Medically Reviewed by Dr. K on 1 April 2021
Table of contents
Mesothelioma is a cancer of the mesothelium, a thin layer that covers the interior of body cavities including the abdomen and chest. Mesothelioma cancer starts in the chest cavity in three out of every four instances. Mesothelioma may also start in the abdominal cavity or in the region around the heart.
Malignant cells from the mesothelium may infiltrate and destroy surrounding tissues regardless of where they come from. Cancer cells may also migrate to other areas of the body, known as metastasis.
The cancer is often advanced by the time mesothelioma is detected. The 5-year survival rate is in the region of 5% to 10%. Respiratory failure or pneumonia are the two frequent causes of death in patients with lung mesothelioma. When a tumour spreads across the diaphragm, a muscle that divides the chest and abdominal cavity, some patients experience a small bowel obstruction. When the tumour invades the pericardium (a thin sac that protects the heart) and the heart itself, a smaller number of individuals suffer from heart problems.
Causes of Mesothelioma
Working with asbestos is the primary cause of mesothelioma. Asbestos is a category of minerals made up of microscopic fibres with thin walls. Asbestos has been extracted and used extensively in the manufacturing, automobile, and other industries due to its resistance to heat, fire, and chemicals, as well as the fact that it does not conduct electricity.
Small asbestos fibres may be inhaled or ingested if they are introduced into the environment during the production phase, creating severe health problems. Up to 75% of mesothelioma patients may be traced back to asbestos contamination at work. There is also evidence that living with asbestos workers places family members and others at risk of contracting mesothelioma and potentially other asbestos-related diseases. This risk may be induced by asbestos dust taken home by the workers on their clothes and hair. People who work around asbestos mines have also been diagnosed with mesothelioma.
However, mesothelioma has been identified in people who have never been exposed to asbestos. Other, less frequent, although potentially serious causes include:
Zeolites. Asbestos is chemically related to these minerals. According to the American Cancer Society, one of these associated minerals, erionite, is present in the soil in certain regions of Turkey. The elevated prevalence of mesothelioma in certain places are assumed to be related to erionite exposure.
Radiation. There have been a few reported cases of mesotheliomas developing during exposure to large doses of radiation to the chest or abdomen, or after injections of thorium dioxide (Thorotrast), a material used by doctors in certain chest X-rays before the 1950s, according to the American Cancer Society.
SV40 virus. According to the American Cancer Society, several laboratory animal studies have shown that infection with the simian virus 40 (SV40) can increase the risk of developing mesothelioma. Between 1955 and 1963, some injectable polio vaccinations became infected with SV40, causing up to 30 million citizens in the United States to be exposed to the virus. The largest human studies to date have found no link between contaminated vaccines and an increased risk of mesothelioma or other cancers in people who received them as children.
Genetics. Certain individuals could be genetically predisposed to mesothelioma. The disease’s prevalence varies among different populations.
Symptoms of Mesothelioma
Symptoms of mesothelioma usually don’t manifest until 20 to 50 years after the original asbestos exposure.
Shortness of breath and chest pain are the most common symptoms of mesothelioma of the lungs. The accumulation of fluid in the pleura induced by mesothelioma can also lead to shortness of breath if it is large enough.
Peritoneal (abdominal) mesothelioma signs include:
- Weight loss
- Swelling and pain in the abdomen
- Blood clotting abnormalities
- Bowel obstruction
Pressure, swallowing difficulties, and swelling of the neck or face are also signs that cancer has spread to other areas of the body.
Since these effects are shared by a number of conditions, experiencing them does not actually imply you have mesothelioma. It’s important to see a doctor to find out what’s causing them.
Medical History and Physical Exam
Since mesothelioma is so rare, it is often misdiagnosed. If you have signs that show you may have mesothelioma, your doctor would usually take a detailed medical history to look for symptoms and possible factors that increase your risk of developing the disease, such as asbestos exposure. The most common factor that increases the risk of mesothelioma is asbestos exposure.
Your doctor will likely inquire into your overall wellbeing and do a physical examination and look for signs of mesothelioma. Fluid in the chest cavity, abdomen, or pericardium (the thin membrane around the heart) are also few of the possibilities.
Your doctor may refer you for mesothelioma testing based on the results of the exam.
Tests for Mesothelioma
There are several types of mesothelioma tests available. There are some of them:
Blood tests. People with mesothelioma have elevated blood levels of three substances: fibulin-3, osteopontin, and soluble mesothelin-related peptides (SMRPs). Since these blood tests cannot confirm a diagnosis of mesothelioma and need further testing before they can be used in a clinical setting, elevated amounts of these compounds increase the risk of the disease.
Fluid and tissue sample tests. If you have a fluid accumulation in the body that could be due to mesothelioma, the doctor will take a measurement of the fluid by inserting a needle into the fluid buildup. The fluid will then be analysed for cancer cells under a microscope. If cancer cells are discovered, further testing will determine whether the cancer is mesothelioma.
Depending on where the fluid is, this test is known by several names:
- Thoracentesis – chest cavity
- Paracentesis – abdomen
- Pericardiocentesis – membrane around the heart
Even if the doctor detects no mesothelioma cells in your fluid, this does not rule out the possibility of mesothelioma. Biopsies of internal tissues are often needed to diagnose mesothelioma.
Biopsies. There are some methods for removing tissue for mesothelioma testing. They are as follows:
- Needle biopsy. A long, hollow needle is inserted into the skin to extract a small piece of a tumour. Imaging tests may be used by the doctor to direct the needle through the tumour. In certain cases, the sample is inadequate to make a diagnosis, necessitating a more invasive process.
