• a mesothelioma is associated with exposure to asbestos, especially blue asbestos. A mesothelioma is a tumour of mesothelial cells which generally occurs in the pleura (rarely a mesothelioma may occur in the peritoneum or other organs)
  
  
• exposure may only be brief. There may be a lag-time of 20 to 40 years. Only approximately 20% of patients have pulmonary asbestosis - however about 90% of patients report previous exposure to asbestos
  • when asbestos fibres are inhaled or swallowed, they can cause scarring of the lung tissues, cancer of the bronchial tree (lung cancer) and sometimes cancers in the pleura and peritoneum
    • wide range of occupations, notably shipbuilding, railway engineering and asbestos product manufacture, are associated with an increased risk of mesothelioma
    • family members of people whose work clothes were contaminated with asbestos fibres have also developed mesothelioma
    • condition is significantly more common in men, with a male to female ratio of 5:1
    • people with mesothelioma usually present with the disease between the ages of 60 and 79 years.
      
      
• clinical features:
  • commonly presents with chest pain and dyspnoea - patients often have pleural effusions evident on examination
  • fatigue, profuse sweating, weight loss, anorexia and difficulty in swallowing become common as the disease progresses
  • presentation and diagnosis often occur at an advanced stage and the prognosis for most patients is extremely poor
    
    
• investigations:
  • chest radiography/CT shows a pleural thickening and an associated pleural effusion. These abnormalities are usually unilateral
  • pleural biopsy is required for a certain diagnosis
  • staging
    • stageI: disease confined inside the capsule of the parietal pleura: ipsilateral pleura, lung, pericardium, and diaphragm
    • stage II: as described for stage I with intrathoracic (N1 or N2) lymph nodes
    • stage III: this signifies local extension of disease into the following: chest wall or mediastinum; heart or through the diaphragm, peritoneum; with or without extrathoracic or contralateral (N3) lymph node involvement
    • stage IV: this signifies distant metastases have occurred
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• management
  • this tumour is generally only appropriate for symptomatic treatment. Curative surgical treatment may be possible with stage 1 disease.
    • extrapleural pneumonectomy - this may lengthen time to recurrence
    • palliative pain relief and relief from pleural effusions may be mediated by pleurectomy and decortication
    • chemotherapy
      • NICE have recommended that pemetrexed is recommended as a treatment option for malignant pleural mesothelioma only in people who have a World Health Organization (WHO) performance status of 0 or 1, who are considered to have advanced disease and for whom surgical resection is considered inappropriate
        • however NICE note that there is no standard chemotherapy treatment for malignant mesothelioma. Also NICE notes that there have been no published randomised controlled trials comparing survival and symptom control in patients receiving chemotherapy with those receiving active symptom control (ASC) - treatment that does not include a specific anti-cancer therapy is referred to as ASC
    • radiotherapy may help with pain management
      
      
• prognosis
  • median survival from diagnosis varies in studies, with a range of 9-13 months. Age, tumour histology, tumour stage at diagnosis and performance status have been shown to be independent prognostic factors

Notes (2):

• most commonly used performance status scoring systems include the Karnofsky performance status (KPS) and the World Health Organization (WHO) scales. KPS is a 10-point scale ranging from 0 to 100, with higher scores representing normal day-to-day activity
• WHO system is a five-point scale with lower scores representing normal day-to-day activity
  • in general, WHO scores of 0 and 1 are considered equivalent to KPS scores of 70-100

Reference:

1. Lancet (1995), 345,1233-4.
2. NICE (January 2008).Pemetrexed for the treatment of malignant pleural mesothelioma