Predictors of lung cancer among former asbestos-exposed workers

Our plain-English summary of Predictors of lung cancer among former asbestos-exposed workers, by B. Świątkowska, Z. Szubert, W. Sobala, et al (Lung Cancer, 2015).

The study

• Authors: B. Świątkowska, Z. Szubert, W. Sobala, N. Szeszenia-Dąbrowska
• Journal: Lung Cancer
• Published: 2015;89(3):243-8
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: Despite extensive literature concerning the risk of lung cancer incidence among asbestos workers there is still lack of data specifying the association between the level of exposure and the frequency of cancer occurrence. The aim of the analysis was to assess the influence of smoking and selected factors related to occupational exposure on the risk of the incidence of lung cancer among the workers who were exposed to asbestos dust in the past.

Material And Methods: The assessment was performed based on the case-control studies carried out within a cohort including 7,374 former workers of asbestos processing plants, examined over the years 2000-2013. Analysis of the material was based on the calculation of the odds ratio (OR) using conditional logistic regression modeling, adjusted for cigarette smoking, cumulative exposure, branch and time since last exposure.

Results: During the survey period there were 165 cases of lung cancer. Among the individuals who smoked, the relative risk of lung cancer incidence was twice as high in the persons smoking more than 20 pack-years (OR=2.23; 95% CI: 1.45-3.46) than it was in the case of the non-smokers. Analysis revealed that the risk of lung cancer in the group with the highest exposure was two times higher in comparison with the low cumulative asbestos exposure (OR=1.99; 95% CI: 1.22-3.25). The risk continued to increase until 30 years after cessation of asbestos exposure and started to decline many years after the last exposure. Influence of the mentioned above characteristics is particularly visible for tumors located in the lower parts of the lungs.

Conclusion: Our findings confirm the strong evidence that the lung cancer risk is associated with asbestos exposure and it increases along with the increasing exposure. A strategy of smoking cessation among the individuals exposed to asbestos dust would potentially have health promoting effects.

Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

In plain English

The authors studied lung cancer among 7,374 former workers of Polish asbestos-processing plants. Employed between 1943 and 1998, they were examined at least once in 2000-2013 in a health surveillance program. The authors compared 165 lung cancer cases with 825 matched controls from the program. Cumulative exposure to asbestos-containing dust was estimated from past workplace measurements (mg/m3 x years). The study did not identify the fiber types workers were exposed to or give fiber-specific results. Compared with the lowest exposure group (10 or less), the highest group (31 or more) had an odds ratio of 1.99 (95% CI 1.22-3.25). For lower-lobe tumors (39 cases) this odds ratio was 5.64 (95% CI 1.53-20.77). For upper and middle lobes it was not statistically significant. Smoking more than 20 pack-years gave an odds ratio of 2.23 (95% CI 1.45-3.46) compared with non-smokers. Asbestos-cement workers had an odds ratio of 1.50 (95% CI 1.03-2.21) compared with workers of other plants. The authors concluded that risk rises with exposure and that smoking cessation would potentially have health-promoting effects. They noted that participants came forward voluntarily.

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: Case-control study nested within a cohort of former asbestos workers (Amiantus surveillance program). Each lung cancer case was matched with 5 controls by gender, year of birth and vital status, and the data were analysed with conditional logistic regression.
• Who was studied: 7,374 former workers of Polish asbestos-processing plants employed between 1943 and 1998 and examined at least once in 2000-2013. From them, 165 lung cancer cases (130 men, 35 women) and 825 controls (650 men, 175 women).
• Exposure: Asbestos-containing dust in asbestos-processing plants (asbestos-cement plants and other plants). Work posts were grouped as direct production, production service and other (mainly administrative). Exposure was estimated from more than 4,000 gravimetric dust measurements (1956-2000) and expressed as a cumulative exposure index in mg/m3 x years. Smoking was measured in pack-years. The study does not identify the fiber types the workers were exposed to.
• Main results:
  • Workers with the highest cumulative exposure (31 or more mg/m3 x years) had an odds ratio of lung cancer of 1.99 (95% CI 1.22-3.25) compared with the reference group (10 or less), adjusted for smoking, plant type and time since last exposure.
  • For lung cancer in the lower lobe (39 cases), the highest exposure group had an odds ratio of 5.64 (95% CI 1.53-20.77) compared with the low exposure group.
  • For lung cancer in the upper and middle lobes, the highest exposure group's odds ratio was 1.48 (95% CI 0.85-2.58) in the full model (Table 4). This was not statistically significant.
  • Workers who had smoked more than 20 pack-years had an odds ratio of lung cancer of 2.23 (95% CI 1.45-3.46) compared with non-smokers, after adjustment for exposure, plant type and time since last exposure.
  • The interaction between smoking and asbestos dust exposure was not statistically significant (P = 0.65).
  • For lower-lobe lung cancer, smoking more than 20 pack-years gave an odds ratio of 3.22 (95% CI 1.31-7.89) compared with less than 1 pack-year.
  • Workers of asbestos-cement plants had an odds ratio of lung cancer of 1.50 (95% CI 1.03-2.21) compared with workers of other asbestos plants.
  • Workers whose exposure had ended 16-30 years earlier had an odds ratio of 1.71 (95% CI 1.14-2.55) compared with those whose exposure ended 2-15 years earlier.
  • For 31 or more years since exposure ended, the odds ratio was 1.30 (95% CI 0.69-2.49), which was not statistically significant. The authors described the risk as continuing to rise until 30 years after exposure ended and declining many years after.
• The authors' conclusion: The authors concluded that their findings confirm that lung cancer risk is associated with asbestos exposure and increases with increasing exposure. They also concluded that a smoking-cessation strategy among people exposed to asbestos dust would potentially have health-promoting effects.
• Limitations the authors state:
  • Participants came forward for examinations voluntarily, possibly because they wanted an occupational disease diagnosed and compensation, or because they had worse respiratory health.
  • Only about 34% of the roughly 22,000 eligible former workers were examined.
  • Exposure was estimated retrospectively from gravimetric dust measurements rather than fiber counts, because fiber counting began only in the mid-1980s.

Topics

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

Medical terms in this study, explained in our Lexicon: Lung Cancer, Occupational Exposure, Odds Ratio, Cumulative Exposure, Relative Risk, Asbestos Exposure.

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