Study of asbestos bodies in Japanese urban patients

Our plain-English summary of Study of asbestos bodies in Japanese urban patients, by K. Hiraoka, A. Horie, M. Kido (American Journal of Industrial Medicine, 1990).

The study

• Authors: K. Hiraoka, A. Horie, M. Kido
• Journal: American Journal of Industrial Medicine
• Published: 1990;18(5):547-54
• Cited by: 15 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 004477).

Abstract

To study whether low-level exposure to asbestos contributes to lung cancer risk, the asbestos body (AB) content in lung tissue was measured in 476 patients with lung cancer and 369 patients with other diseases, all from a Japanese industrialized city. Eleven patients with histologically confirmed asbestosis were included. The findings were stratified into four groups. A significant number of patients with lung cancer were seen in the groups with high counts, as compared to controls. There was no significant difference in histologic type and site of lung cancer among four groups. The patients with lung cancer in high count groups were significantly younger than those with lower counts. A significant number of smokers were seen in the groups with high AB counts among patients with lung cancer as compared to controls, even if the patients with asbestosis were excluded. These findings suggest that there may be a positive interaction of smoking and exposure to asbestos relative to the incidence of lung cancer even at a low exposure level.

In plain English

This study from Kitakyushu, Japan, counted asbestos bodies (coated fibers seen by light microscope) in lung tissue as a stand-in for past asbestos exposure. It compared 476 lung cancer patients (autopsied or operated on, 1979 to 1988) with 369 autopsied patients aged 35 or older with other diseases. Counts of 2,000 or more per gram of wet lung were found in 26 of 476 lung cancer patients (5.5%) and 6 of 369 controls (1.6%), a statistically significant difference. Counts of 20 to 1,999 were also significantly more frequent among lung cancer patients. Excluding 11 patients with asbestosis, lung cancer patients with higher counts were significantly younger (mean 65.40 vs 67.25 years). Among lung cancer patients, but not controls, the share of smokers of 15 or more cigarettes a day differed significantly across count groups. Cancer cell type and lobe did not differ significantly. The authors concluded there may be a positive interaction of smoking and asbestos exposure on lung cancer even at low exposure. They noted that asbestos bodies undercount fibers, especially chrysotile, and say little about when fibers were inhaled.

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: Comparison of lung-tissue asbestos body counts in lung cancer patients and in control patients with other diseases (case-control style pathology study)
• Who was studied: 476 lung cancer patients (337 autopsied, 139 operated on) from seven urban hospitals in Kitakyushu, Japan, with specimens from 1979 to 1988. Controls were 369 autopsied patients aged 35 or older with other diseases, all from one of those hospitals.
• Exposure: Asbestos bodies per gram of wet lung tissue, counted by light microscopy and used as a surrogate for prior asbestos exposure. Patients were grouped as less than 20, 20 to 199, 200 to 1,999, and 2,000 or more per gram. Fiber types and occupations were not reported.
• Main results:
  • Counts of 2,000 or more asbestos bodies per gram (group 4), compared with group 1, were significantly more frequent among lung cancer patients than controls (p less than 0.01). Per Table I, this was 26 of 476 lung cancer patients (5.5%) versus 6 of 369 controls (1.6%).
  • Counts of 20 to 1,999 per gram (groups 2 and 3 combined), compared with group 1, were significantly more frequent among lung cancer patients than controls (p less than 0.05). Per Table I, lung cancer patients numbered 66 (13.9%) and 45 (9.5%); controls numbered 41 (11.1%) and 26 (7.1%).
  • Excluding the 11 patients with asbestosis, lung cancer patients with 20 or more asbestos bodies per gram were significantly younger than those in group 1 (mean 65.40 vs 67.25 years, p less than 0.05). There was no significant age difference among controls.
  • Excluding patients with asbestosis, the number of smokers (15 or more cigarettes per day) differed significantly across asbestos body groups among lung cancer patients (p less than 0.001) but not among controls. Smoking data were available for 439 lung cancer patients and 356 controls.
  • Among lung cancer patients, there were significantly more men in groups 3 and 4 than in group 1.
  • Histologic type and lobe of the lung cancer did not differ significantly among the four asbestos body groups.
  • Eleven patients, all male, had histologically confirmed asbestosis. Ten of them had lung cancer (nine in group 4, one in group 3). The remaining patient, a control, was in group 4.
• The authors' conclusion: The authors concluded that their findings suggest there may be a positive interaction between smoking and asbestos exposure in the incidence of lung cancer, even at a low exposure level.
• Limitations the authors state:
  • Only a small proportion of inhaled fibers become coated asbestos bodies, so many uncoated fibers go uncounted.
  • Asbestos body counts say little about when the fibers were inhaled.
  • Amphiboles are far more likely to be coated than chrysotile.
  • Longer fibers are coated more readily than shorter fibers.
  • With more subjects, differences in cancer cell type and site might have reached significance.

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Bodies, Lung Cancer, Asbestos Body Formation.

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