Pleural mesothelioma is a rare cancer that develops in the pleura, a thin membrane of cells that line the lungs and chest wall. Pleural mesothelioma is the most common type of the disease, accounting for 80 – 90% of all diagnoses.
Each year, about 2,500 people are diagnosed with pleural mesothelioma. Like all other forms of the disease, asbestos exposure is the only definitive cause. On average, patients survive six to twelve months after diagnosis, though treatments like surgery and chemotherapy can extend life expectancy.
What Is the Prognosis for Pleural Mesothelioma?
As with all types of malignant mesothelioma, prognosis for pleural mesothelioma is poor. For patients who do not receive treatment, the median survival is six months; however, certain types of treatment can improve life expectancy significantly. For instance, recent studies for two types of aggressive surgeries, pleurectomy/decortication and extrapleural pneumonectomy, found median survivals of 36 to 38 months when combined with chemotherapy and radiation.
The biggest factors affecting the prognosis of pleural mesothelioma patients are:
Most pleural mesothelioma patients are diagnosed with the epithelioid cell type, which is the most common. Epithelioid cells typically cluster together and don't metastasize as quickly. They are also the most responsive to treatment. On average, pleural mesothelioma patients with the epithelioid cell type survive 19 months.
The other cell types, sarcomatoid and biphasic, are less common and carry worse prognoses. Sarcomatoid mesothelioma doesn't respond well to treatment and metastasizes aggressively, leaving pleural mesothelioma patients with an average prognosis of 13 months. Patients with biphasic mesothelioma experience more varied life expectancy, depending on whether epithelioid or sarcomatoid cells are more dominant. Studies have found an average prognosis of eight months.
|1 year after diagnosis||73%|
|3 years after diagnosis||23%|
|5 years after diagnosis||12%|
|10 years after diagnosis||4.7%|
According to recent data, within the last decade pleural mesothelioma patients have been surviving longer overall as researchers continue to improve available treatments and diagnostic methods.
What Are the Symptoms of Pleural Mesothelioma?
Anywhere from 20 to 50 years can pass between the time a person is exposed to asbestos and when pleural mesothelioma symptoms begin to appear. After exposure, asbestos fibers will stick to the lining of the lungs, causing inflammation and scarring over time. As the scarring worsens and develops into tumors, patients may begin to notice symptoms.
Once symptoms appear, they often show up first in the chest and respiratory system. One of the most common symptoms is pleural effusion, which is fluid buildup in the pleural cavity. The excess fluid can impact how the lungs and other organs function, and cause other symptoms like chest pain.
Patients may also experience some symptoms that are systemic, like weight loss or fever. As the disease becomes more advanced, new and worsening symptoms may arise.
- Chest pain
- Shortness of breath (dyspnea)
- Fluid in the lungs (pleural effusion)
- Dry cough
Less Common Symptoms
- Weight loss
- Night sweats
Pleural mesothelioma can also be accompanied by a set of other conditions that could display symptoms of their own. These include:
- Pleural plaques – Chalky substance that forms on the lungs due to calcification
- Diffuse pleural thickening (DPT) – Gray, fibrous tissue that fills in pleural spaces
- Asbestosis – Scarring of the lungs (fibrosis)
These conditions may also occur on their own in individuals who do not have pleural mesothelioma.
How Is Pleural Mesothelioma Diagnosed?
As with all types of mesothelioma, diagnosing pleural mesothelioma can be a lengthy process. The first step in a mesothelioma diagnosis is to perform one or more imaging tests (x-ray, CT scans, PET, or MRI) to identify potential tumors.
If a tumor is detected, one or more blood tests may be performed to look for certain biomarkers (high levels of specific substances in the blood), which can help differentiate mesothelioma from other conditions.
Currently, a biopsy is the only way to verify a malignant pleural mesothelioma diagnosis. Tests like a thoracoscopy or thoracentesis may be performed to take a tissue or fluid sample for analysis. For a thoracentesis, a doctor will insert a fine needle to remove fluid buildup in the chest. A thoracoscopy is more invasive. Doctors insert a viewing tube called a thorascope into the chest to inspect the lungs and surrounding area. They can then remove a tissue sample or draw some fluid for analysis. During the biopsy process, a pathologist will study the cells to make a definitive diagnosis, including cell type and how the disease is expected to progress.
