Malignant Mesothelioma

This is a tumour of mesothelial cells which usually occurs in the pleura (80-90% of all cases), but also other sites, including the peritoneum and pericardium.

• It is three times more common in men than women. Often presents between the ages of 40 and 70 years.
• Because of the widespread use of asbestos until the end of the 1970's the incidence of pleural mesothelioma has risen for some decades and is expected to peak between 2010 and 2020.¹
• It is associated with occupational exposure to asbestos but the relationship is complex. 90% report previous exposure to asbestos, but only 20% of patients have pulmonary asbestosis. The latent period between exposure and development of the tumour may be up to 45 years.²

• Chest discomfort, pleuritic pain, dyspnoea, weight loss, fatigue, fever, sweats, finger clubbing, recurrent pleural effusions.
• If the tumour has metastasised there may be lymphadenopathy, hepatomegaly, bone pain/tenderness, abdominal pain/obstruction (peritoneal malignant mesothelioma).
• Examination of the chest often reveals a pleural effusion.

• Chest x-ray: pleural thickening/effusion.
• There is debate as to whether MRI scan of the chest or laparoscopic thoracoscopy is the best method for assessing the extent of the disease.
• Bloody pleural fluid.
• Diagnosis is made on histology, following a pleural biopsy or at post-mortem.

• Stage I: Confined inside the capsule of the parietal pleura: ipsilateral pleura, lung, pericardium, and diaphragm.
• Stage II: All of stage I with intrathoracic (N1 or N2) lymph nodes.
• Stage III: 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: Distant metastases.

• Symptomatic; as cure is only possible with surgery for extremely localised (stage 1) mesothelioma. Traditional treatment modalities (surgery, radiotherapy, and chemotherapy) have evolved slowly, and there has been little improvement in establishing effective treatments.²
• Extrapleural pneumonectomy may lengthen time to recurrence.
• Pleurectomy and decortication may provide palliative relief from pain and pleural effusions (operative mortality 6-30% and less than 2% respectively).
• Studies of chemotherapy have shown poor results but promising results have been achieved with pemetrexed and raltitrexed in combination with cisplatin and other combinations, including cisplatin and gemcitabine. Single-agent therapy with vinorelbine may provide useful palliation with low toxicity.³
• NICE has recommended pemetrexed as a possible treatment for malignant pleural mesothelioma in people:⁴
  • With advanced disease
  • Whose cancer is not suitable for surgical resection
  • Who have a World Health Organization (WHO) performance status of 0 (able to carry out all normal activity without restriction) or 1 (restricted in strenuous activity but able to move around and carry out light work)
  • Patients already taking pemetrexed should continue with treatment until they and their specialist decide that it is the right time to stop treatment
• Radiation therapy can also help pain, but neither DXR or chemotherapy currently improves survival.
• Industrial compensation may be appropriate.

• Difficult to assess because of considerable variation in "time to diagnosis".
• Depends on patient age, staging information, histology and general "performance status" at diagnosis, but is generally very poor (>650 deaths/yr in the UK).
• Median survival is 11 months. It is almost always fatal.