Exposure to asbestos is the only scientifically verified cause of pleural mesothelioma.
Pleural mesothelioma is the most common type, making up 70-90% of all diagnoses.
The average life expectancy of pleural mesothelioma is 1 year.
Most patients are treated with a combination of surgery, chemotherapy and radiation.
Pleural mesothelioma is a form of mesothelioma that affects the pleural surfaces lining the lungs and inside of the chest wall. Though only about 3,000 new cases of mesothelioma are diagnosed each year, about 70 – 90% of the new diagnoses are pleural mesothelioma. Since it is the most common form of the rare cancer, it is the most studied and has seen promising treatment advancements recently.
Though survival rates have been slightly improving, pleural mesothelioma patients still face a rather poor life expectancy, with only about 40% expected to survive more than a year after diagnosis.
- Cause // Asbestos inhalation
- Location // Lung/chest lining (pleura)
- Common Symptoms // Chest pain
Dyspnea (shortness of breath)
Pleural effusion (fluid buildup)
- Treatment // Surgery
- Prognosis // 6 – 12 months
What Causes Pleural Mesothelioma?
Asbestos exposure is the only definitive cause of pleural mesothelioma. Most often, pleural mesothelioma is caused by inhalation of asbestos fibers. Once inhaled, the durable fibers become lodged in the pleura lining both of the lungs (visceral pleura) and the chest wall (parietal pleura). The asbestos fibers may become trapped in either layer, causing chronic inflammation and cancerous changes that can develop into tumors over time.
Pleural mesothelioma patients often have a sheet-like formation of tumors across the pleura surfaces, and as the tumors grow more advanced, they may invade tissue locally (lung, diaphragm, pericardium, chest wall, mediastinal), as well as spread to draining lymph nodes and sometimes to distant sites.
Diagnosing the Symptoms of Pleural Mesothelioma
Like the other forms of mesothelioma, pleural mesothelioma is difficult to diagnose partially due to indistinct symptoms. At times, this rare cancer has even been confused for the flu, laryngitis, pneumonia, chronic obstructive pulmonary disease (COPD) and other more common lung or respiratory conditions. It has also been misdiagnosed as other lung cancers, like adenocarcinoma.
Common Symptoms of Pleural Mesothelioma
- Chest or lower back pain
- Persistent coughing
- Coughing up blood (hemoptysis)
- Difficulty swallowing (dysphagia)
- Shortness of breath (dyspnea)
- Fluid around the lungs (pleural effusion)
- Hoarseness or difficulty speaking
- Weight Loss
- Blood clots (less common)
Patients experiencing any of these symptoms should talk to their doctor about any possible exposures to asbestos in the past. Even if it happened years ago, no amount of exposure is considered safe, and it can help your doctor test for mesothelioma or other asbestos-related diseases.
With these nonspecific symptoms and the long latency period associated with all forms of mesothelioma, some patients have to wait weeks or even months before receiving a proper pleural mesothelioma diagnosis. Though a diagnosis will generally begin with a variety of imaging tests like CT scans and x-rays to determine the presence of cancer, a biopsy is currently the only method to confirm pleural mesothelioma.
The biopsy will consist of taking samples of pleural tissue for testing. The doctor may also perform a thoracentesis, or a pleural tap, which is a slightly invasive procedure that removes fluid from the pleura for analysis. A pathologist will determine if the cells are malignant, and if pleural mesothelioma is confirmed they will also be able to decipher the cell type.
Pleural Mesothelioma Stages
Unlike the other forms of mesothelioma, pleural mesothelioma has several staging systems that oncologists rely on to determine the progression of the disease. The most widely used and accepted, however, is the TNM Staging System, which stands for Tumor, Nodule, and Metastasis. Doctors will use the system to score an area for each category, which will collectively make up the stage. Roughly, the stage breakdown of pleural mesothelioma is shown in the table below.
Refers to disease which is confined to the primary site, or site of origin. The lymph nodes are free of disease and there are no metastases present. Most often, treatment for stage I mesothelioma consists of surgical resection, or removal, of the disease.
This stage may be further subdivided into IA and IB depth of pleural tumor involvement.
Refers to disease which is confined to one site. While the lymph nodes are still free of disease and there are no metastases present, the tumor extends into the deeper pleural surfaces on the same side as the tumor as well as at least one of the following: the diaphragm or the lung.
Refers to disease which either has spread to lymph nodes on the same side as the tumor; or, a tumor which is extensive and involves the deeper pleural surfaces as well as at least one of the following: chest wall, thoracic fascia, sac around the heart, or mediastinal fat. The tumor is still considered resectable by surgery. There is no metastasis present.
This stage may be further subdivided into IIIA and IIIB depending on contralateral mediastinal lymph node involvement and deeper chest wall invasion, respectively.
Refers to disease in which one of the following occurs: the tumor is too extensive for surgery, there is distant lymph node involvement on the opposite side from the tumor, or there is distant metastasis present.
Less commonly, doctors may also use the Brigham staging system, which focuses on a tumor’s ability to be surgically removed, or the Butchart system, which focuses on the extent of the primary tumor and in general is viewed as more limiting. Regardless of the staging system used, the stage of pleural mesothelioma has a large impact in determining what treatments a patient is eligible for and their prognosis. A stage 1 patient, for instance, will have more treatment options like curative surgery, compared to a stage 4 patient whose malignant mesothelioma has likely spread to other parts of the body or the tumors are too extensive for removal.
