Malignant pleural mesothelioma: an update on investigation, diagnosis and treatment

Malignant pleural mesothelioma is an aggressive malignancy of the pleural surface, predominantly caused by prior asbestos exposure. There is a global epidemic of malignant pleural mesothelioma underway, and incidence rates are predicted to peak in the next few years.

This article summarises the epidemiology and pathogenesis of malignant pleural mesothelioma, before describing some key factors in the patient experience and outlining common symptoms. Diagnostic approaches are reviewed, including imaging techniques and the role of various biomarkers. Treatment options are summarised, including the importance of palliative care and methods of controlling pleural effusions. The evidence for chemotherapy, radiotherapy and surgery is reviewed, both in the palliative setting and in the context of trimodality treatment. An algorithm for managing malignant pleural effusion in malignant pleural mesothelioma patients is presented. Finally new treatment developments and novel therapeutic approaches are summarised.

Malignant pleural mesothelioma (MPM) is an aggressive cancer of the pleural surface. It is associated with previous asbestos exposure, with a latency period of ∼40 years between fibre exposure and disease presentation.

Global incidence of MPM has risen steadily over the past decade, and is predicted to continue to an estimated peak in 2020 [1, 2]. Precise numbers are difficult to determine as the disease is likely to be under reported in areas of low incidence. However, an estimate based on 2008 data suggested an average of 14 200 cases worldwide each year [6]. Total incidence is highest in the USA and UK although per capita, Australia and Italy also rank highly. Unfortunately the ongoing, unregulated use of asbestos in industrial countries such as India, Brazil and Russia means that MPM will continue to represent a significant global health concern even after peak incidence has passed.

Prognosis with MPM is poor and median survival ranges from 8 to 14 months from diagnosis . Women have a more favourable outlook than men, but due to the occupational nature of the disease there is a male predominance of . There are four main histological sub-types; epithelioid, sarcomatoid, biphasic or mixed, and desmoplastic. The sarcomatoid variant is associated with the worst outcomes, with a median survival of just 4 months. In contrast, epithelioid has the most favourable prognosis with a median survival of 13.1 months .

This article will summarise the pathogenesis of MPM, before describing symptoms and exploring elements of the patient’s experience. Diagnostic approaches, including biomarkers and radiological imaging will be outlined. The evidence for chemotherapy, radiotherapy and surgery will be reviewed and new directions for the future will be presented.

The majority of MPM cases are caused by prior exposure to asbestos, often occurring >40 years previously [15]. Asbestos is a naturally occurring silicate mineral that has two different structural forms: the curly, serpentine fibres of chrysotile or “white” asbestos and the sharp, needle-like fibres of amphibole asbestos. The latter can be further divided into crocidolite (blue) asbestos, amosite (brown) asbestos, and anthophyllite, actinolite and tremolite. The risk of developing MPM is related to the type of fibre, as well as to the heaviness and duration of exposure [1].

MPM is classified as an occupational disease since asbestos exposure occurs mainly in the workplace. However, para-occupational exposure can occur, for instance in wives of asbestos workers who launder their clothes [1, 4]. Additionally, asbestos exposure may have occurred outside the workplace or could have happened unbeknownst to the patient.

Other causes of MPM include erionite (a mineral found in the rocks of Turkey), chest wall radiation and simian virus 40. The latter, an oncogenic virus that blocks tumour suppressor genes, may act as a cofactor in the development of MPM, although the evidence for causality is weak

Leave a Reply

Your email address will not be published. Required fields are marked *