Predictors of Lung Cancer Risk: An Ecological Study Using Mortality and Environmental Data by Municipalities in Italy

Our plain-English summary of Predictors of Lung Cancer Risk: An Ecological Study Using Mortality and Environmental Data by Municipalities in Italy, by C. Gariazzo, A. Binazzi, M. Alfò, et al (International Journal of Environmental Research and Public Health, 2021).

The study

• Authors: C. Gariazzo, A. Binazzi, M. Alfò, S. Massari, M. Stafoggia, A. Marinaccio
• Journal: International Journal of Environmental Research and Public Health
• Published: 2021;18(4)
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Lung cancer (LC) mortality remains a consistent part of the total deaths occurring worldwide. Its etiology is complex as it involves multifactorial components. This work aims in providing an epidemiological assessment on occupational and environmental factors associated to LC risk by means of an ecological study involving the 8092 Italian municipalities for the period 2006-2015. We consider mortality data from mesothelioma as proxy of asbestos exposure, as well as PM2.5 and radon levels as a proxy of environmental origin. The compensated cases for occupational respiratory diseases, urbanization and deprivation were included as predictors. We used a negative binomial distribution for the response, with analysis stratified by gender. We estimated that asbestos is responsible for about 1.1% (95% CI: 0.8, 1.4) and 0.5% (95% CI: 0.2, 0.8) of LC mortality in males and females, respectively. The corresponding figures are 14.0% (95% CI: 12.5, 15.7) and 16.3% (95% CI: 16.2, 16.3) for PM2.5 exposure, and 3.9% (95% CI: 3.5, 4.2) and 1.6% (95% CI: 1.4, 1.7) for radon exposure. The assessment of determinants contribution to observed LC deaths is crucial for improving awareness of its origin, leading to increase the equity of the welfare system.

In plain English

This ecological study compared areas, not individuals, analyzing 329,101 lung cancer deaths in all 8092 Italian municipalities from 2006 to 2015. Asbestos exposure was not measured for individuals; the authors used each municipality's mesothelioma death rate as a stand-in for past asbestos exposure. They also included fine-particle air pollution (PM2.5), radon, compensated occupational respiratory disease claims, urbanization and deprivation, with COPD and ischemic heart disease deaths as rough stand-ins for smoking. The authors estimated that 1.10% (95% CI 0.82 to 1.39) of male lung cancer deaths (2719 deaths, 2018 to 3419) and 0.53% (0.22 to 0.83) of female deaths (436 deaths, 182 to 689) were attributable to asbestos. PM2.5 above a counterfactual level of 5 µg/m3 accounted for 14.05% (12.47 to 15.68) in men and 16.26% (16.24 to 16.29) in women; radon accounted for 3.92% (3.49 to 4.20) and 1.56% (1.42 to 1.66). Occupational disease claims showed no statistically significant association. The authors cautioned that smoking was not directly measured, that estimates for women rest on few mesothelioma deaths, and that the associations should not be considered causal.

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: Ecological study at municipality level using national mortality, compensation and environmental data, analyzed with a negative binomial regression model, separately for males and females
• Who was studied: All 8092 Italian municipalities, 2006 to 2015; 329,101 lung cancer deaths in total (246,555 in males, 82,546 in females)
• Exposure: Asbestos exposure, measured indirectly through municipal mesothelioma mortality (no fiber types or products specified). Also studied: PM2.5, radon, compensated occupational respiratory disease claims, urbanization and deprivation, with COPD and ischemic heart disease mortality used as proxies for smoking
• Main results:
  • Lung cancer deaths estimated as attributable to asbestos (proxied by mesothelioma deaths): 2719 (95% CI 2018 to 3419) in males and 436 (95% CI 182 to 689) in females. These correspond to 1.10% (95% CI 0.82 to 1.39) of male and 0.53% (95% CI 0.22 to 0.83) of female lung cancer deaths
  • Increase in lung cancer risk per one additional mesothelioma death per 1000 persons: 33.59% in males and 46.74% in females. Table 4 gives the confidence intervals as 21.98 to 46.30 (males) and 17.86 to 82.70 (females)
  • PM2.5: lung cancer risk increased 12.33% (95% CI 10.04 to 14.33) in males and 14.96% (95% CI 11.54 to 18.49) in females per 10 µg/m3. With a counterfactual value of 5 µg/m3, the fraction of lung cancer deaths attributed to PM2.5 was 14.05% (95% CI 12.47 to 15.68) in males and 16.26% (95% CI 16.24 to 16.29) in females
  • Radon: the attributable fraction was 3.92% (95% CI 3.49 to 4.20) in males and about 1.5% in females (1.56% in Table 4, 95% CI 1.42 to 1.66). Compared with the 0 to 50 Bq/m3 reference level, risk was highest at 101 to 150 Bq/m3 in males (17.98%) and above 300 Bq/m3 in females (16.75% in the text). In males, the class above 300 Bq/m3 showed a statistically significant decrease
  • Compensated occupational respiratory disease claims were not statistically significantly associated with lung cancer in either males or females, so no attributable fraction could be estimated
• The authors' conclusion: The authors concluded that the findings confirm a substantial role of environmental and asbestos-related factors in lung cancer risk, and to some extent of occupational ones
• Limitations the authors state:
  • Smoking, diet, obesity and lifestyle were not directly included; individual-level data are impossible in an ecological study
  • The estimated effects should not be considered causal; they may reflect unobserved characteristics of municipalities
  • Mesothelioma counts are low for women, so the asbestos estimate for women is less robust than for men
  • Results must be interpreted considering the different latency periods between asbestos exposure and mesothelioma or lung cancer
  • Radon data were heterogeneous and lacked long-term variation
  • The non-significant result for occupational disease claims was likely due to great variability in compensation procedures

Topics

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

Medical terms in this study, explained in our Lexicon: Lung Cancer, Etiology, Mesothelioma, Asbestos Exposure.

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