Malignant Pleural Mesothelioma
Malignant mesothelioma is a malignant tumour involving the pleura (lining of lung), induced by asbestos exposure in most cases. There are more than 2,500 new cases diagnosed each year in Britain. The median survival for patients with mesothelioma is thought to be 9-12 months. In the UK National Audit (2016), median survival was 11 months for patients with epithelioid mesothelioma and less than 4 months for patients with sarcomatoid mesothelioma. Recent reports show that with an aggressive approach called multimodality therapy more than a third of patients can survive for five years or more.
Diagnosis of Malignant Pleural Mesothelioma
The diagnosis of of Malignant Pleural Mesothelioma is sometimes obvious in view of a chest CT. However, other pleural cancers can mimic mesothelioma and the diagnosis has to be established by analysing some pleural tissue. In less than 10% of patients, the diagnosis will be made on pleural fluid aspirated through a simple needle. Most patients with this condition now benefit from a Video-Assisted Thoracic Surgery (VATS) pleural biopsy to establish the diagnosis and a VATS talc pleurodesis to prevent the re-accumulation of fluid around the lung. When fluid is absent, an open pleural biopsy is performed by the surgeon under general anaesthetic. When there is a big bulk of tumour, tissue can be obtained through a special biopsy needle under computed tomography (CT) guidance.
Treatment of Malignant Pleural Mesothelioma
The treatment is based on chemotherapy and occasionally radiotherapy for most patients diagnosed with malignant pleural mesothelioma. Chemotherapy involves three-weekly outpatient visits where drugs are injected intravenously over a few hours. Depending on the tolerance and response to treatment, the number of injections (cycles) may vary from two to more than six. The role of immunotherapy agents s currently being investigated in mesothelioma and it is likely that drugs such as pembrolizumab, nivolumab will be approved very soon as phase I and II trials have showed impressive results.
For patients with early stage mesothelioma and a good general condition, multimodality therapy is considered. Multimodality therapy includes chemotherapy, radical surgery aiming at removing all the tumour and radiotherapy. Extrapleural pneumonectomy (EPP) is a major operation consisting in the removal of the tumour together with the all lung and diaphragm. This radical procedure was recently showed to be potentially detrimental. Recent publications have emphasized the importance of preserving the lung. Most mesothelioma surgeons now offer an alternative procedure known as radical pleurectomy / decortication (P/D) consisting in the surgical removal of the involved pleura, but sparing of the lung. This procedure allows re-expansion of the lung and prevents fluid re-accumulation in the chest cavity, improving thereby the quality of life.
We have pioneered the use of intrapleural lavage with povidone-iodine in mesothelioma. This solution is extremely toxic to mesothelioma cells when introduced in the chest cavity and its effect is to cause death of mesothelioma cells. We have shown in our initial 10-year experience that it was safe to lavage the chest cavity with povidone-iodine and suggested that this solution could extend disease-free interval following pleurectomy and decortication.
Depending upon the tumour type, stage and the completeness of removal, up to 45% of patients receiving multimodality therapy can live five years and beyond according to very recent publications.