Work-relatedness of lung cancer by smoking and histologic type in Korea

Our plain-English summary of Work-relatedness of lung cancer by smoking and histologic type in Korea, by Y.I. Lee, S.G. Lee, D.M. Kang, et al (Annals of Occupational and Environmental Medicine, 2014).

The study

• Authors: Y.I. Lee, S.G. Lee, D.M. Kang, J.E. Kim, Y.K. Kim, J.H. Leem, H.C. Kim
• Journal: Annals of Occupational and Environmental Medicine
• Published: 2014;26(1):43
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objectives: This study investigated the distribution of causative agents related to occupational lung cancer, their relationships with work, and associations between work-relatedness and the histologic type of lung cancer.

Methods: We used data from the occupational surveillance system in Korea in 2013. In addition, data from 1,404 participants diagnosed with lung cancer were collected through interviews. We included the patients' longest-held job in the analysis. Work-relatedness was categorized as "definite," "probable," "possible," "suspicious," "none," or "undetermined."

Results: Among the subjects, 69.3% were men and 30.7% were women. Regarding smoking status, current smokers were the most prevalent (35.5%), followed by non-smokers (32.3%), ex-smokers (32.2%). Regarding the causative agents of lung cancer, asbestos (1.0%) and crystalline silica (0.9%) were the most common in definite work-related cases, while non-arsenical insecticide (2.8%) was the most common in probable cases followed by diesel engine exhaust (1.9%) and asbestos (1.0%). Regarding histologic type, adenocarcinoma was the most common (41.7%), followed by squamous cell carcinoma (21.2%). Among current smokers, squamous cell carcinoma was the most common among definite and probable cases (13.4%), while non-small cell lung cancer was the least common (7.1%). Among non-smokers, squamous cell carcinoma was the most common (21.4%), while the least common was adenocarcinoma (1.6%).

Conclusions: Approximately, 9.5% of all lung cancer cases in Korea are occupational-related lung cancer. Well-known substances associated with lung cancer, such as crystalline silica, asbestos, and diesel engine exhaust, are of particular concern. However, the histologic types of lung cancer related to smoking were inconsistent with previous studies when work-relatedness was taken into account. Future studies are required to clarify the incidence of occupational lung cancer in agricultural workers exposed to non-arsenical insecticides and the associations between work-relatedness and the histologic type of lung cancer.

In plain English

This Korean study used 2013 surveillance data on 1,404 adults with newly diagnosed or tissue-confirmed lung cancer. Patients recruited at 8 hospitals in the middle and 10 in the southern regions of Korea were interviewed, and specialists judged whether each cancer was related to the patient's longest-held job. Overall, 2.2% were rated definitely and 7.3% probably work-related. All 31 definite cases were in men. Asbestos was the most common agent among definite cases (14 patients, 1.0% of all 1,404 patients), followed by crystalline silica (12 patients, 0.9%). Asbestos accounted for another 14 probable cases (1.0% of all patients). The most common agents among probable cases were non-arsenical insecticides (39 patients, 2.8% of all patients) and diesel engine exhaust (27 patients, 1.9%). Squamous cell carcinomas were rated work-related more often than adenocarcinomas in both smoking and non-smoking groups. The authors concluded that about 9.5% of Korean lung cancers are occupational, with crystalline silica, asbestos and diesel exhaust of specific concern. They also concluded that smoking-related tumor types differed from earlier studies once work-relatedness was considered. They noted that their cross-sectional design cannot establish cause.

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: Cross-sectional study using interview data from a national occupational surveillance system
• Who was studied: 1,404 patients aged 20 or older, recruited January to August 2013 at 8 hospitals in the middle and 10 in the southern regions of Korea. Each had lung cancer that was newly diagnosed or histopathologically confirmed. 973 were men (69.3%) and 431 were women (30.7%).
• Exposure: Occupational exposure was judged from each patient's longest-held job. The authors identified 24 occupational hazardous agents or processes, including asbestos (fiber type not specified), crystalline silica, diesel engine exhaust and non-arsenical insecticides. Work-relatedness was rated definite, probable, possible, suspicious, none or undetermined.
• Main results:
  • Of all 1,404 patients, 2.2% were rated definite and 7.3% probable work-related cases.
  • Together, 9.5% of all patients were probable or definite cases. Definite cases occurred only in men (31 of 973 men, 3.2%).
  • Asbestos was the most common agent among definite cases, with 14 cases (1.0% of all 1,404 patients, all men). Crystalline silica followed with 12 cases (0.9% of all patients).
  • Among probable cases, the most common agent was non-arsenical insecticides, with 39 cases (2.8% of all patients). Diesel engine exhaust followed with 27 cases (1.9% of all patients), then asbestos with 14 cases (1.0% of all patients).
  • With definite and probable cases combined, the leading agents were non-arsenical insecticides (2.8% of all patients), asbestos (2.0%), diesel engine exhaust (1.9%) and crystalline silica (1.3%).
  • Across all patients, adenocarcinoma was the most common tumor type (41.7%), followed by squamous cell carcinoma (21.2%).
  • In the smoking group, 38 squamous cell carcinomas were rated definite or probable work-related and 245 were not (13.4%; p = 0.0346 across tumor types). Among non-smokers, 3 were rated work-related and 11 were not (21.4%; p = 0.0004).
  • Adenocarcinomas were rated work-related less often. In the smoking group, 26 were work-related and 256 were not (9.2%). Among non-smokers, 5 were work-related and 299 were not (1.6%).
  • After adjusting for smoking, 41 squamous cell carcinomas were rated work-related and 256 were not (13.8%; Cochran-Mantel-Haenszel p = 0.0421).
• The authors' conclusion: The authors concluded that about 9.5% of all lung cancers in Korea are occupational, a share they called not insubstantial. They concluded that crystalline silica, asbestos and diesel engine exhaust are of specific concern. They also concluded that the tumor types linked to smoking were inconsistent with previous studies once work-relatedness was considered.
• Limitations the authors state:
  • The study sample may not be fully representative, because patients diagnosed at local hospitals tended to be concentrated at hospitals near Seoul.
  • Case definitions or evaluations of work-relatedness may differ by region among Korean surveillance studies.
  • Most patients had 2 or more jobs, but only the longest-held job was evaluated, so exposure to multiple carcinogens was not fully considered.
  • The cross-sectional design cannot determine causation.

Topics

Medical terms in this study, explained in our Lexicon: Lung Cancer, Crystalline, Adenocarcinoma, Squamous Cell Carcinoma, Non-Small Cell Lung Cancer.

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