Projection of future numbers of mesothelioma cases in the US and the increasing prevalence of background cases: an update based on SEER data for 1975 through 2018.

Historically, mesothelioma, which is almost exclusively a cancer of the pleura or peritoneum, has been referred to as a sentinel disease for asbestos exposure meaning that the disease is an epidemiologic marker for asbestos. This description of mesothelioma often has been misinterpreted to mean that the only risk factor for mesothelioma is asbestos. In addition to a few risk factors other than asbestos, in the US, background mesotheliomas, i.e. mesothelioma cases that are a consequence of spontaneous tumor formation, are the most prevalent number of cases after asbestos-associated cases.1 My analysis of SEER data for 1973 through 2005 published in 2009 projected that around 2040 virtually all mesothelioma cases in the US will be background cases. The update here, which is based on the most current SEER data, 1975 through 2018, and the same methods used in 2009 shows that the pattern of mesothelioma incidence is unchanged. Further, in general agreement with the analysis published in 2009, after 2040 virtually all mesothelioma cases, currently estimated to be approximately 1600 per year, will be background cases.