Pleural Mesothelioma Prognosis
Like the other types of mesothelioma, pleural mesothelioma patients also face a poor prognosis. Though it is the most common and most researched, doctors still face difficulties in diagnosing and treating the disease. Advancements in treatment and ongoing clinical trials have provided hope in finding new, effective treatments like immunotherapy, which has already shown promise in extending survival for some patients. On average, pleural mesothelioma patients have a life expectancy of about one year, though a number of factors can influence an individual’s prognosis like stage, cell type, and the patient’s age.
According to the data compiled by the American Cancer Society from 2000 – 2013, the 2- and 5- year survival by stage for treated pleural mesothelioma (all subtypes) are:
Malignant Pleural Mesothelioma Survival Rates by Stage
|Stage||2-year Survival||5-year Survival|
The cell type (epithelioid, sarcomatoid and biphasic) can also have a great impact on survival time. Most pleural mesothelioma cases have epithelioid cells, which account for 50-70% of all mesothelioma cases. Epithelioid mesothelioma has the best prognosis amongst subtypes because the cells respond best to treatment and there are more surgical options.
Biphasic cells are the second most common, and consists of a mix of epithelial and sarcomatoid cells. Prognosis for patients showing biphasic cells can vary, dependent on which of the two cell types is more dominant. Sarcomatoid cells are the least common, difficult to diagnose (especially early on), and have a higher chance of spreading. As such, sarcomatoid mesothelioma typically has the worst prognosis. Surgical resection is generally not an option for biphasic and sarcomatoid mesothelioma.
Pleural Mesothelioma Specialists
Finding a mesothelioma specialist is an important aspect of your care, as they have experience evaluating an individual case and treating the disease, which can ultimately help improve your prognosis. Many of these doctors are also involved in research at their cancer centers or heading clinical trials testing the latest, promising treatments.
Pleural Mesothelioma Treatments
Most epithelioid pleural mesothelioma patients are treated with a multimodal plan, which often consists of some combination of surgery, chemotherapy and radiation. There are also many ongoing clinical trials studying the effectiveness of different combination therapies and new treatments. Immunotherapy, in particular, has shown promise for many kinds of cancer, including pleural mesothelioma. Researchers have seen promising results, with some patients extending their survival by months or even years.
For early stage epithelioid pleural mesothelioma patients, there are two curative surgery options that are both considered rather aggressive and invasive. The goal of either option is to remove as many of the tumors and cancer cells as possible to help relieve symptoms and improve life expectancy, but both surgeries face potentially serious risks and complications.
Pleural Mesothelioma Surgeries
- Removal of linings of the lung and chest, and visible tumors in chest wall
- Resection and reconstruction of involved pericardium and diaphragm
- More than 80% of patients report symptom relief after recovery
- Recovery can take anywhere from 3 to 6 weeks on average
- Typically less surgical risk then EPP
- Removal of the entire involved lung and pleural lining, along with resection and reconstruction of the involved pericardium and diaphragm
- Slows disease progression, improves symptoms and overall quality of life
- Recovery is extensive, taking upwards of 10 weeks or more
- May offer best chance of complete disease resection, but significant peri-operative morbidity and mortality risks
- More extensive pre-operative workup to qualify for an EPP
The use and effectiveness of eP/D versus EPP is a very controversial and often debated topic among thoracic surgeons. There are no studies which demonstrate the superiority of one technique over the other, however each patient’s surgical risks must be weighed against the benefits of these procedures.
For patients who aren’t candidates for surgery or as part of a combination therapy, chemotherapy is another tool often used to treat pleural mesothelioma. Though a variety of chemotherapy drug combinations have been used to treat pleural mesothelioma, the standard of care has remained Alimta and Cisplatin for many years. With this treatment, studies have found median survivals of 12 – 16 months. Other chemotherapy combinations, like Avastin in combination with the standard chemotherapy treatment, have had similar results, sometimes even extending survival to 19 months.
Radiation is also often used in combination with surgery or chemotherapy, and in some cases has been applied as a palliative treatment. One recent study explored pleural mesothelioma patients treated with radiation therapy, whether multimodally or individually, over the course of 10 years. The researchers found radiation therapy improved overall survival regardless of how it was implemented in the treatment plan, and should be a tool utilized more regularly to continue improving survival rates.
Clinical trials and research in new therapies and different combinations of even current standard treatments have helped make a lot of progress in improving quality of life and overall survival for mesothelioma patients. In particular, immunotherapy has shown some success in treating pleural mesothelioma, and continues to be an important aspect of research. Certain types of immunotherapy, like the checkpoint inhibitor Keytruda, have enabled some patients to achieve longer survival, and with further study will hopefully become even more effective.
So far, these treatments are only available in clinical trials. Because of the rarity of the disease, it can be difficult for some patients to find or learn about what clinical trials are available and if they are eligible for any of the studies. Working with a mesothelioma specialist can help you learn more about clinical trials and emerging treatments, and determine if any of these options are right for you.
Regardless of what treatment plan might be recommended for your individual case, it’s important to understand all the potential side effects and risks of viable treatments and talk to your family about what’s best for you.