Occupational and Environmental Asbestos Exposure and Survival of Patients with Asbestos-Related Cancer: A Follow-Up Study on Patients with Malignant Mesothelioma and Asbestos-Related Lung Cancer in Korea

Our plain-English summary of Occupational and Environmental Asbestos Exposure and Survival of Patients with Asbestos-Related Cancer: A Follow-Up Study on Patients with Malignant Mesothelioma and Asbestos-Related Lung Cancer in Korea, by M.S. Kang, W.R. Chae, Y.J. Lee, et al (Toxics, 2023).

The study

• Authors: M.S. Kang, W.R. Chae, Y.J. Lee, K.W. Moon
• Journal: Toxics
• Published: 2023;12(1)
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Malignant mesothelioma and asbestos-related lung cancer are typically associated with a poor prognosis. However, it has been observed that some patients with these cancers survive significantly longer than the average survival period. While many preliminary studies have investigated factors influencing patient survival, the specific impact of asbestos exposure has not been thoroughly explored. We followed up with 546 patients with malignant mesothelioma and 902 patients with asbestos-related lung cancer, all identified as asbestos victims between 2009 and 2021. In both malignant mesothelioma and asbestos-related lung cancer, patients with occupational asbestos exposure exhibited not only shorter median survival times but also lower 3- and 5-year survival rates compared to those with environmental exposure. Additionally, a longer duration of occupational exposure and closer proximity to the source of asbestos were linked to shorter survival times and lower survival rates. Among the patients with occupational asbestos exposure, the highest hazard ratios (HRs) were observed in those who worked in the production of asbestos-containing products across both cancer types. In contrast, significant HRs were only noted in mesothelioma patients who lived near asbestos industries, slate houses, and redevelopment areas, within the environmentally exposed group.

In plain English

This follow-up study used South Korean Ministry of Environment records on 546 malignant mesothelioma patients and 902 asbestos-related lung cancer patients identified as asbestos victims from 2009 to 2021. A structured questionnaire, checked against employment and residence records, classified exposure as occupational or environmental. Patients with both kinds were counted as occupational. For mesothelioma, median cancer-specific survival was 1.33 years with occupational exposure versus 1.75 years with environmental exposure. For lung cancer it was 2.92 versus 3.04 years. After adjusting for sex, age, smoking, cell type and treatment, occupational exposure had a hazard ratio for cancer-specific death of 1.31 (95% CI 1.06 to 1.62) in mesothelioma. In lung cancer it was 0.95 (0.75 to 1.20), which was not statistically significant. Among environmentally exposed patients, each additional 10 years of residence was associated with higher cancer-specific mortality (hazard ratio 1.12, 95% CI 1.04 to 1.21, for mesothelioma; 1.15, 1.05 to 1.25, for lung cancer). Work producing asbestos-containing products showed the highest job-type hazard ratios. The authors concluded that asbestos exposure may reduce survival. They noted they lacked fiber concentration data and information on education, income and genetics.

