Clinical Importance of Pleural Plaques in Asbestos - Bronchial Carcinoma

In many occupational cohorts, the incidence of bronchial carcinoma is twice or more as high in those with pleural plaques as in those without but with similar asbestos exposure. Persons with plaques also have a risk of developing mesothelioma.

Plaques are in themselves harmless. They may be regarded as an objective sign of previous asbestos inhalation, and it is this exposure that is of possible importance for the future health.

In the literature, it is sometimes recommended that persons with plaques should be followed. However, since they are a fairly common finding, regular investigations of such persons would be costly, and this cost has to be weighed against the potential gains.

Apart from being a sign of asbestos inhalation, plaques are also an indication that sufficient time has elapsed since the first exposure to increase the risk of malignancy from the asbestos exposure.

However, as will be described later, the risk of mesothelioma (and possibly also lung cancer) is related also to the type of asbestos which has caused the plaques: thus, for example, there is a much higher risk to develop mesothelioma if the plaques have been caused by crocidolite exposure than if they had been caused by anthophyllite exposure.

Theoretically, wide-spread calcified plaques might restrict the movements of the chest wall and thereby restrict the lung function.

In fact, persons with pleural plaques have as a group a somewhat lowered lung function, but whether this is due to the effect on the chest wall or an associated slight pulmonary fibrosis is unclear.

Courtesy of The EPA