Fibrous thickening of the lung lining known as pleural plaques are a good indicator of asbestos exposure but they don’t necessarily mean that a person will development mesothelioma.
That is the finding of a risk analysis released by a Princeton, New Jersey-based consulting firm. The firm studied the medical literature on pleural plaques to better understand the relationship between this common asbestos exposure side effect and the development of mesothelioma, the most deadly disease associated with asbestos.
Pleural plaques typically develop two or three decades after asbestos exposure. They can grow on either the outer (parietal) pleura or the inner (visceral) pleura. While they can make breathing uncomfortable as they calcify over time, pleural plaques are not cancerous and have not been shown to become cancerous.
Although pleural plaques have been correlated with mesothelioma in certain types of asbestos, the authors of the new risk analysis say that, in most cases, they are “a marker of exposure rather than an independent risk factor” for mesothelioma development. As evidence, they point to the fact that other fibers besides asbestos have also been known to cause pleural plaques without going on to cause cancer.
A bigger risk factor for mesothelioma, say the researchers, is asbestos itself. Asbestos, a fibrous mineral that occurs naturally in soil and was used for decades in building and insulation materials, is the single biggest cause of mesothelioma worldwide. Despite bans in many developed countries, and asbestos restrictions in others (including the US), tens of thousands of new mesothelioma cases are diagnosed every year.
While they may not be a predictor of disease, pleural plaques are often an indicator of asbestos exposure and, as such, can still be used to indicate which patients should be monitored for asbestos-related diseases such s mesothelioma, lung cancer, and asbestosis.
Maxim, LD et al, “Are pleural plaques an appropriate endpoint for risk analyses?”, June 15, 2015, Inhalation Toxicology, Epub ahead of print