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: Follow-up (survival) study of patients identified through a national asbestos-victim surveillance system, using Cox proportional hazard models adjusted for sex, age at diagnosis, smoking status, cancer cell type and type of treatment
• Who was studied: 546 patients with malignant mesothelioma and 902 patients with asbestos-related lung cancer identified as asbestos victims in South Korea from 2009 to 2021, from South Korea Ministry of Environment data, followed to 31 December 2021. The article does not say whether the mesothelioma was pleural or peritoneal.
• Exposure: Occupational exposure was described by job type (extraction; production of asbestos-containing products such as cement, slate and fabric; construction; maintenance; others), work duration and age at first exposure. Environmental exposure was described by source (asbestos mine, asbestos industry, shipyard, slate house, redevelopment area, others), distance from the source, residence duration and age at first exposure. Co-exposure was counted as occupational. Fiber types and fiber concentrations were not measured.
• Main results:
  • Malignant mesothelioma: median survival was 1.33 years with occupational exposure (n = 286; 3-year survival 33.6%, 5-year 23.7%) versus 1.75 years with environmental exposure (n = 263; 47.5%, 39.2%). Lung cancer: 2.92 years with occupational exposure (n = 524; 72.3%, 66.0%) versus 3.04 years with environmental exposure (n = 378; 77.8%, 70.6%).
  • Adjusted hazard ratio for cancer-specific death, occupational versus environmental exposure, in malignant mesothelioma patients: 1.31 (95% CI 1.06, 1.62), p = 0.013
  • Adjusted hazard ratio for occupational versus environmental exposure in lung cancer patients: 0.95 (95% CI 0.75, 1.20), p = 0.669, not statistically significant
  • In mesothelioma patients, the hazard ratio rose with each 10-year increase in work duration: 1.10 (95% CI 1.00, 1.20). This was not observed in lung cancer patients (1.01, 95% CI 0.93, 1.09).
  • Compared with 'other' jobs, the highest hazard ratios were for production of asbestos-containing products. In lung cancer patients this was 1.92 (95% CI 1.18, 3.11), p = 0.008. In mesothelioma patients it was printed as 2.22 (95% CI 1.06, 6.19) with p = 0.077.
  • Among environmentally exposed patients, each 10-year increase in residence duration was associated with a higher adjusted hazard ratio for cancer-specific death. It was 1.12 (95% CI 1.04, 1.21) for mesothelioma and 1.15 (95% CI 1.05, 1.25) for lung cancer.
  • Per 1 km greater distance from the source, the hazard ratio was 0.87 (95% CI 0.78, 0.97) for mesothelioma. For lung cancer it was 0.86 (95% CI 0.73, 1.01), p = 0.069.
  • In mesothelioma patients, living near an asbestos industry (HR 2.17, 95% CI 1.16, 4.03), slate houses (HR 2.22, 95% CI 1.04, 4.75) or redevelopment areas (HR 2.10, 95% CI 1.10, 4.01) was associated with higher hazard ratios than 'other' sources. For lung cancer, no source type was statistically significant.
• The authors' conclusion: The authors concluded that their results offer more substantial evidence suggesting that asbestos exposure may reduce survival times of patients with malignant mesothelioma and asbestos-related lung cancer. They did not measure fiber type, but suggested that greater use of crocidolite and amosite in asbestos product factories might explain the higher hazard ratios for production work and for living near factories.
• Limitations the authors state:
  • Asbestos fiber concentration levels were not available for either occupational or environmental exposure, which limited exposure assessment
  • Educational and income levels were not considered because most respondents were reluctant to disclose them
  • Genetic factors such as BAP1 mutations were not considered because the data were not available in Korea

Topics

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Malignant Mesothelioma, Lung Cancer, Prognosis, Median Survival, Environmental Exposure, Occupational Exposure, Hazard Ratio.

Related studies

• Air pollution and survival in patients with malignant mesothelioma and asbestos-related lung cancer: a follow-up study of 1591 patients in South Korea — D.A. Huh, Y.H. Choi, et al. (2024)
• Occupational and environmental asbestos exposure and the risk of lung cancer in Korea: A case-control study in South Chungcheong Province of Korea — D.A. Huh, M.S. Kang, et al. (2021)
• Disease Latency according to Asbestos Exposure Characteristics among Malignant Mesothelioma and Asbestos-Related Lung Cancer Cases in South Korea — D.A. Huh, W.R. Chae, et al. (2022)
• Characteristics of asbestos fibers in lung tissue from occupational and environmental asbestos exposure of lung cancer patients in Busan, Korea — H.S. Jung, E.K. Park, et al. (2020)
• Occupational Burden of Asbestos-Related Diseases in Korea, 1998-2013: Asbestosis, Mesothelioma, Lung Cancer, Laryngeal Cancer, and Ovarian Cancer — D.M. Kang, J.E. Kim, et al. (2018)
• Asbestos-related occupational cancers compensated under the Industrial Accident Compensation Insurance in Korea — Y.S. Ahn, S.K. Kang (2009)

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