Scoping Review of 5 Common Occupational Cancers and Their Related Exposures

Our plain-English summary of Scoping Review of 5 Common Occupational Cancers and Their Related Exposures, by A. Naghibzadeh-Tahami, Y. Khosravi, M. Es'haghi, et al (Medical Journal of the Islamic Republic of Iran, 2022).

The study

• Authors: A. Naghibzadeh-Tahami, Y. Khosravi, M. Es'haghi, A.A. Haghdoost
• Journal: Medical Journal of the Islamic Republic of Iran
• Published: 2022;36:84
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Occupational cancers can be avoided by removing dangerous chemicals from the workplace or limiting occupational exposure. Approximately, 10 major risk factors account for 85% of all occupational cancers. This scoping review study aimed to determine the most important chemical carcinogens related to 5 known occupational cancers. Methods: In this scoping review, we followed Arksey and O'Malley's 5-step framework. Four databases (PubMed, Web of Science, Google Scholar, Scopus) were systematically reviewed for relevant published papers from January 2000 to September 2021. Studies were included in this scoping review, which examined the effect of carcinogenic (definite and probable) chemical exposures on 5 known occupational cancers (lung, bladder, laryngeal, leukemia, and liver). We reported the types of occupational carcinogens, the geographical diversity of studies, extraction of relative risks (RRs), hazard ratios (HRs), or odds ratios (ORs), and identified gaps in the existing literature. Results: The highest number of studies was related to lung cancer (LC) (n = 26), bladder cancer (BC) (n = 11), laryngeal cancer (LaC) (n = 8), leukemia (LeC) (n = 3), and primary liver cancer (PLC) (n = 2), respectively. Most studies were performed in France and Canada (n = 8), Germany (n = 4), Finland (n = 3), Netherlands (n = 2), and Finland (n = 2), respectively. Furthermore, the most common occupational chemical carcinogens associated with the 5 known occupational cancers were asbestos, benzene, crystalline silica, polycyclic aromatic hydrocarbons (PAH), and diesel motor exhausts (DME). Conclusion: Although the attributable risk of occupational cancers in developing countries is much higher, a small proportion of studies were performed in these countries.

© 2022 Iran University of Medical Sciences.

In plain English

This was a scoping review, not a new study of workers. The authors searched PubMed, Web of Science, Google Scholar and Scopus for cohort and case-control studies published from January 2000 to August 2021 on chemical workplace carcinogens and five cancers: lung, bladder, laryngeal, leukemia and primary liver cancer. They kept 45 publications (10 cohort, 35 case-control) and did not rate the quality of each study. Lung cancer had the most studies (26), followed by bladder (11), laryngeal (8), leukemia (3) and liver (2). France and Canada contributed 8 studies each. The authors reported that all but 2 of the studies examining asbestos and lung cancer found a significant association. For laryngeal cancer, 4 studies showed asbestos linked to higher risk, while 1 found no statistically significant relationship. The authors concluded that asbestos, benzene, crystalline silica, polycyclic aromatic hydrocarbons and diesel motor exhaust were among the most common exposures. They also concluded that few studies came from developing countries, where they said the attributable risk is much higher. They noted that studies outside the searched databases may have been missed.

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: Scoping review following Arksey and O'Malley's 5-step framework; individual study quality was not formally assessed
• Who was studied: Published cohort and case-control studies of occupational chemical carcinogens and five cancers (lung, bladder, laryngeal, leukemia, primary liver), found in PubMed, Web of Science, Google Scholar and Scopus, January 2000 to August 2021
• Exposure: Chemical agents classified by IARC as group 1, group 2A or group 2B carcinogens, including asbestos (fiber type not specified), silica, diesel motor exhaust, benzene, PAH, solvents, metals and others; noise, radiation and shift work were excluded
• Main results:
  • 45 publications were retained: 10 cohort studies and 35 case-control studies
  • Number of included studies by cancer: lung 26, bladder 11, laryngeal 8, leukemia 3, primary liver 2
  • Eight included studies each came from France and Canada
  • Among the reviewed studies of asbestos and lung cancer, all except 2 (the Hong Kong and Iran studies) showed a significant association
  • Among the reviewed studies of asbestos and laryngeal cancer, 4 showed increased risk and 1 showed no statistically significant relationship
  • As tabulated from the Netherlands Cohort Study (Offermans 2014; 58279 men aged 55 to 69), ever exposure to asbestos and lung cancer: HR 1.50 (95% CI 1.27 to 1.78)
  • As tabulated from a Canadian bladder cancer case-control study (Latifovic 2020), ever exposure to asbestos: OR 1.32 (95% CI 0.98 to 1.77); exposure 20 or more years ago: OR 2.04 (95% CI 1.25 to 3.34)
  • The most common chemical carcinogens associated with the five cancers were asbestos, benzene, crystalline silica, PAH and diesel motor exhaust
• The authors' conclusion: The authors concluded that, although the attributable risk of occupational cancers is much higher in developing countries, only a small proportion of the studies were done there
• Limitations the authors state:
  • Carcinogenic exposures described only in non-cancer research were not captured, which the authors call the major limitation
  • Research not indexed in the searched databases may have been missed
  • Some included studies did not report all the data needed
  • The quality and risk of bias of individual studies were not formally assessed

Topics

Medical terms in this study, explained in our Lexicon: Occupational Exposure, Carcinogenic, Relative Risk, Hazard Ratio, Odds Ratio, Lung Cancer, Laryngeal Cancer, Crystalline.

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