What is Malignant Mesothelioma?
Malignant mesothelioma is a rare cancer that mostly affects the tissues lining our internal organs, known as mesothelial cells. This cancer is closely linked to asbestos exposure, a harmful substance often found in industrial environments. Mesothelioma can occur at any of those lining layers of our organs such as the abdomen’s lining (peritoneum) or the heart’s lining (pericardium). The most commonly affected area, however, is the lining of the lungs (pleura), leading to malignant pleural mesothelioma. It’s very important to know that the types of asbestos that are strongly related to malignant mesothelioma are amosite and crocidolite asbestos.
What Causes Malignant Mesothelioma?
Malignant pleural mesothelioma, a type of cancer that affects the lining of the lungs, is mostly connected to exposure to a material called asbestos. Some suggest that inhaling asbestos causes this lining to become inflamed repeatedly, disrupts cell division, activates cancer-promoting genes, and starts the production of harmful free radicals. Some reports also link pleural mesothelioma to ionizing radiation, like the kind used to treat Hodgkin lymphoma, or a specific inherited gene change in a gene known as BRCA 1 Associated Protein (BAP1).
However, unlike many other types of lung-related diseases, smoking doesn’t increase the chances of getting malignant pleural mesothelioma. However, when combined with asbestos exposure, smoking does significantly raise the risk of developing other types of lung cancer.
There are certain jobs that are associated with a higher risk of asbestos exposure including:
* Building ships
* Mining
* Making ceramics
* Making cement with asbestos
* Creating car parts, particularly brake linings
* Working at a paper mill
* Doing insulation work
* Repairing railroads
Contrary to many other types of cancer, there’s no evidence that tobacco use, alcohol consumption, or the type of food you eat is involved in causing malignant pleural mesothelioma.
It seems that certain genetic factors or changes may make some people more likely to get this disease. Some studies have shown that one change often seen in patients with this type of cancer is the loss of one copy of their 22nd chromosome. Other commonly seen genetic changes include losses in certain parts of chromosomes 3, 1, 6, and 9.
Risk Factors and Frequency for Malignant Mesothelioma
Malignant pleural mesothelioma is a form of cancer that affects the lining of the lungs. It is less common than lung cancer, with about 2500 new cases in the United States each year compared to more than 160,000 for lung cancer. Most people diagnosed in the U.S. have been previously exposed to asbestos.
The typical patient lives for about a year after diagnosis, as long-term survival is very rare. It especially affects men, commonly after the age of 50, with the average age at diagnosis being 72. Typically, exposure to asbestos happened between 2 to 4 decades prior to diagnosis. However, there have been instances of children getting diagnosed with it, usually without asbestos exposure.
- Asbestos is still widely used in some countries, such as China, which may lead to more instances of malignant pleural mesothelioma.
- In other places like Hong Kong, there’s still high exposure to asbestos, but the rates of the disease are low. The reasons behind these disparities are not fully understood.
Signs and Symptoms of Malignant Mesothelioma
Malignant pleural mesothelioma is a type of cancer that often starts with signs like chest pain and difficulty breathing. Difficulty breathing typically indicates there’s fluid build-up in the space between the lungs and chest wall— a condition known as pleural effusion— which happens in about 90% of patients at first. Some patients might also experience other general symptoms.
- Unintentional weight loss
- Loss of appetite
- Cough
- Fatigue
- Chest wall mass
Testing for Malignant Mesothelioma
If your doctor suspects you might have malignant pleural mesothelioma, a rare and aggressive type of cancer affecting the covering of the lungs (the pleura), they may conduct various tests. This could include a CT scan of your chest with a special dye injected into your veins (intravenous contrast) to improve image clarity, taking a sample of your pleura (thoracoscopic pleural biopsy), and removing and analyzing fluid from your chest (thoracentesis) if any is present.
It’s crucial to distinguish this disease from others that might have similar symptoms or characteristics. These include benign (not cancerous) diseases of the pleura and the spread (metastasis) of other cancers such as lung adenocarcinoma (a type of lung cancer) or chest wall sarcoma (cancer of the chest wall).
On a chest CT scan, malignant pleural mesothelioma might show areas where the pleura is thicker than normal, and in advanced stages, a large invasive mass might be seen. Your doctor may use a PET scan, which shows how your tissues and organs are functioning, to check for the spread of the disease. Moreover, MRI scans and laparoscopy (a minimally invasive surgical procedure) may be performed to check if the disease has spread to the diaphragm (the muscle just below the lungs).
In some cases, a blood protein known as megakaryocyte potentiating factor might be measured. Elevated levels can sometimes serve as a sign, or “biomarker,” of malignant pleural mesothelioma.
