Changing trends in US mesothelioma incidence

Our plain-English summary of Changing trends in US mesothelioma incidence, by H. Weill, J.M. Hughes, A.M. Churg (Occupational and Environmental Medicine, 2004).

The study

• Authors: H. Weill, J.M. Hughes, A.M. Churg
• Journal: Occupational and Environmental Medicine
• Published: 2004;61(5):438-41
• Cited by: 104 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Aims: To report the temporal pattern and change in trend of mesothelioma incidence in the United States since 1973.

Methods: The Surveillance, Epidemiology, and End Results (SEER) programme of the National Cancer Institute has since 1973 provided annual age adjusted incidence for mesothelioma in representative cancer registries dispersed throughout the USA. SEER data are analysed to describe the trend of male mesothelioma incidence in the USA.

Results: The US male mesothelioma incidence data indicate that after two decades of increasing incidence, a likely decline has been observed since the early 1990s, when a highly significant change in the upward course occurred.

Conclusions: Increasing male mesothelioma incidence for many years was undoubtedly the result of exposure to asbestos. The high mesothelioma risk was prominently influenced by exposure to amphibole asbestos (crocidolite and amosite), which reached its peak usage in the 1960s and thereafter declined. A differing pattern in some other countries (continuing rise in incidence) may be related to their greater and later amphibole use, particularly crocidolite. The known latency period for the development of this tumour provides biological plausibility for the recent decline in mesothelioma incidence in the USA. This favourable finding is contrary to a widespread fear that asbestos related health effects will show an inevitable increase in coming years, or even decades.

In plain English

This study analysed US cancer registry data from the National Cancer Institute's SEER programme to describe trends in mesothelioma incidence among men from 1973 to 2000. The registries covered about 14% of the US population. The analysis was confined to men, because the authors judged that most mesotheliomas in women are not related to asbestos. Age adjusted rates for men rose from 1973 to the early 1990s and declined after that. A curved (quadratic) trend model fitted to the 1973–2000 data had a highly significant curve term (p less than 0.001), which the authors read as rates having stopped rising and begun to fall. The model placed the peak in 1994. For 1990–2000 alone, rates were consistent with a downturn, but the downward slope was not statistically significant (p = 0.13). The authors concluded that the likely decline most likely reflects exposure controls and reduced use of amphibole asbestos (amosite and crocidolite) since the 1960s. They did not believe diagnostic bias explained the pattern. They noted that differing methods limited comparisons with studies from other countries.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Analysis of national cancer registry incidence data (SEER programme), using age adjusted rates and a quadratic trend model
• Who was studied: Men covered by SEER cancer registries (11 population based and three supplemental registries covering approximately 14% of the US population), 1973–2000
• Exposure: No individual exposures were measured. The authors related male incidence rates to the level and timing of past national asbestos use, particularly use of commercial amphibole fibres (amosite and crocidolite), which they describe as carrying much greater mesothelioma risk than chrysotile asbestos.
• Main results:
  • Age adjusted mesothelioma incidence rates for males increased from 1973 to the early 1990s and declined thereafter
  • In the quadratic model fitted to the 1973–2000 male data, the quadratic term was highly significant (p less than 0.001; the symbol is lost in the scanned text). The authors read this as indicating that rates had ceased to increase and begun to decrease.
  • The model parameters placed the maximum US male mesothelioma incidence rate in 1994
  • Age adjusted male rates for 1990–2000 were consistent with a downturn, but the downward slope was not statistically significant (p = 0.13)
• The authors' conclusion: The authors concluded that the likely declining US mesothelioma incidence in recent years most likely reflects progressive exposure controls and reduced use of amphiboles since the 1960s
• Limitations the authors state:
  • The analysis covers men only. The authors explain that most mesotheliomas in women likely represent background (non-asbestos related) disease.
  • The authors considered diagnostic bias as a possible explanation for changes in incidence, but stated that they did not believe it could account for the effects shown
  • Studies from other countries used varying methods, which limits direct quantitative comparison with the US data

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Mesothelioma, Epidemiology, SEER, Amphibole Asbestos, Crocidolite, Amosite, Amphibole Group, Latency.

Related studies

• Time trend of mesothelioma incidence in the United States and projection of future cases: an update based on SEER data for 1973 through 2005 — B. Price, A. Ware (2009)
• Changing trends in US mesothelioma incidence — M. Greenberg (2005)
• Pleural mesothelioma incidence in Europe: evidence of some deceleration in the increasing trends — F. Montanaro, F. Bray, et al. (2003)
• Response to Letter to the Editor Regarding "Ambient Asbestos Fiber Concentrations and Long-Term Trends in Pleural Mesothelioma Incidence Between Urban and Rural Areas in the United States (1973-2012)" by Finkelstein — K.A. Keeton, M.E. Glynn, et al. (2018)
• Letter Concerning: Glynn ME, Keeton KA, Gaffney SH, Sahmel J. Ambient Asbestos Fiber Concentrations and Long-Term Trends in Pleural Mesothelioma Incidence Between Urban and Rural Areas in the United States (1973-2012). Risk Analysis 2018;38(3):454-471 — M.M. Finkelstein (2018)
• Mesothelioma trends in the United States: an update based on Surveillance, Epidemiology, and End Results Program data for 1973 through 2003 — B. Price, A. Ware (2004)

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