Malignant mesothelioma is a tumour of mesothelial cells which usually occurs in the pleura (80-90% of all cases), but also at other sites, including the peritoneum, pericardium and testes. Malignant pleural mesothelioma rarely metastasises to distant sites but most patients present with locally advanced disease. Patients suffering from asbestos-related mesothelioma may be entitled to compensation.
- Malignant mesothelioma is three times more common in men than in women. It most often presents between the ages of 40 and 70 years.
- The incidence of malignant pleural mesothelioma in the UK is 1.25 per 100,000.
- Exposure to asbestos is a well-established cause, with occupational exposure being documented in 70-80% of those affected.
- It is associated with occupational exposure to asbestos but only 20% of patients also have pulmonary asbestosis.
- The lag period between initial exposure and death varies but one study found a median latency of 32 years, with 96% of cases occurring after at least 20 years. The latent period between exposure and development of the tumour may be up to 45 years.
- Mesothelioma incidence rates have increased almost four-fold since the early 1980s. The number of deaths from mesothelioma in the UK rose from 153 in 1968 to around 2,300 people in 2009. The incidence of mesothelioma is expected to peak at around 2020 and then to decline rapidly.
- Malignant mesothelioma should be considered in any patient with a pleural effusion or pleural thickening, especially if a history of asbestos exposure and chest pain is present.
- Chest pain (typically dull, diffuse, progressive and occasionally pleuritic).
- Breathlessness may be caused by a pleural effusion or circumferential pleural thickening..
- Patients may also present with a palpable chest wall mass.
- Weight loss, fatigue, fever, sweats; finger clubbing is usually caused by underlying asbestosis.
- Pericardial effusion may be caused by local extension in progressive disease. Ascites caused by peritoneal mesothelioma and secondary hydropneumothorax are uncommon but recognised presentations.
- If the tumour has metastasised there may be lymphadenopathy, hepatomegaly, bone pain, bone tenderness, abdominal pain, and gastrointestinal obstruction (peritoneal malignant mesothelioma).
- CXR and CT scan: may show a pleural effusion, lobulated or nodular pleural thickening, a pleural mass, and rib destruction; other features of exposure to asbestos may also be present.
- Pleural fluid: straw coloured or blood stained. Cytological analysis occasionally leads to the diagnosis but a pleural biopsy is usually required.
- Pleural biopsy: ultrasound or CT-guided percutaneous biopsy.
- Mediastinoscopy and video-assisted thoracoscopy may be useful in determining the stage. Thoracoscopy under local anaesthetic (enabling drainage of pleural fluid, pleural biopsy, and pleurodesis) is becoming increasingly available.
See separate article Asbestos-related diseases. Inhalation of asbestos fibres can lead to benign pleural disease (pleural plaques, diffuse pleural thickening, atelectasis), parenchymal lung disease (asbestosis) and malignant chest disease (mesothelioma, lung cancer).
- Stage Ia:
- T1a N0 M0: primary tumour limited to ipsilateral parietal pleura.
- Stage Ib:
- T1b N0 M0: as stage Ia plus focal involvement of visceral pleura.
- Stage II:
- T2 N0 M0: as stage Ia or Ib plus confluent involvement of diaphragm or visceral pleura or involvement of the lung.
- Stage III:
- Any T3 M0: locally advanced tumour.
- Any N1 M0: ipsilateral, bronchopulmonary or hilar lymph node involvement.
- Any N2 M0: subcarinal or ipsilateral mediastinal lymph node involvement.
- Stage IV:
- Any T4: locally advanced technically unresectable tumour.
- Any N3: contralateral mediastinal, internal mammary, and ipsilateral or contralateral supraclavicular lymph node involvement.
- Any M1: 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. Neither radiotherapy nor chemotherapy currently improves survival.
- The role of surgery is controversial but extrapleural pneumonectomy and lung-sparing debulking procedures may be considered.
- Pleurectomy and decortication may provide palliative relief from pain and pleural effusions.
- 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.
- The National Institute for Health and Clinical Excellence (NICE) has recommended pemetrexed as a possible treatment for malignant pleural mesothelioma in people:
- 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).
- If extrapleural pneumonectomy is planned, platinum-based neoadjuvant or adjuvant combination chemotherapy should be considered.
- The exact role of definitive radiotherapy is currently under investigation.
- Prophylactic radiotherapy to the pleural puncture site is often considered in patients who have had large chest wall incisions (during thoracoscopy or insertion of a large-bore chest tube) to reduce the chance of tumour cells seeding along the track to the skin surface.
- Palliative radiotherapy may be used for pain control or the prevention of obstructive symptoms.
- This is difficult to assess because of considerable variation in 'time to diagnosis'.
- It depends on the patient's age, staging information, histology and general 'performance status' at diagnosis, but is generally very poor.
- Median survival is 8-14 months from the time of diagnosis. It is almost always fatal.
Further reading & references
- Khan AN et al, Asbestos-Related Disease Imaging, Medscape, May 2011
- Asbestos Exposure and Cancer Risk, National Cancer Institute (US)
- Malignant pleural mesothelioma: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up; European Society for Medical Oncology (2010)
- DB1 - A guide to Industrial Injuries Disablement Benefits, Department for Work and Pensions (August 2009)
- Tan WW, Mesothelioma, Medscape, Dec 2011
- Currie GP, Watt SJ, Maskell NA; An overview of how asbestos exposure affects the lung. BMJ. 2009 Aug 24;339:b3209. doi: 10.1136/bmj.b3209.
- Pistolesi M, Rusthoven J; Malignant pleural mesothelioma: update, current management, and newer therapeutic strategies. Chest. 2004 Oct;126(4):1318-29.
- Mesothelioma statistics, Cancer Research UK
- Steele JP, Klabatsa A; Chemotherapy options and new advances in malignant pleural mesothelioma. Ann Oncol. 2005 Mar;16(3):345-51. Epub 2005 Jan 27.
- Mesothelioma - pemetrexed disodium, NICE Technology Appraisal (January 2008)
|Original Author: Dr Colin Tidy||Current Version: Dr Colin Tidy||Peer Reviewer: Prof Cathy Jackson|
|Last Checked: 19/07/2012||Document ID: 7051 Version: 6||© EMIS|
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