Diseases of the Pleura and Mediastinum
Summary of Key Points
Malignant Pleural Mesothelioma (MPM)
Epidemiology
• MPM is a rare disease with 2,000 to 3,000 cases annually in the United States.
• It is associated with prior occupational asbestos exposure, but some patients without known asbestos exposure will develop MPM.
• Four subtypes exist: epithelioid, sarcomatous, biphasic epithelial (also referred to as mixed), and desmoplastic.
• Epithelioid is the most common and may be associated with a better prognosis.
Differential Diagnosis
• Diagnosis must be differentiated from metastatic adenocarcinoma or non–small cell lung cancer with adenocarcinoma histology. No single test is diagnostic of MPM, and it frequently requires a panel of immunohistochemistry markers to confirm the diagnosis.
• Cytologic analysis of pleural fluid is not reliable to exclude MPM, and many times a thoracoscopic biopsy may be required for definitive diagnosis. Evidence of invasion into subpleural adipose tissue is the most reliable indicator of malignancy.
Staging
• Computed tomographic (CT) scan is the initial staging procedure.
• Positron emission tomography (PET) or PET-CT scan has the ability to detect extrathoracic disease.
• Cervical mediastinoscopy may be useful for detecting mediastinal involvement.
• Peritoneal lavage or laparoscopy is indicated if peritoneal involvement is suspected.
Primary Therapy
• For patients with operable disease without significant co-morbidities, surgical options include extrapleural pneumonectomy or pleurectomy and decortication.
• Single-institution and phase II trials have demonstrated the feasibility of multimodality therapy.
• The benefit of post- or preoperative radiation and chemotherapy is undefined.
• For patients with unresectable disease or metastatic disease, without significant treatment co-morbidities, and preserved performance status, treatment with a platinum agent (cisplatin or carboplatin) and antifolate (pemetrexed or raltitrexed) is the standard therapy.
• A variety of agents have shown activity in the second-line setting.
