Pleural mesothelioma is a rare cancer of the pleura, the lining of the lungs. It is the most common form of cancer caused by asbestos.
Key Points about Pleural Mesothelioma
- Exposure to asbestos is the only scientifically verified cause of pleural mesothelioma.
- Diagnosing pleural mesothelioma can be extremely difficult, since the symptoms may look like those of other diseases.
- While prognosis is generally poor, early detection is the single best way to improve the chances of survival.
- The most common treatment is a combination of surgery, radiation therapy, and chemotherapy
Pleural mesothelioma is a type of cancer that affects the linings of the lungs (the pleura). Caused by exposure to asbestos, pleural mesothelioma is the most common of the three types of mesothelioma. In the U.S., pleural mesothelioma accounts for about 90 percent of the approximately 3,000 diagnosed cases of mesothelioma each year. Approximately 40% of patients survive more than 1 year after a diagnosis. In addition to stage of the cancer at diagnosis, factors like a patient’s age and overall health can affect prognosis.
What are the symptoms of pleural mesothelioma?
Pleural mesothelioma is difficult to diagnose because the symptoms of the disease often resemble common illnesses, including the flu, cold, laryngitis, pneumonia, or whooping cough. The chest pain caused by pleural mesothelioma is often mistaken for heart problems. To further complicate diagnosis, symptoms don’t usually develop until Stage 3 or Stage 4 of the cancer.
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
- Blood clots (less common)
How is pleural mesothelioma diagnosed?
A pleural mesothelioma diagnosis often takes weeks or months due to the long latency period and similar symptoms to more common lung and respiratory diseases. A diagnosis typically begins with a series of image scans, including chest X-rays to detect pleural effusion, CT scans to search for evidence of asbestos exposure, and PET scans to reveal where cancer may have spread. Further testing is required to confirm the presence of cancer, however.
If imaging tests reveal signs of cancer, a biopsy will be required to confirm a diagnosis. A doctor may perform a thoracentesis to sample pleural fluid, which can then be subjected to further tests. Pleural tissue samples will be collected through a biopsy, which is the only way to definitively diagnose pleural mesothelioma.
Once the biopsy is taken, the cells are examined by a pathologist to determine if they are malignant. If pleural mesothelioma is confirmed, the tumor will also be categorized according to its cell type.
How is pleural mesothelioma treated?
Pleural mesothelioma is typically treated with some combination of surgery, radiation therapy, and chemotherapy, with research into innovative multimodal approaches and immunotherapy providing hope for improved outcomes. However, because the disease is typically in an advanced stage when it’s discovered, treatment options are usually very limited.
- Tumors usually too widespread for surgery to be an option
- More often an option with younger, healthier patients
- Two types of surgery
- Pleurectomy/decortication (P/D): tumor and diseased pleura removed
- Extrapleural pneumonectomy (EPP): pleura, affected lung, diaphragm, and pericardium removed
- Target fast-growing cells in an effort to shrink tumors
- Low success rate
- Clinical trials are searching for more effective combinations of drugs
- Kills cancer cells in the lungs and pleura by bombarding with radiation
- Generally not effective on its own
- Usually a palliative option used to manage symptoms of pleural mesothelioma
Most experts agree that a combination of treatments, known as multimodal therapy, is more effective than individual treatments.
As the number of cases of mesothelioma has risen, funding for research into treatments of pleural mesothelioma has increased. Experimental treatments such as immunotherapy offer hope for the future and can give patients options beyond the standard treatments.
- Uses the immune system to fight cancer
- When combined with other treatments, may relieve symptoms and improve survival rates
- Currently only an option in clinical trials
- An increase in mesothelioma cases has led to more funding for research
- Often test new drugs or combinations of therapies
- Offer eligible patients access to experimental treatments, but outcomes are uncertain
What are the causes of pleural mesothelioma?
The pleura is lined with a thin membrane called the mesothelium, which secretes a vital fluid that allows the lungs to expand and contract. Inhaled asbestos fibers become lodged in the pleura, leading to chronic inflammation and scar tissue which may eventually cause tumors.
The surface of the pleura closer to the lung (known as the parietal surface) is often more affected than the surface further away from the lung (visceral surface). The right lung, which is typically larger, often suffers more damage than the smaller left lung. More asbestos tends to settle in the lower lungs than the upper lungs.
Following a diagnosis, patients usually exhibit multiple tumor masses, which grow quickly and can cover the entire lung cavity, causing severe pain and difficulty breathing. In the advanced stages of pleural mesothelioma, the cancer may spread, or metastasize, to other nearby organs, including the heart, abdomen, and lymph nodes.