Pleural Mesothelioma Stages
As part of the diagnostic process, a mesothelioma specialist will also determine the stage of the disease, or how far it has spread. A patient’s stage is an important indicator of prognosis, and also helps determine what treatment options may be available.
Pleural mesothelioma is currently the only form of the disease with a proper staging system. Mesothelioma doctors may use three different systems to determine the size of the tumors present, as well as if and where the cancer has spread. The most common system used is the Tumor, Node, Metastasis or TNM staging system. Doctors will use the system to score a specific area of the body based on the size of the tumor, if the cancer has spread to the lymph nodes and if the cancer has spread to distant organs.
|Stage 1||22.2 months|
|Stage 2||20 months|
|Stage 3||17.9 months|
|Stage 4||14.9 months|
Stage 1 and stage 2 pleural mesothelioma indicate little to no metastasis, while advanced stages may have distant spreading to lymph nodes and other organs. After the stage is determined, the medical team can develop an effective treatment plan for an individual's case.
Pleural Mesothelioma Specialists
Finding a pleural mesothelioma specialist is an essential aspect of a patient’s care. Since the cancer is rare, many primary care physicians and oncologists have little to no experience with the disease. A specialist will have experience accurately diagnosing mesothelioma and developing personalized treatment plans. Many are also actively involved in research and clinical trials.
Pleural Mesothelioma Treatment
Pleural mesothelioma is typically treated with a multimodal approach, combining standard treatments like surgery, chemotherapy and radiation. The treatment plan will largely depend on the cell type and stage of disease, and the therapies may be approached with a curative or palliative intent based on an individual’s case.
Surgery may be an option for early stage malignant pleural mesothelioma patients. Pleurectomy/decortication, removal of the lung and chest lining, as well as other impacted tissues and organs, is one common surgical option. For some patients, an extrapleural pneumonectomy (EPP), a more aggressive procedure that entails the removal of the affected lung, part of the diaphragm, heart and lung linings, might be a better option for extending survival. Recent clinical trials have found these surgeries can extend life expectancy to three years and longer, especially when applied multimodally.
Doctors often recommend chemotherapy as a follow up treatment for surgery, or as a first-line therapy for patients with more advanced disease. A combination therapy of pemetrexed (Alimta) and cisplatin is most commonly prescribed, though researchers continue to test new combinations. Radiation therapy may also be recommended for select patients to shrink tumors, which may also help relieve symptoms.
When determining their treatment options, patients should also consider the cost of treatment. Reports show one course of treatment with Alimta can cost upwards of $50,000, while surgeries like a pneumonectomy can cost at least $17,000. Understanding treatment costs, along with the risks and benefits of available therapies, is crucial as patients and their loved ones make treatment decisions.
Emerging and Experimental Treatments
Since malignant pleural mesothelioma makes up the majority of mesothelioma cases, most experimental treatment options focus on pleural mesothelioma. Treatments like immunotherapy, gene therapy and photodynamic therapy have shown success in extending life expectancy in various clinical trials.
Studies are also advancing standard treatments to be more effective. An early-phase clinical trial tested a heated chemotherapy wash following pleurectomy/decortication in patients with stage 1 and stage 2 pleural mesothelioma. Patients experienced a median survival of 20.3 months, with 10.7 months of progression-free survival. Though the overall survival was about equal to the typical life expectancy for early stage mesothelioma, the study noted extended survival time without disease progression compared to standard treatments. Studies have found systemic chemotherapy and surgery can lead to local recurrence anywhere from 30 days to several months after being treated. Researchers hope to continue developing and improving these treatments to further improve pleural mesothelioma survival rates.Sources
Ismail-Khan, Rooh, et al. “Malignant Pleural Mesothelioma: A Comprehensive Review.” Cancer Control. 2006 Oct. 13(4): 255-263.
Miles, Susan E. “Clinical consequences of asbestos-related diffuse pleural thickening: A review.” Journal of Occupational Medicine and Toxicology. 2008; 3:20. DOI: 10.1186/1745-6673-3-20
Pairon, Jean-Claude, et al. “Pleural Plaques and the Risk of Pleural Mesothelioma.” Journal of the National Cancer Institute. 20 February 2013, 105(4P): 293-301. DOI: 10.1093/jnci/djs513