Mesothelioma is an aggressive cancer that is primarily, but not always, caused by exposure to asbestos. It has poor prognosis and patients generally survive for only a short time post-diagnosis. Standard mesothelioma treatment methods include chemotherapy and, in some cases, surgery, while a range of innovative treatments are also in the progress of being investigated.
The National Comprehensive Cancer Network, an alliance of leading cancer centres in the USA, only encourages aggressive surgical treatment in patients with mesothelioma affecting epithelioid cells[i]. Consequently, surgery tends to only be performed on patients with epithelioid mesotheliomas.
More disparagingly, in the Mesothelioma Management Guidelines for 2018, the British Thoracic Society has removed surgery from its treatment recommendations for all types of mesothelioma, unless patients take part in a clinical trials, because the expert consensus is that the potential harm of surgery outweighs the benefits.[ii]
However, a new study has suggested that patients with mesothelioma cell types other than epithelioid could benefit from aggressive surgery.
Mesothelioma most commonly affects the lining of the lung (pleural) or abdomen (peritoneal). Mesothelioma cells can be epithelioid or sarcomatoid, as well as biphasic, meaning that both cell types are involved.
Around 70% of mesothelioma cases affect epithelioid cells. Epithelioid mesotheliomas are generally less aggressive and do not spread as quickly as other types of mesothelioma. By contrast, sarcomatoid mesotheliomas, which affect sarcomatoid cells, account for between 7% and 20% of pleural mesothelioma cases and fewer than 4% of peritoneal mesothelioma cases. Sarcomatoid mesotheliomas are the most aggressive, treatment-resistant types of mesothelioma.[iii]
Aggressive surgery options for mesothelioma include extrapleural pneumonectomy and pleurectomy decortication.
In extrapleural pneumonectomy, the diseased portion of the lung, part of the membrane surrounding the heart, part of the diaphragm and part of the membrane which lines the chest are removed. It is usually only performed on patients whose disease has been caught early (before the disease has spread) and on otherwise healthy patients with good function in the remaining lung.[iv] Pleurectomy decortication involves the removal of the pleura and all visible tumour masses, leaving the lung in place.[v]
In the new study, the average survival times of epithelioid, sarcomatoid and biphasic mesothelioma patients, treated with aggressive surgery, were compared with the average survival times of patients who did not undergo aggressive surgery.[vi] The results were, as follows:
- Epithelioid mesothelioma survival: 20.9 months (surgery), versus 14.7 months (no surgery).
- Biphasic mesothelioma survival: 14.5 months (surgery), versus 8.8 months (no surgery).
- Sarcomatoid mesothelioma survival: 11.2 months (surgery), versus 6.5 months (no surgery).
Survival times were therefore longer among surgically operated mesothelioma patients than those who were not operated on, although the difference in survival times was not statistically significant among those with sarcomatoid cell types.
The study findings infer that mesothelioma patients with epithelioid, biphasic and sarcomatoid tumours could all benefit from surgery, in spite of current National Comprehensive Cancer Network and British Thoracic Society guidance.
Dr Charles Simone, co-author of the new study, believes that:
‘Surgery is underutilised in general for all patients [with mesothelioma], but more grossly underutilised in bi-phasic and sarcomatoid patients because the guidelines say don’t even consider it’.
[i] Study: Aggressive Surgery Underutilised with Pleural Mesothelioma. Asbestos.com, 25 September 2018. https://www.asbestos.com/news/2018/09/25/surgery-underutilized-pleural-mesothelioma/ (Accessed 2 October 2018)
[ii] BTS Guideline for the investigation and management of pleural mesothelioma. British Thoracic Society. March 2018 https://www.brit-thoracic.org.uk/standards-of-care/guidelines/bts-guideline-for-the-investigation-and-management-of-pleural-mesothelioma/ (Accessed 2 October 2018)
[iii] Sarcomatoid Mesothelioma. Asbestos.com https://www.asbestos.com/mesothelioma/malignant-sarcomatoid/ (Accessed 2 October 2018)
[iv] Extrapleural Pneumonectomy. USCF department of surgery. https://thoracic.surgery.ucsf.edu/conditions--procedures/extrapleural-pneumonectomy.aspx (Accessed 2 October 2018)
[v] Pleurectomy/Decortication. Asbestos.com. https://www.asbestos.com/treatment/surgery/pleurectomy/ (Accessed 2 October 2018)
[vi] Verma, V. et al. Survival by Histologic Subtype of Malignant Pleural Mesothelioma and the Impact of Surgical Resection on Overall Survival. Clinical Lung Cancer (2018). doi:10.1016/j.cllc.2018.08.007 https://www.sciencedirect.com/science/article/pii/S1525730418302018 (Accessed 2 October 2018)