Predictions of mortality from pleural mesothelioma in Italy: a model based on asbestos consumption figures supports results from age-period-cohort models

Our plain-English summary of Predictions of mortality from pleural mesothelioma in Italy: a model based on asbestos consumption figures supports results from age-period-cohort models, by A. Marinaccio, F. Montanaro, M. Mastrantonio, et al (International Journal of Cancer, 2005).

The study

• Authors: A. Marinaccio, F. Montanaro, M. Mastrantonio, R. Uccelli, P. Altavista, M. Nesti, A.S. Costantini, G. Gorini
• Journal: International Journal of Cancer
• Published: 2005;115(1):142-7
• Cited by: 108 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Italy was the second main asbestos producer in Europe, after the Soviet Union, until the end of the 1980s, and raw asbestos was imported on a large scale until 1992. The Italian pattern of asbestos consumption lags on average about 10 years behind the United States, Australia, the United Kingdom and the Nordic countries. Measures to reduce exposure were introduced in the mid-1970s in some workplaces. In 1986, limitations were imposed on the use of crocidolite and in 1992 asbestos was definitively banned. We have used primary pleural cancer mortality figures (1970-1999) to predict mortality from mesothelioma among Italian men in the next 30 years by age-cohort-period models and by a model based on asbestos consumption figures. The pleural cancer/mesothelioma ratio and mesothelioma misdiagnosis in the past were taken into account in the analysis. Estimated risks of birth cohorts born after 1945 decrease less quickly in Italy than in other Western countries. The findings predict a peak with about 800 mesothelioma annual deaths in the period 2012-2024. Results estimated using age-period-cohort models were similar to those obtained from the asbestos consumption model.

(c) 2004 Wiley-Liss, Inc.

In plain English

This study used national death certificate data to project future deaths from pleural mesothelioma among men in Italy over the following 30 years. The authors took the 13,303 pleural cancer deaths recorded in Italian men from 1970 to 1999 and counted 73% of them as mesotheliomas, a proportion taken from a Tuscan mesothelioma register. One version of the data also assumed that missed diagnoses fell by 5% per year. They made projections in two ways: with age-period-cohort statistical models, and with a model linking national per-capita consumption of raw asbestos to pleural cancer deaths 40 years later. Annual pleural cancer deaths rose from 227 in 1970 to 753 in 1999. The statistical models predicted peaks of about 730 to 890 mesothelioma deaths per year, mostly in 2015 to 2024. The consumption model predicted 810 to 830 deaths per year in 2012 to 2020. The authors concluded that deaths will likely peak at about 800 a year in 2012 to 2024, and that the two methods gave similar results. They noted that the 73% figure and the misdiagnosis assumption were uncertain. They also could not include the effect of prevention measures in the models.

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: Modelling study projecting future deaths from national mortality data, using age-period-cohort models and a model based on national asbestos consumption
• Who was studied: Italian men aged 25 to 89 who died of pleural cancer from 1970 to 1999 (13,303 deaths, estimated as 9,711 pleural mesothelioma deaths), based on national death certificates; projections ran from 2000 to 2030
• Exposure: National per-capita consumption of raw asbestos (domestic production plus imports minus exports), related to pleural cancer deaths 40 years later. The authors describe Italy as having produced almost exclusively chrysotile, with crocidolite making up 20 to 30% of imports of raw asbestos.
• Main results:
  • Annual pleural cancer deaths among Italian men rose from 227 in 1970 to 753 in 1999. Age-standardized rates went from 1.64 per 100,000 in 1970 to 1974 to 3.22 per 100,000 in 1995 to 1999.
  • Models using the data set corrected only for the 0.73 ratio predicted peak deaths among men of about 890 per year in 2020 to 2024 (model 1), about 780 per year in 2015 to 2024 (model 2) and about 830 per year in 2015 to 2024 (model 3).
  • After the correction for presumed misdiagnoses, models 4 and 6 gave a lower peak of about 730 to 750 deaths per year in 2015 to 2024. The full age-period-cohort model (model 5) gave a peak of about 780 deaths per year in 2015 to 2024.
  • The best-fitting relationship between per-capita asbestos consumption and pleural tumor deaths 40 years later had an R2 of 0.78, which the authors describe as explaining almost 80% of the variability in the data.
  • The asbestos consumption model predicted between 810 and 830 pleural mesothelioma deaths per year among men in 2012 to 2020.
  • Relative risks for the 1945, 1950, 1955 and 1960 birth cohorts, estimated from consumption figures, were 1, 0.97, 0.77 and 0.51. The age-cohort model 1 estimated 1, 0.80, 0.79 and 0.55 for the same cohorts.
• The authors' conclusion: The authors concluded that pleural mesothelioma deaths in Italian men will level off and will likely peak at about 800 per year in 2012 to 2024. They considered this peak delayed compared with the United States, the United Kingdom and the Nordic countries, likely because of Italy's asbestos consumption pattern. They noted that predictions from mortality data were similar to those from the asbestos consumption model.
• Limitations the authors state:
  • The 0.73 ratio of mesothelioma to pleural cancer deaths came from Tuscany in 1994 to 1999, but was assumed to hold for all of Italy over the whole 1970 to 1999 period.
  • The assumed 5% yearly decrease in misdiagnosis still needs to be confirmed.
  • The statistical non-identifiability problem of the full age-period-cohort model was not completely solved.
  • Risks for birth cohorts from 1945 onward could not be estimated precisely because few cases had been observed in them.
  • Men over 75 were included, although mesothelioma diagnosis is problematic in elderly people and misclassification with other causes of death increases in this age group.
  • National consumption is only an indirect, aggregate measure of exposure. Age at first exposure (20) and duration of exposure (20 years) were fixed for all cohorts, although they vary by sector.
  • The effect of prevention measures adopted in Italy since 1970 could not be included quantitatively; the authors say future cases might be fewer and the peak earlier.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Crocidolite, Mesothelioma, Misdiagnosis.

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