Pleural cancer is cancer that develops in or spreads to the pleura, the thin double-layered membrane that lines your chest cavity and covers your lungs. It comes in two forms: primary pleural cancer, which starts in the pleura itself, and secondary (metastatic) pleural disease, where cancer from another organ spreads to the pleura. The most common primary type is malignant pleural mesothelioma, an aggressive cancer strongly linked to asbestos exposure. The overall five-year survival rate for pleural mesothelioma is about 15%, though outcomes vary significantly depending on how early it’s caught.
Primary vs. Secondary Pleural Cancer
When doctors talk about pleural cancer, they’re usually distinguishing between two very different situations. Primary pleural cancer originates in the mesothelial cells that make up the pleura. Malignant pleural mesothelioma accounts for 70% to 90% of all malignant mesotheliomas and is the most common primary pleural tumor. It’s relatively rare compared to other cancers, but it’s one of the hardest to treat.
Secondary or metastatic pleural disease is far more common. This happens when cancer from the lungs, breast, or another organ spreads to the pleural lining. The treatment approach for metastatic pleural disease focuses on the original cancer, so the management looks quite different from primary mesothelioma. The distinction matters because it changes nearly every decision about treatment and expected outcomes.
How Asbestos Causes Pleural Cancer
Asbestos exposure is the primary cause of pleural mesothelioma. When inhaled, microscopic asbestos fibers work their way into the pleural lining and become permanently lodged there. These fibers damage cells through several pathways at once: they generate reactive oxygen species (unstable molecules that damage DNA), trigger chronic inflammation, and directly injure mesothelial cells. Over time, this combination of ongoing inflammation and DNA damage causes mutations that transform normal cells into cancerous ones.
What makes asbestos particularly dangerous is the long gap between exposure and disease. Mesothelioma typically takes 20 to 50 years to develop after initial exposure, which is why many people diagnosed today were exposed decades ago in workplaces like shipyards, construction sites, or manufacturing plants. Asbestos can also cause non-cancerous pleural thickening and plaques through inflammation alone, without the DNA mutations that lead to cancer.
Other risk factors exist but are far less common. Erionite, a naturally occurring fibrous mineral found in volcanic rock, is associated with increased mesothelioma risk in certain geographic regions. Radiation exposure and inherited mutations in the BAP1 gene also raise a person’s risk, though these account for a small fraction of cases.
Symptoms to Recognize
Pleural cancer symptoms tend to develop gradually and can easily be mistaken for less serious conditions. The most common include chest pain, shortness of breath, painful coughing, and unexplained weight loss. Fatigue is also typical.
One hallmark feature is pleural effusion, a buildup of fluid between the two layers of the pleura. This fluid presses on the nearby lung and progressively makes breathing harder. Some people also notice difficulty swallowing, lumps under the skin on the chest, or pain from pressure on nerves and the spinal cord. Because these symptoms overlap with many lung and heart conditions, the disease is often not suspected until it has progressed.
How It’s Diagnosed
Diagnosing pleural cancer typically starts with imaging. A CT scan is the standard first step, providing detailed views of the pleural lining and any abnormal thickening, masses, or fluid collections. For larger lesions, a PET-CT scan can help identify which areas of the tumor contain viable tissue worth sampling, improving the accuracy of a biopsy.
A tissue biopsy is essential for a definitive diagnosis because imaging alone can’t reliably distinguish between mesothelioma and cancer that has spread to the pleura from elsewhere. For pleural-based lesions, the biopsy can be guided by either ultrasound or CT, with CT preferred for smaller lesions because it allows the doctor to monitor for complications in real time. In some cases, a more involved procedure called video-assisted thoracoscopic surgery is used to obtain larger tissue samples when needle biopsies aren’t conclusive. Pathologists then examine the tissue to confirm the cancer type, its subtype (epithelioid, sarcomatoid, or biphasic), and other characteristics that guide treatment decisions.
Survival Rates by Stage
Pleural mesothelioma survival depends heavily on how far the cancer has spread at diagnosis. Based on data from 2015 to 2021 from the American Cancer Society, the five-year relative survival rates break down as follows:
- Localized (cancer confined to the pleura): 23%
- Regional (spread to nearby structures or lymph nodes): 15%
- Distant (spread to distant organs): 11%
These numbers reflect all patients diagnosed in that time period, and individual outcomes vary based on tumor subtype, overall health, and treatment response. Epithelioid mesothelioma, the most common subtype, generally carries a better prognosis than sarcomatoid or biphasic types.
Treatment Options
Surgery
Two main surgical approaches exist for pleural mesothelioma. Pleurectomy/decortication (P/D) is a lung-sparing operation that removes the diseased pleural lining while leaving the lung intact. Extrapleural pneumonectomy (EPP) is more radical, removing the lung, pleura, pericardium, and diaphragm together as a single block.
Despite being less aggressive, P/D has shown equal or even better survival compared to EPP in most studies, with significantly lower surgical risks. A large meta-analysis found that perioperative mortality was 2.9% for P/D compared to 6.8% for EPP, and complications occurred in 27.9% versus 62.0% of patients. P/D combined with follow-up treatments provided better survival regardless of disease stage or patient fitness. Current guidelines generally recommend P/D as the first option for early-stage disease with favorable tumor characteristics. EPP is typically reserved for cases with deep invasion into lung tissue where complete removal isn’t possible with the lung-sparing approach, or when a patient’s tumor biology makes the more radical surgery the best chance at clearing all visible disease.
Immunotherapy
A combination of two immunotherapy drugs has become the standard first-line treatment for pleural mesothelioma, approved by both the FDA and European regulators. In the landmark clinical trial, this immunotherapy combination improved median overall survival to 18.1 months compared to 14.1 months with traditional chemotherapy. The benefit was especially striking for patients with non-epithelioid subtypes, where median survival more than doubled: 18.1 months versus 8.8 months with chemotherapy alone.
In real-world practice outside of clinical trials, outcomes are somewhat lower, with a median overall survival of 12.6 months and a disease control rate of 62%. About 28% of patients don’t respond to the treatment at all. Serious side effects occur in roughly 30% of patients, reflecting the potency of activating the immune system against cancer.
Chemotherapy
Platinum-based chemotherapy combined with pemetrexed remains an option, particularly for patients who aren’t candidates for immunotherapy. It was the previous standard of care and still plays a role in treatment planning, sometimes used after immunotherapy or alongside surgery.
Managing Fluid Buildup
Pleural effusion is one of the most distressing aspects of pleural cancer, and managing it is a key part of care regardless of what other treatments are being pursued. Two main approaches exist. Pleurodesis involves introducing a substance (often talc) into the pleural space to seal the two layers together and prevent fluid from reaccumulating. Indwelling pleural catheters are small tubes placed in the chest that allow fluid to be drained at home on a regular basis.
Indwelling catheters have become increasingly popular because they reduce the total number of days patients spend in the hospital compared to pleurodesis. They allow people to manage their symptoms at home, maintaining more independence during treatment. Both approaches are effective at relieving breathlessness, and the choice often depends on a patient’s overall treatment plan and personal preferences.