If surgery is thought to be a good choice for your treatment, the heart doctor (cardiologist) would first need to confirm that you’re fit enough for surgery. They may conduct a stress test to see how your heart handles workload, and try to enhance your lung function to its best potential.
Treatment Options for Malignant Mesothelioma
The treatment plan for malignant pleural mesothelioma, a type of cancer that affects the lining of the lungs, is mainly based on the stage of the tumor, according to the National Comprehensive Cancer Network Guidelines. Here, staging refers to how far the cancer has spread.
In the case of Stage III-IV malignant pleural mesothelioma, surgery is usually not possible because the disease has advanced too far. In fact, less than a third of all patients with this condition are suitable candidates for definitive surgical removal of the tumor.
It’s recommended that patients with mesothelioma be treated by a diverse group of highly skilled health professionals at a center that handles a considerable number of these cases. This could involve doctors from different disciplines, such as oncology, pulmonology, and surgery to deliver comprehensive and personalized care to these patients.
What else can Malignant Mesothelioma be?
In trying to identify the condition known as malignant pleural mesothelioma, doctors will first need to rule out a set of other conditions that have similar symptoms. These include:
- Non-small cell lung cancer
- Small cell lung cancer
- Drug-induced lung complications
- Benign pleural mass
- Lung infection
- Lung fibrosis
Surgical Treatment of Malignant Mesothelioma
For treatable conditions, there are a couple of surgical options that can be considered. One option is a procedure called Pleurectomy/Decortication (P/D), which may be performed during the early stages of the disease. P/D involves removing part of the covering of the lungs and lining of the chest.
An alternative option is a more intensive surgery called Extrapleural Pneumonectomy (EPP). This involves the removal of the lung, the covering of the heart (pericardium), the diaphragm, and the tissue lining the inside of the chest. This second option is often chosen when the aim is to remove all of the disease, but it can be more dangerous and is associated with a higher chance of death compared to P/D. However, the increased risk could also be tied to the fact that patients with more severe diseases are the ones who typically undergo this procedure.
After EPP, a large dose of radiation therapy is sometimes used to help control the disease locally and prevent it from returning. Some doctors have tried using preventive radiation therapy, but it’s still a topic of debate and no clear benefits have yet been established.
Systemic chemotherapy, which uses drugs to kill cancer cells, can also be used before (neoadjuvant) or after (adjuvant) surgery, and it’s often based on a drug called platinum. Using chemotherapy before surgery may increase the chance of survival, assuming there’s a good response to the treatment. However, its overall effectiveness has yet to be proven. Chemotherapy used after surgery (adjuvant) can be difficult because the drugs used can have harsh side effects, especially after the stress of extensive surgery.
What to expect with Malignant Mesothelioma
Despite advancements in medicine, those diagnosed with malignant pleural mesothelioma, a kind of lung cancer caused mainly by exposure to asbestos, often face a poor prognosis; without treatment, patients typically pass away within 4 to 6 months. However, with appropriate medical intervention, some patients may live for around 15 to 18 months. In very rare cases, patients may even survive for five years after diagnosis.
One significant challenge with this disease is that the tumor often returns, particularly in patients who have undergone surgery.
Although surgery may provide a slight increase in survival time, it can also lead to a range of complications. These can include irregular heart rhythms (arrhythmias), wound infections, blood clots in the veins (deep vein thrombosis), persistent air leakages from the lungs, failure of the respiratory system, postoperative bleeding, and even heart attacks (myocardial infarction).
Certain factors can indicate a potentially worse prognosis. These include a specific type of tumor (nonepithelial histology), a considerable impairment of physical function (poor performance status), being over the age of 75, experiencing difficulty breathing and chest pain at the time of diagnosis, having elevated levels of a certain enzyme in the body (lactate dehydrogenase) and low levels of a protein found in blood (hemoglobin) at diagnosis, and weight loss.
Possible Complications When Diagnosed with Malignant Mesothelioma
Malignant pleural mesothelioma, chemotherapy, and the surgery used to treat it, can all cause complications. This surgery is associated with extremely high levels of serious health risk and potential death. The potential problems could include:
- Heart attack
- Dependence on a breathing machine
- Leakage of air from the lungs
- Failure of the stump left after lung removal
- Failure of multiple organs
- Infection in the surgical wound
- Kidney failure due to cancer drugs, specifically cisplatinum
- Severe decrease in all types of blood cells due to chemotherapy
Recovery from Malignant Mesothelioma
It’s highly recommended for patients to join a rehabilitation program to help them regain their normal functions after undergoing treatment. Eating a balanced and healthy diet is also suggested, as most patients tend to be weak and undernourished. In many cases, the use of oxygen at home might be needed.
