Malignant mesothelioma of the pleura is a rare and aggressive cancer that affects the thin protective lining surrounding the lungs and the inner chest wall. This lining, known as the pleura, plays a role in smooth lung movement during breathing. When cancerous cells develop within this lining, they can interfere with normal respiratory function. The disease often presents with a long latency period, meaning symptoms may not appear for many decades after initial exposure to its primary cause.
What Pleural Mesothelioma Is and Its Primary Cause
The pleura is a two-layered membrane: visceral pleura covers the lungs, and parietal pleura lines the chest cavity. Malignant pleural mesothelioma originates from mesothelial cells in these linings, which undergo cancerous transformation and spread across pleural surfaces. The main types of pleural mesothelioma cells identified through biopsy include epithelioid, which tends to respond better to treatment, sarcomatoid, which can be more aggressive, and biphasic, a mixture of both cell types.
The main cause of malignant pleural mesothelioma is exposure to asbestos, a fibrous mineral. When asbestos fibers are inhaled, they can become lodged in the pleura. Over a prolonged period, typically 20 to 50 years after exposure, these fibers can induce inflammation and genetic changes in mesothelial cells, leading to cancer. The risk of developing mesothelioma increases with the duration and intensity of asbestos exposure.
Common Symptoms
Individuals with malignant pleural mesothelioma often experience symptoms that develop gradually. Shortness of breath occurs as fluid accumulates in the pleural space (pleural effusion) or as tumors grow and compress the lungs. This fluid buildup can restrict lung expansion, making breathing difficult. Persistent chest pain is a common symptom, often described as a dull ache or tightness, resulting from tumor invasion.
A chronic cough can be present as the disease irritates the airways. Unexplained weight loss and fatigue are systemic symptoms that can accompany many cancers, including mesothelioma. Because these symptoms can be non-specific and mimic other, less serious conditions, early detection of mesothelioma can be challenging.
Diagnosing Pleural Mesothelioma
The diagnostic process for malignant pleural mesothelioma begins with a thorough medical history, focusing on past asbestos exposure, and a physical examination. Initial imaging tests like chest X-rays may reveal pleural thickening, fluid, or masses. CT scans provide detailed chest images, identifying pleural involvement and spread to lymph nodes or organs. PET scans detect metabolically active cancer cells and distant metastases. MRI assesses tumor invasion into the chest wall or diaphragm.
A biopsy is necessary for a definitive diagnosis. Tissue samples are obtained from the pleura for analysis. Thoracoscopy (a small incision procedure) or imaging-guided needle biopsy are commonly used. If significant pleural effusion is present, thoracentesis (draining fluid from the chest) can be performed, and fluid is analyzed for cancerous cells and tumor markers. Pathologists examine samples under a microscope to confirm mesothelioma cells and determine their type, guiding treatment decisions.
Treatment Options
Treatment for malignant pleural mesothelioma is complex and individualized, involving a multimodal approach that combines several therapies. Treatment plans depend on cancer stage, cell type, and patient health. Surgical options are considered for early-stage patients. Procedures like pleurectomy/decortication (P/D) remove the pleural lining and visible tumors from the lung surface. Extrapleural pneumonectomy (EPP) is a more extensive operation, removing the affected lung, pleura, pericardium, and diaphragm on one side.
Chemotherapy is a systemic treatment that uses drugs to destroy cancer cells throughout the body. Common chemotherapy regimens combine pemetrexed with platinum-based drugs like cisplatin or carboplatin. This aims to shrink tumors, slow disease progression, and improve symptoms. Radiation therapy uses high-energy beams to target and destroy localized tumor cells, often used after surgery to eliminate remaining cancer cells or alleviate pain.
Immunotherapy harnesses the body’s immune system to fight cancer cells. Checkpoint inhibitors, such as nivolumab and ipilimumab, are immunotherapy drugs approved for mesothelioma. They block proteins that prevent immune cells from attacking cancer. Supportive care, also known as palliative care, is an important component of treatment, focusing on managing symptoms, improving quality of life, and providing emotional support. This comprehensive approach aims to extend survival and enhance well-being.