Pleural mesothelioma is a cancer that forms in the thin membrane surrounding the lungs, called the pleura. It is almost always caused by asbestos exposure, often decades earlier, and carries a five-year survival rate of about 15% across all stages. It is the most common form of mesothelioma, accounting for the large majority of cases.
Where It Starts: The Pleura
Your lungs are wrapped in a two-layered membrane called the pleura. The outer layer (parietal pleura) lines the inside of your chest wall, while the inner layer (visceral pleura) sits directly on the surface of your lungs. A thin film of fluid between these layers lets them glide smoothly against each other as you breathe. Pleural mesothelioma develops when the cells lining these membranes begin growing out of control, eventually forming tumors that thicken and stiffen the pleura.
One detail that matters for symptoms: the outer layer is packed with pain-sensing nerves, while the inner layer has almost none. This is why chest pain often becomes severe as the cancer grows into the chest wall.
How Asbestos Causes the Disease
When asbestos fibers are inhaled, they’re small enough to travel deep into the lungs and eventually reach the pleura. Researchers believe the natural negative pressure inside the pleural cavity helps pull fibers toward the outer membrane over time. Once lodged there, the fibers cause damage through several overlapping processes.
Immune cells try to destroy the fibers by engulfing them, but asbestos is essentially indigestible. The frustrated immune cells release large amounts of unstable molecules called free radicals, which damage the DNA of nearby cells. Iron on the surface of the asbestos fibers accelerates this process. Beyond this chemical damage, asbestos fibers can physically enter cells and reach the nucleus, where they tangle with chromosomes during cell division and cause mutations directly. A third mechanism involves asbestos fibers acting like magnets for cancer-promoting chemicals in the body, concentrating them in one area and amplifying the damage.
The time between first asbestos exposure and a mesothelioma diagnosis is strikingly long. The average latency period is about 34 years, with a range that spans from as few as 8 years to as many as 84 years. This means people diagnosed today were typically exposed to asbestos in the 1980s or 1990s, and sometimes much earlier.
Symptoms and How They Progress
Early symptoms are easy to dismiss or attribute to something else. The most common initial signs include shortness of breath, chest pain, a persistent painful cough, unexplained weight loss, and fatigue. Some people notice unusual lumps under the skin on their chest.
As the cancer advances and spreads within the chest cavity, it presses on surrounding structures and causes more severe problems. Difficulty swallowing develops when tumors press on the esophagus. Nerve compression can cause pain radiating into the shoulder or down the arm. One of the most common complications is pleural effusion, a buildup of fluid between the two pleural layers that compresses the lung and makes breathing progressively harder. Many patients first seek medical attention because of this fluid buildup rather than the cancer itself.
How It’s Diagnosed
Diagnosis typically begins with a contrast-enhanced CT scan of the chest, optimized to show the pleural surfaces in detail. If doctors need to assess whether the cancer has invaded the chest wall or diaphragm, MRI provides better soft-tissue contrast. PET-CT scans are used when there’s concern the cancer may have spread to distant parts of the body.
Imaging alone cannot confirm mesothelioma. A tissue biopsy is required. If fluid has collected around the lung, doctors will first test a sample of that fluid, but fluid analysis alone is not reliable enough for a definitive diagnosis. The preferred approach is thoracoscopy, a procedure where a small camera is inserted into the chest through a tiny incision to directly view the pleura and take tissue samples. When thoracoscopy isn’t feasible, a needle biopsy guided by imaging can be used to sample a suspicious area of pleura with high accuracy and low risk.
Once tissue is obtained, pathologists use a panel of specialized staining techniques to distinguish mesothelioma from other cancers that can look similar under a microscope, particularly lung adenocarcinoma. Getting this distinction right is critical because treatment differs significantly.
Stages of the Disease
Pleural mesothelioma is staged from I to IV based on how far the tumor has spread. Stage I means the cancer is confined to the pleura on one side of the chest with no lymph node involvement. Stage II involves spread to nearby lymph nodes. Stage III indicates more extensive lymph node involvement or deeper invasion into chest structures. Stage IV means the tumor has grown into structures that can’t be surgically removed, has reached lymph nodes on the opposite side of the chest, or has spread to distant organs.
Five-year survival rates reflect this progression clearly. For localized disease, about 23% of patients survive five years. Regional spread drops that to 15%, and distant spread to 11%. These numbers come from patients diagnosed between 2015 and 2021, so they don’t fully reflect the newest treatment options.
Surgery Options
Two major surgical approaches exist for pleural mesothelioma, and they differ dramatically in scope. Pleurectomy with decortication (P/D) removes the diseased pleural lining and all visible tumor while leaving the lung intact. Extrapleural pneumonectomy (EPP) is far more radical: it removes the entire lung on the affected side along with the pleura, the diaphragm, and part of the membrane around the heart.
EPP historically carried mortality rates above 10%, though experienced centers have brought this below 5%. P/D carries a lower surgical death rate and is generally better tolerated, especially in older patients or those with limited lung function. The trade-off is that P/D tends to have higher rates of the cancer returning in the same area, while EPP patients more often see recurrence in the opposite lung or abdomen. Despite these different patterns, large studies comparing the two approaches have found no significant difference in long-term survival.
The most common complication after P/D is a prolonged air leak from the lung surface where tumor was peeled away. After EPP, the major risks include dangerous heart rhythm problems, blood clots in the lungs, and infection from a leaking airway stump. The trend in recent years has moved toward lung-sparing P/D for most patients.
Chemotherapy and Immunotherapy
For patients whose cancer cannot be surgically removed, or as an addition to surgery, systemic treatment is the standard approach. The backbone of mesothelioma chemotherapy has long been a combination of two drugs: one that disrupts how cancer cells build DNA, paired with a platinum-based drug that damages cancer cell DNA directly.
In September 2024, the FDA approved the addition of an immunotherapy drug (pembrolizumab) to this chemotherapy combination as a first-line treatment for advanced pleural mesothelioma. This drug works by blocking a protein that cancer cells use to hide from the immune system, essentially removing the brakes so the body’s own defenses can attack the tumor. Treatment continues on a regular schedule until the cancer progresses or side effects become unmanageable, up to a maximum of two years.
Managing Fluid Buildup
Pleural effusion is one of the most debilitating aspects of living with pleural mesothelioma, and managing it effectively can significantly improve quality of life. The two main approaches are pleurodesis and indwelling pleural catheters.
Pleurodesis aims to permanently seal the two layers of the pleura together so fluid can no longer accumulate between them. The most common method uses sterile talc, which triggers an inflammatory reaction that fuses the membranes. Talc can be applied during a surgical procedure under direct visualization or mixed into a slurry and delivered through a chest tube at the bedside. Studies suggest that using a larger chest tube improves success rates with the slurry method. Pleurodesis only works if the lung can fully expand to meet the chest wall. In mesothelioma, the lung is often trapped by tumor and can’t re-expand, making pleurodesis ineffective.
When that happens, an indwelling pleural catheter offers an alternative. This is a small, flexible silicone tube tunneled under the skin into the pleural space, with a one-way valve at the external end. Patients or caregivers can drain fluid at home, typically daily, without needing to visit a clinic. The catheter stays in place long-term and, in some cases, the ongoing drainage triggers enough inflammation to seal the pleural space on its own. Doctors can also instill talc through the catheter in an outpatient setting to speed this process, an approach shown in randomized trials to improve pleurodesis rates without increasing side effects.