Clinical study of asbestos-related lung cancer in Japan with special reference to occupational history

Our plain-English summary of Clinical study of asbestos-related lung cancer in Japan with special reference to occupational history, by T. Kishimoto, K. Gemba, N. Fujimoto, et al (Cancer Science, 2010).

The study

• Authors: T. Kishimoto, K. Gemba, N. Fujimoto, K. Onishi, I. Usami, K. Mizuhashi, K. Kimura
• Journal: Cancer Science
• Published: 2010;101(5):1194-8
• Cited by: 16 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

A total of 152 patients with asbestos-related lung cancer recognized by the criteria of Japanese compensation law for asbestos-related diseases were examined and compared with 431 patients with non-asbestos-related lung cancer. Male comprised 96% of patients. Ages ranged from 50 to 91 years with a median of 72 years. Eighty-nine percent were smokers or ex-smokers. Almost all patients had occupational histories of asbestos exposure. The median duration of asbestos exposure was 31 years and the median latency period was 47 years. Thirty-four percent of patients exhibited asbestosis and 81% exhibited pleural plaques by radiography. Regarding asbestos particles in the lung for 73 operated or autopsied patients, 62% had more than 5,000 particles per gram. On the other hand, 100% of non-asbestos-related lung cancer patients had <5000 particles per gram with a median of 554 particles. The number of asbestos bodies in the lung, male gender, absence of symptoms, smoking index, and early stage of cancer were significantly much more than those of non-asbestos-related lung cancer. In this study, a diagnosis of asbestos-related lung cancer was made in 34% of patients by asbestosis, in 62% by presence of both pleural plaques and more than 10 years' occupational asbestos exposure, and in 4% by more than 5000 asbestos particles per gram of lung tissue. Occupational histories, duration of asbestos exposure, and pleural plaques are common categories for the recognition of asbestos-related lung cancer in Japan.

In plain English

This retrospective study compared 152 patients at 18 Rosai hospitals in Japan (2000 to 2008) whose lung cancer met Japanese compensation-law criteria for asbestos-related lung cancer, with 431 lung cancer patients at Okayama Rosai Hospital (1997 to 2007) whose cancer did not. In the asbestos-related group, 146 were men, the median age was 72, and 134 were smokers or ex-smokers. Almost all had worked with asbestos, most often in shipbuilding and construction, for a median of 31 years. Median time from first exposure to cancer was 47 years. On imaging, 51 (34%) had asbestosis and 122 (81%) had pleural plaques. Of 73 patients whose lung tissue was examined, 45 (62%) had more than 5000 asbestos particles per gram and 14 (19%) had fewer than 1000. The 23 comparison patients tested had a median of 554 asbestos particles per gram. Overall survival was 17.4 versus 19.2 months; the difference was not statistically significant. The authors concluded that occupational history, exposure duration and pleural plaques were common grounds for recognition in Japan. They called attributing lung cancer without asbestosis to asbestos still controversial.

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: Retrospective clinical study comparing patients with asbestos-related lung cancer (as defined by Japanese compensation-law criteria) with patients with non-asbestos-related lung cancer
• Who was studied: 152 patients with asbestos-related lung cancer treated at 18 Rosai hospitals in Japan from 2000 to 2008 (146 male, 6 female), compared with 431 patients with non-asbestos-related lung cancer treated at Okayama Rosai Hospital from 1997 to 2007
• Exposure: Occupational asbestos exposure, based on work histories. 150 of 152 patients had occupational exposure. Jobs included shipbuilding (34), construction (29), asbestos product making (15), piping (15) and insulation (14). Median exposure duration was 31 years (range 1 to 60, 146 patients). Asbestos particles in lung tissue were counted by light (phase-contrast) microscopy. Fiber types were not measured.
• Main results:
  • In the asbestos-related lung cancer group, 146 of 152 were male and ages ranged from 50 to 91 years, with a median of 72
  • In the asbestos-related group, 15 patients (10%) were non-smokers and 134 were smokers or ex-smokers
  • Compared with the non-asbestos-related group, the asbestos-related group had higher proportions of men (96.1% vs 72.2%), patients without symptoms (55.2% vs 39.9%), smokers (90.1% vs 79.6%) and early-stage disease. Table 1 gives p less than 0.01 for each.
  • Overall survival was 17.4 months in the asbestos-related group (25% at 5 years) and 19.2 months in the non-asbestos-related group (25% at 5 years). The authors reported the difference as not statistically significant.
  • In multivariate analysis of both groups combined, age, gender and stage were prognostic factors, but asbestos exposure and pathology were not. For asbestos, the multivariate result was Exp(b) 1.051 (95% CI 0.816 to 1.353), P = 0.699.
  • On radiography, 51 asbestos-related patients (34%) had asbestosis and 122 (81%) had pleural plaques
  • 94 asbestos-related patients (62%) qualified on the criterion of pleural plaques with more than 10 years of occupational exposure. In the flow chart, 51 qualified by asbestosis and 7 by more than 5000 particles per gram of lung tissue.
  • Of 73 asbestos-related patients with lung tissue counts, 45 (62%) had more than 5000 asbestos particles per gram of dry lung tissue, and 21 (29%) exceeded 50,000
  • 14 of the 73 asbestos-related patients with counts (19%) had fewer than 1000 particles per gram, which the authors called the non-exposed citizen level. These 14 had pleural plaques with more than 10 years of occupational exposure.
  • The 23 non-asbestos-related lung cancer patients with counts had 0 to 3751 asbestos particles per gram of lung tissue, with a median of 554
  • In the asbestos-related group, the latency from first exposure to lung cancer ranged from 5 to 71 years, with a median of 47 years
• The authors' conclusion: The authors concluded that occupational histories, duration of asbestos exposure and pleural plaques are the common categories used to recognize asbestos-related lung cancer in Japan
• Limitations the authors state:
  • The authors note that it remains controversial whether lung cancer in the absence of asbestosis can be attributed to asbestos exposure
  • The authors state that more patients are needed and that criteria for diagnosing asbestos-related lung cancer without asbestosis need clarifying
  • Two construction workers with asbestosis had fewer than 5000 particles. The authors state their fibers should be examined by electron microscopy.
  • 47% of asbestos-related patients were heavy smokers. The authors suggest their lung cancer was related to smoking as well as asbestos.

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 History, Asbestos Exposure, Latency, Pleural Plaques, Asbestos Bodies.

Related studies

• Clinical investigation of malignant mesothelioma in Japan — N. Fujimoto, K. Aoe, et al. (2010)
• A case-control study of lung cancer with special reference to asbestos exposure — M. Minowa, S. Hatano, et al. (1991)
• Radiotherapy in the treatment of malignant mesothelioma of the pleura, with special reference to its use in palliation — S.R. Davis, L. Tan, et al. (1994)
• Evaluation of pleural disease using MR and CT. With special reference to malignant pleural mesothelioma — A. Knuuttila, L. Kivisaari, et al. (2001)
• Clinical Investigation of Benign Asbestos Pleural Effusion — N. Fujimoto, K. Gemba, et al. (2015)
• National survey of malignant mesothelioma and asbestos exposure in Japan — K. Gemba, N. Fujimoto, et al. (2012)

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