- Thoracoscopy, laparoscopy, and mediastinoscopy. A narrow, lighted scope is inserted into a small incision in the skin by the doctor to visualise suspected mesothelioma areas. Small instruments may be inserted by other incisions to remove tissue for examination under a microscope.
The technique varies depending on the region to be examined:
- Thoracoscopy is a procedure that studies the area between the lungs and the chest wall.
- The interior of the abdomen is examined with laparoscopy.
- The middle of the lung, around the heart, is inspected with mediastinoscopy.
- Surgical biopsy. More intrusive techniques may be needed in certain instances to obtain a large enough tissue sample to establish a diagnosis. A doctor may conduct a thoracotomy (chest cavity opening) or laparotomy (abdominal cavity opening) to remove a larger sample of tumour or the whole tumour in this case.
- Endobronchial ultrasound-guided biopsy. This procedure entails inserting a long, thin, flexible tube down the throat to check for tumours in the lungs. The tube often contains an ultrasound, which helps the specialist to accurately locate the tumour and the appropriate location for a biopsy. When a tumour is detected, the specialist will use the tube to remove a tiny sample of it.
Imaging tests. These tests allow your doctor to visualise inside your body without having to make any incisions. The following imaging tests are widely used in the detection of mesothelioma:
- Chest X-ray. An X-ray of the chest can demonstrate irregular thickening or calcium deposits on the lung lining, fluid between the lungs and the chest wall, or changes in the lungs, both of which may signify mesothelioma.
- Computed tomography (CT). The CT scan is a technique that creates accurate photographs of the interior of the body using various X-rays and a monitor. CT scans are often used to screen for symptoms of disease, figure out where the cancer is, to see where it has spread.
- Positron emission tomography (PET). This test involves injecting a compound comprising a radioactive atom into the body and then taking pictures of it. Within the images, cancer cells absorb a lot of the radioactive compound and look brighter than normal tissue. Further tests are then focused on these areas of potential cancer.
- Magnetic resonance imaging (MRI). MRI scans create accurate images of the body using radio waves and powerful magnets. They can help your doctor in locating the tumour by providing detailed images of soft tissues. MRI scans can be especially helpful for mesotheliomas involving the diaphragm (a dome-shaped muscle underneath the lungs).
Prognosis for Mesothelioma
Certain factors influence your mesothelioma prognosis along with your treatment options. The following are some of them:
- The cancer’s stage, or the degree to which it has spread across the body.
- The size of the tumour, whether there are cancer cells in the lymph nodes, and whether the cancer has spread past its original location.
- The mesothelioma tumor’s size
- Is surgery capable of completely removing mesothelioma?
- How much fluid is in the chest or abdomen?
- Your age and overall well-being
- The mesothelioma cell type
- If the cancer has recently been discovered or has already been treated and returned,
Treatments for Mesothelioma
Treatment for mesothelioma is determined by a variety of factors, including those mentioned above. Surgery, radiation, and chemotherapy are the three standard treatments used. When it comes to treating mesothelioma, it’s common to use a mixture of two or all three.
Surgery. The following are the most common surgeries used to treat mesothelioma:
- Wide local excision, which removes the cancer as well as some healthy tissue around it.
- Pleurectomy and decortication are procedures in which the surgeon removes a portion of the lungs’ covering, chest lining, and outer wall.
- Extrapleural pneumonectomy is an operation that includes removing one lung along with a section of the chest lining, the diaphragm, and the lining of the heart sac.
- Pleurodesis is a procedure in which a chemical or medication is used to induce the lung lining to scar and adhere to the lung. The scarring prevents the accumulation of fluid. This is used to manage symptoms and is not intended to be a cure.
Radiation therapy. High-energy X-rays and other forms of radiation are used to destroy or stop mesothelioma cells from developing in this form of cancer treatment. Radiation may be delivered either externally or internally. Remote radiation treatment delivers radiation to the cancer from a device outside the body. Internal radiation involves injecting a toxic agent into the mesothelioma region by needles, seeds, wires, or catheters.
Chemotherapy. This treatment employs medications to halt the development of cancerous mesothelioma cells, either by destroying or keeping them from dividing. Chemotherapy may be taken orally, inserted into a vein or tissue to penetrate the bloodstream and reach mesothelioma cells all over the body, or placed directly into the infected region of the body to target only certain cells. Doctors can recommend more than one chemotherapy medication. Combination chemotherapy is the term for this form of treatment.
Immunotherapy. Certain medications are used to assist the immune system in fighting cancer. The FDA has authorised the combination of nivolumab (Opdivo) and ipilimumab (Yervoy) for unresectable mesothelioma. This is mesothelioma that has spread throughout the body and cannot be treated surgically.
Tumour-treating fields (TTF). Chemotherapy and electric fields of particular wavelengths are used to slow the division of cancer cells in this method of treatment.
Referenced on 1.4.2021
- Brigham and Women’s Hospital International Mesothelioma Program: “Mesothelioma."
- National Cancer Institute: Fact Sheet: “Asbestos Exposure and Cancer Risk," “Mesothelioma: Questions and Answers," “Malignant Mesothelioma Treatment."
- American Cancer Society: “Detailed Guide: Malignant Mesothelioma What Are the Risk Factors for Malignant Mesothelioma?" “Detailed Guide: Malignant Mesothelioma: How Is Malignant Mesothelioma Diagnosed?" “Treatment of Mesothelioma Based on the Extent of the Cancer.”
- UpToDate: “Systemic treatment for unresectable malignant pleural mesothelioma.”