Epidemiology

In 2011, 2540 people were diagnosed and 2310 died of mesothelioma in the United Kingdom (Table 27.1). Three quarters of all mesotheliomas are pleural in origin and the remainder are peritoneal or pericardial. This tumour was originally described by occupational health doctors working in the asbestos factories in the East End of London around the time of the end of the First World War. It would appear, however, that this information was suppressed, and it was not until the 1960s that the association between mesothelioma and asbestos exposure was clearly publicized. The incidence of mesothelioma rose markedly in the last quarter of the 20th century and appears to mirror asbestos exposure rates 20–30 years previously. In the 1970s, after the risk of exposure was recognized, rigorous controls on the handling of asbestos were introduced in the United Kingdom. For this reason the rate of rise of mesothelioma is expected to peak in 2015 and decline thereafter. But this is a global problem and touches countries all over the world from North Korea to South Africa.

Pathogenesis

The development of mesothelioma is generally related to asbestos exposure, but this may not always be the case. The risk of mesothelioma is not related to the amount of exposure. It may not only occur in the asbestos workers but also in family members exposed to the fibres of asbestos brought home in their spouse’s, father’s or mother’s clothes. There are no specific chromosomal changes associated with the development of mesothelioma, but there are a host of abnormalities that may occur, which are entirely non-specific. Different asbestos fibres have different properties and carcinogenicity. The most carcinogenic fibres tend to be the needle-shaped blue (crocidolite) and brown (amosite) asbestos rather than the commoner corkscrew-shaped white asbestos (chrysotile) (Table 27.2).

Presentation

Investigations

The diagnosis of mesothelioma may be suspected from a chest X-ray (Figure 27.1), where a patient may have pleural plaques and an effusion. CT scanning will show the extent of the pleural or peritoneal tumour. The next step in the investigatory process is to carry out a pleural or peritoneal biopsy. Multiple biopsies are frequently needed to make the diagnosis, and video-assisted thoracoscopy (VATS) may be required. A further complication of invasive diagnostic procedures for mesothelioma is the risk of seeding the tumour along the biopsy site resulting in chest wall recurrences. This risk can be reduced by prophylactic radiotherapy to the biopsy track or scar. Recurrent effusions are a dramatic problem for patients, and the intervention of a thoracic surgeon may be required to strip the pleura and provide an effective pleurodesis.

Possibly the most important aspect of the care of patients with mesothelioma is to ensure that the appropriate compensatory mechanisms are put in place. In the United Kingdom, industrial compensation is usually arranged for patients by their union officers and involves an examination of the tumour by a pathology panel. It is enormously important for the patient and his or her family that the clinician signposts this process. In the United Kingdom, two possible benefits are available: compensation from an employer linked to exposure to asbestos and industrial injuries disablement benefit from the Department of Works and Pensions.

Treatment

Prognosis