The risk of lung cancer after cessation of asbestos exposure in construction workers using pleural malignant mesothelioma as a marker of exposure

Our plain-English summary of The risk of lung cancer after cessation of asbestos exposure in construction workers using pleural malignant mesothelioma as a marker of exposure, by B. Järvholm, E. Aström (Journal of Occupational and Environmental Medicine, 2014).

The study

• Authors: B. Järvholm, E. Aström
• Journal: Journal of Occupational and Environmental Medicine
• Published: 2014;56(12):1297-301
• Cited by: 18 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objective: To study the risk of lung cancer in heavily asbestos-exposed workers after the exposure to asbestos has ended.

Methods: Lung cancer was studied in a cohort of 189,896 Swedish construction workers through a linkage with the Swedish Cancer Registry. Asbestos exposure was estimated by the incidence of malignant mesothelioma in the occupational group.

Results: There were in total 2835 cases of lung cancer. Workers with heavy exposure to asbestos had an increased risk of lung cancer (relative risks = 1.74; 95% confidence interval, 1.25 to 2.41) before exposure ended and a similar risk to those with low exposure 20 years after the exposure had ceased (relative risks = 0.94; 95% confidence interval, 0.77 to 1.15).

Conclusions: Workers with heavy exposure to asbestos have a similar risk of lung cancer as persons with low or no exposure 20 years after the exposure has ended.

In plain English

This prospective cohort study linked Swedish construction workers who had attended health examinations to the Swedish Cancer Register through 2011. Sweden banned asbestos by law in 1982, and exposure for almost all Swedish workers ended in the early 1980s. The authors classed 22 occupational groups as heavy, medium or low asbestos exposure by each group's rate of pleural mesothelioma. The lung cancer analysis covered 189,796 men with 2,835 cases and was adjusted for age and smoking. The comparison group was low-exposed workers in 2001 to 2011. In 1972 to 1980, heavy-exposed workers had a relative risk of 1.74 (95% confidence interval 1.25 to 2.41), falling to 0.94 (0.77 to 1.15) in 2001 to 2011. The medium-exposed group showed a similar decline. The authors concluded that 20 years after exposure ended, heavily exposed workers had a lung cancer risk similar to low-exposed workers, while their mesothelioma risk remained higher. They noted that exposure was judged from job title, that smoking habits, taken mainly from the first examination, may have changed, and that fiber types could not be analyzed separately.

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: Prospective cohort study using register linkage, with Poisson regression comparing exposure groups over four time periods
• Who was studied: Men in the Swedish construction industry who attended health examinations. The mesothelioma-based exposure analysis included 249,060 men. The lung cancer analysis included 189,796 men who were examined in 1971 to 1980 and born before 1955, counting only the ages 40 to 74. Follow-up through the cancer register ran to December 31, 2011.
• Exposure: Asbestos exposure in construction work, mainly chrysotile, with some amosite used for spray insulation. Exposure was estimated for each occupational group from its incidence of pleural mesothelioma: more than 10 per 100,000 person-years was classed as heavy, 5.0 to 9.9 as medium, and less than 5.0 as low.
• Main results:
  • There were 2,835 lung cancer cases in the analysis and 406 cases of pleural mesothelioma.
  • For heavy-exposed workers, the age- and smoking-adjusted relative risk of lung cancer fell from 1.74 (95% CI 1.25 to 2.41) in 1972 to 1980 to 0.94 (95% CI 0.77 to 1.15) in 2001 to 2011. The comparison was with low-exposed workers in 2001 to 2011.
  • Lung cancer risk was raised in the heavy and medium exposure groups during the 1970s. From the 1990s it was similar across exposure groups. For medium-exposed workers, the relative risk was 1.41 (1.17 to 1.72) in 1972 to 1980 and 0.92 (0.78 to 1.09) in 2001 to 2011.
  • Risk in the low-exposed group did not change clearly over the decades.
  • Compared with the general population, standardized incidence ratios showed the same declining pattern in the heavy and medium groups. These ratios were not adjusted for smoking.
• The authors' conclusion: The authors concluded that workers with raised lung cancer risk during heavy asbestos exposure had a risk similar to low-exposed workers 20 years after exposure ended, while their mesothelioma risk was still higher. In their view, this indicates that asbestos causes lung cancer and mesothelioma by different mechanisms.
• Limitations the authors state:
  • Exposure was assessed from occupational title, which may cause some nondifferential misclassification and reduce the differences in risk between groups.
  • The exact time each worker stopped being exposed was not known.
  • Smoking habits were taken from the first examination, or from the second or third if first-examination data were missing. They were not updated during follow-up and may have changed over time. If they changed differently between exposure groups, this could cause bias.
  • Other lung carcinogens in construction work, such as diesel exhaust and silica, could introduce bias if exposure to them changed differently over time between groups.
  • Amphiboles cause mesothelioma more readily than chrysotile, so using mesothelioma as the exposure marker may overestimate total exposure in groups such as insulators. Excluding insulators did not substantially change the results.
  • Workers could not be analyzed separately by asbestos type, so no conclusion can be drawn about the time pattern for heavy amphibole exposure.

Topics

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

Medical terms in this study, explained in our Lexicon: Lung Cancer, Asbestos Exposure, Mesothelioma, Cancer Registry, Relative Risk, confidence interval.

Related studies

• The impact of asbestos exposure in Swedish construction workers — B. Järvholm, A. Englund (2014)
• Smoking, occupational exposures, and idiopathic pulmonary fibrosis among Swedish construction workers — M. Andersson, P.D. Blanc, et al. (2021)
• Mesothelioma Risk among Construction Workers According to Job Title: Data from the Italian Mesothelioma Register — L. Vimercati, D. Cavone, et al. (2023)
• Lung cancer risk among workers in the construction industry: results from two case-control studies in Montreal — A. Lacourt, J. Pintos, et al. (2015)
• Occupational exposures and risk of esophageal and gastric cardia cancers among male Swedish construction workers — C. Jansson, A.L. Johansson, et al. (2005)
• Asbestos Exposure and Malignant Mesothelioma in Construction Workers-Epidemiological Remarks by the Italian National Mesothelioma Registry (ReNaM) — A. Binazzi, D. Di Marzio, et al. (2021)

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