not mean giving up. It means extra support to help you feel as well as possible. If you have a pleural catheter, you or a caregiver will learn to drain it at home. Draining on a regular schedule can keep breathing easier and help you stay home rather than in the hospital.

Stay as active as you can. Gentle walking, breathing exercises, and pulmonary rehab can help. If you smoke, quitting helps your breathing and your treatment. Keep up with flu, COVID, and pneumonia vaccines.

Write down your work history and any places you may have been exposed to asbestos. Many people with mesothelioma may be able to get compensation, through asbestos trust funds, workers' compensation, or veterans' benefits from the VA. Talk with a trusted lawyer or a social worker. Be careful with ads, and never let anyone pressure you.

Feelings of anger, fear, or sadness are common, especially when the cancer is linked to asbestos exposure at work or at home. Counselors, support groups, and groups like the Mesothelioma Applied Research Foundation can help you and your family.