Attributable Fraction of Cancer Related to Occupational Exposure in Italy

Our plain-English summary of Attributable Fraction of Cancer Related to Occupational Exposure in Italy, by G. Collatuzzo, F. Turati, M. Malvezzi, et al (Cancers, 2023).

The study

• Authors: G. Collatuzzo, F. Turati, M. Malvezzi, E. Negri, C. La Vecchia, P. Boffetta
• Journal: Cancers
• Published: 2023;15(8)
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Exposure to occupational carcinogens is an important and avoidable cause of cancer. We aimed to provide an evidence-based estimate of the burden of occupation-related cancers in Italy.

Methods: The attributable fraction (AF) was calculated based on the counterfactual scenario of no occupational exposure to carcinogens. We included exposures classified as IARC group 1 and with reliable evidence of exposure in Italy. Relative risk estimates for selected cancers and prevalences of exposure were derived from large-scale studies. Except for mesothelioma, a 15-20-year latency period between exposure and cancer was considered. The data on cancer incidence in 2020 and mortality in 2017 in Italy were obtained from the Italian Association of Cancer Registries.

Results: The most prevalent exposures were UV radiation (5.8%), diesel exhaust (4.3%), wood dust (2.3%) and silica dust (2.1%). Mesothelioma had the largest AF to occupational carcinogens (86.6%), followed by sinonasal cancer (11.8%) and lung cancer (3.8%). We estimated that 0.9% of cancer cases (N~3500) and 1.6% of cancer deaths (N~2800) were attributable to occupational carcinogens in Italy. Of these, about 60% were attributable to asbestos, 17.5% to diesel exhaust, followed by chromium and silica dust (7% and 5%).

Conclusions: Our estimates provide up-to-date quantification of the low, but persistent, burden of occupational cancers in Italy.

In plain English

This study estimated how much cancer in Italy could be attributed to on-the-job exposure to agents classified by IARC as Group 1 carcinogens, including asbestos. The authors combined relative risks from published meta-analyses and pooled studies with the share of Italians exposed at work around 2001. They then applied the results to national cancer cases in 2020 and deaths in 2017. For mesothelioma, they instead used Italy's National Mesothelioma Registry (ReNaM). Overall, 0.9% of cancer cases and 1.6% of cancer deaths were estimated to be attributable to occupational carcinogens. Mesothelioma had the highest attributable fraction: 86.6% in the main estimate, which also counted cases with an unknown source of exposure, and 69.2% in a narrower estimate. Asbestos was linked to an estimated 1741 deaths and 1869 cases, more than any other agent, and to 0.5% of ovarian cancers. The authors noted several limitations. For cancers other than mesothelioma, exposure was based on job titles. Most relative risks came from studies of men in other countries and were not adjusted for smoking. Many registry mesotheliomas had an undefined exposure. The authors concluded that the burden was low but persistent.

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: Estimate of population attributable fractions (a calculation combining published relative risks with national exposure prevalence and cancer statistics); for mesothelioma, the fraction was taken directly from the Italian National Mesothelioma Registry (ReNaM)
• Who was studied: The population of Italy: cancer incidence in 2020 and cancer mortality in 2017 (from the Italian Association of Cancer Registries), with occupational exposure prevalence from the CAREX Italy study based on 2001 labour force data
• Exposure: IARC Group 1 occupational carcinogens with Italian exposure data. Asbestos (fiber type not specified) was considered for lung cancer, ovarian cancer and mesothelioma, with an exposure prevalence of 0.87%. Other agents included silica dust, diesel exhaust, wood dust, chromium, nickel, arsenic, cadmium, PAH, benzene, formaldehyde, TCE, strong inorganic acid mists and UV radiation.
• Main results:
  • Across all agents, 1.6% of cancer deaths (2017) and 0.9% of cancer cases (2020) in Italy were estimated to be attributable to occupational carcinogens
  • Mesothelioma had the highest attributable fraction to occupational asbestos. It was 86.6% when cases with an unknown source of exposure were included, and 69.2% when only cases classified as occupationally exposed were counted.
  • Under the primary estimate, 1623 mesothelioma deaths and 1720 mesothelioma cases were attributable to occupational exposure. The corresponding figures for lung cancer were 1152 deaths and 1390 cases, from all agents combined.
  • Asbestos accounted for the highest number of attributable cancer deaths (1741) and cases (1869) of any agent. Diesel exhaust followed, with 489 deaths and 621 cases.
  • Asbestos was estimated to account for 0.5% of ovarian cancers, corresponding to 16.2 deaths and 25.1 cases
  • Asbestos was estimated to account for 0.3% of lung cancers, corresponding to 102.7 deaths in 2017 and 123.8 cases in 2020
• The authors' conclusion: The authors concluded that their estimates quantify a low but persistent burden of occupational cancers in Italy. They attributed this mainly to the progressive reduction in exposure to the main occupational carcinogens.
• Limitations the authors state:
  • Except for mesothelioma, exposures were derived from job titles rather than workplace measurements, and the estimates did not account for dose-response
  • ReNaM classified a substantial share of mesotheliomas as having undefined exposure. The authors said this could underestimate the prevalence of occupational asbestos exposure and the related attributable fractions.
  • Because of long latency and higher asbestos exposure in earlier decades, the estimates may undervalue mesothelioma and ovarian cancer cases and deaths. The authors also cited other data suggesting this is unlikely.
  • Most relative risks were not adjusted for smoking and other confounders
  • Relative risks mainly referred to men, except for asbestos and ovarian cancer
  • Relative risks came from studies conducted outside Italy
  • Cases were summed across agents, ignoring that the same workers may have been exposed to several carcinogens
  • The COVID-19 pandemic may have reduced 2020 cancer diagnoses

Topics

Medical terms in this study, explained in our Lexicon: Occupational Exposure, IARC Classification, Relative Risk, Mesothelioma, Latency, Lung Cancer.

Related studies

• Calculation of fractions of lung cancer incidence attributable to occupational exposure to asbestos and combustion products in Stockholm, Sweden — P. Gustavsson, A. Ahlbom, et al. (2003)
• Respiratory Diseases with High Occupational Fraction in Italy: Results from the Italian Hospital Discharge Registry (2010-2021) — P. Ferrante (2024)
• Apportioning causes, targeting populations and predicting risks: population attributable fractions — N. Chatterjee, P. Hartge (2003)
• An estimate of cancers attributable to occupational exposures in France — P. Boffetta, P. Autier, et al. (2010)
• Reducing the underreporting of lung cancer attributable to occupation: outcomes from a hospital-based systematic search in Northern Italy — S. Porru, A. Carta, et al. (2016)
• The future excess fraction of occupational cancer among those exposed to carcinogens at work in Australia in 2012 — R.N. Carey, S.J. Hutchings, et al. (2017)

Browse more research in Cancers, or return to medical research.