Pleural cancer mortality in Spain: time-trends and updating of predictions up to 2020

Our plain-English summary of Pleural cancer mortality in Spain: time-trends and updating of predictions up to 2020, by G. López-Abente, M. García-Gómez, A. Menéndez-Navarro, et al (BMC Cancer, 2013).

The study

• Authors: G. López-Abente, M. García-Gómez, A. Menéndez-Navarro, P. Fernández-Navarro, R. Ramis, J. García-Pérez, M. Cervantes, E. Ferreras, M. Jiménez-Muñoz, R. Pastor-Barriuso
• Journal: BMC Cancer
• Published: 2013;13:528
• Type of article: Historical article
• Cited by: 34 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: A total of 2,514,346 metric tons (Mt) of asbestos were imported into Spain from 1906 until the ban on asbestos in 2002. Our objective was to study pleural cancer mortality trends as an indicator of mesothelioma mortality and update mortality predictions for the periods 2011-2015 and 2016-2020 in Spain.

Methods: Log-linear Poisson models were fitted to study the effect of age, period of death and birth cohort (APC) on mortality trends. Change points in cohort- and period-effect curvatures were assessed using segmented regression. Fractional power-link APC models were used to predict mortality until 2020. In addition, an alternative model based on national asbestos consumption figures was also used to perform long-term predictions.

Results: Pleural cancer deaths increased across the study period, rising from 491 in 1976-1980 to 1,249 in 2006-2010. Predictions for the five-year period 2016-2020 indicated a total of 1,319 pleural cancer deaths (264 deaths/year). Forecasts up to 2020 indicated that this increase would continue, though the age-adjusted rates showed a levelling-off in male mortality from 2001 to 2005, corresponding to the lower risk in post-1960 generations. Among women, rates were lower and the mortality trend was also different, indicating that occupational exposure was possibly the single factor having most influence on pleural cancer mortality.

Conclusion: The cancer mortality-related consequences of human exposure to asbestos are set to persist and remain in evidence until the last surviving members of the exposed cohorts have disappeared. It can thus be assumed that occupationally-related deaths due to pleural mesothelioma will continue to occur in Spain until at least 2040.

In plain English

This study looked at deaths recorded as pleural cancer (cancer of the lining around the lungs) in Spain from 1976 to 2010. The authors used these deaths as an indicator of mesothelioma deaths and updated forecasts up to 2020. Because Spain produced almost no asbestos itself, national asbestos imports from 1906 to the 2002 ban served as the measure of exposure. Pleural cancer deaths rose from 491 in 1976–1980 to 1,249 in 2006–2010. Among men, age-adjusted rates levelled off from 2001–2005. Men's risk peaked among those born in 1944–1948 and fell in later generations. Among women, rates declined gradually from the 1980s. The models predicted 1,319 pleural cancer deaths in 2016–2020 (264 per year), an estimated 965 of them mesotheliomas. A second model, based on asbestos imports 36 years earlier, predicted fewer male deaths for 2011–2020 (1,680 versus 1,898). The authors noted that changes in death coding and past under-recognition of the disease could affect the figures. They concluded that occupationally related pleural mesothelioma deaths will continue in Spain until at least 2040.

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: Population-based analysis of national mortality trends using age-period-cohort statistical models, with forecasts to 2020 and a second forecasting model based on national asbestos import figures
• Who was studied: All deaths coded as malignant pleural neoplasm in Spain in national statistics records: 6,037 deaths from 1975 to 2010, of which 3,986 were men and 2,051 were women
• Exposure: Nationwide asbestos exposure, measured as annual per-capita imports of raw asbestos into Spain from 1906 until the 2002 ban; no fiber types are specified. The import-based model used a 36-year lag between imports and deaths.
• Main results:
  • Pleural cancer deaths in Spain (both sexes) rose from 491 in 1976–1980 to 1,249 in 2006–2010
  • The ratio of male to female pleural cancer deaths rose from 1.1 in 1975 to 2.5 in 2010
  • Age-adjusted rates levelled off among men from 2001–2005 and declined gradually among women from the 1980s
  • Among men, the birth-cohort effect was statistically significant (p less than 0.001) but the period effect was not (p = 0.28)
  • Among men, risk of pleural cancer death rose to a peak in those born in 1944–1948 and declined in later generations, most sharply from the 1956 cohort onwards
  • The age-period-cohort models predicted 1,319 pleural cancer deaths in Spain for 2016–2020, or 264 per year
  • From 2006 to 2011, 849 of 1,096 male pleural cancer deaths (77%) were coded as pleural mesothelioma, as were 273 of 436 female deaths (63%). Applying these proportions gave 965 predicted mesothelioma deaths in 2016–2020 (742 men, 223 women; 193 per year).
  • The import-based model fit the observed male deaths with a coefficient of determination of 0.94. For men in 2011–2020 it predicted 1,680 pleural cancer deaths, against 1,898 under the age-period-cohort model.
  • Male pleural cancer deaths in 2006–2010 (897) were about 261 more than an earlier Spanish forecast published in 2008, an underestimate of 41%
• The authors' conclusion: The authors concluded that the different trend in women suggests occupational exposure is possibly the single factor with most influence on pleural cancer mortality. They also concluded that occupationally related pleural mesothelioma deaths will continue to occur in Spain until at least 2040.
• Limitations the authors state:
  • Deaths coded as pleural cancer are only a rough estimate of mesothelioma cases
  • The import-based model gives too much weight to the decline in asbestos imports, and it underestimated the deaths observed in 2011
  • The age-period-cohort forecasts did not take asbestos imports or their decline into account
  • Changes in death-coding practice around 1986–1990 probably affected the observed trend
  • Little attention was paid to asbestos risks in Spain until the 1980s, which may have kept the diagnosis off death certificates
  • Part of the rise in the 1990s could reflect better diagnosis, although the authors considered increased asbestos consumption the more plausible explanation

Topics

Medical terms in this study, explained in our Lexicon: Mesothelioma, Occupational Exposure, Pleural Mesothelioma.

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