Obstructive airway disease as a risk factor for asbestos-associated malignancy

Our plain-English summary of Obstructive airway disease as a risk factor for asbestos-associated malignancy, by P. Harber, A. Oren, Z. Mohsenifar, et al (Journal of Occupational Medicine., 1986).

The study

• Authors: P. Harber, A. Oren, Z. Mohsenifar, M. Lew
• Journal: Journal of Occupational Medicine.
• Published: 1986;28(2):82-6
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 001182).

Abstract

A case-control study of a heavily asbestos-exposed group was performed to determine if obstructive airway disorder is an independent risk factor for developing asbestos-associated malignancies. From a group of 1,500 asbestos workers who had previously undergone careful evaluation, 18 case employees were identified. Each case employee was matched by smoking status, pack-years, age, and years of asbestos exposure to a single referent, a member of the same exposed population known to be free of malignancy. The spirometry results, obtained prior to the clinical manifestation of the cancer, were compared. The FEV1/FVC ratio and the FEV1/height3 ratio were lower (P less than .05, P less than .10, respectively) in the case employees. These results suggest that obstructive airway disease may be an independent risk factor for cancer.

In plain English

The authors ran a nested case-control study within about 1,500 heavily asbestos-exposed shipyard workers evaluated at three UCLA-affiliated hospitals in 1979 to 1983. The article does not give these workers' fiber types. Cancer status came from letters and calls to workers and families. Of 22 asbestos-associated cancers found, 18 were analyzed: the text calls them 14 lung, 3 gastrointestinal and 1 probable laryngeal cancer, but its table lists the other four as kidney, throat, colon and stomach. Each case was matched to one cancer-free worker from the group by race, hospital, smoking, pack-years, age and exposure duration. The authors compared breathing tests (spirometry) done before the cancers became clinically apparent. Across all pairs, the FEV1/FVC ratio, a measure of airflow obstruction, was lower in cases (p less than .05). The FEV1-to-height-cubed ratio difference was borderline by t test (p less than .10). The authors concluded that the study raises the possibility that obstructive airway disease is a risk factor for asbestos-associated cancers. They noted the few cases and reliance on family reports, and called for a definitive study.

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: Nested case-control study, comparing spirometry from earlier evaluations between cancer cases and matched cancer-free workers from the same cohort
• Who was studied: About 1,500 heavily asbestos-exposed shipyard workers referred to three UCLA-affiliated hospitals (Center for Health Sciences, Harbor-UCLA, Cedars-Sinai) and evaluated between 1979 and 1983. All had filed a Federal Employees Compensation Act claim and/or had possible asbestos-associated X-ray abnormalities. Five females were excluded. 18 cancer cases were each matched to one cancer-free control.
• Exposure: Heavy occupational asbestos exposure in shipyard work. Median exposure duration was 24 years. The article does not state the fiber types these workers were exposed to. Fiber counts were not available, so exposure intensity could not be quantified.
• Main results:
  • 22 asbestos-associated cancers were identified. 4 were excluded (incomplete records, cancer already present at evaluation, prior lung surgery). The text describes the remaining 18 cases as 14 lung cancers, 3 gastrointestinal malignancies and 1 probable laryngeal cancer. Table 1 lists the four non-lung cases as kidney, 'throat', colon and stomach.
  • Cases and matched controls did not differ significantly in age or duration of exposure. On average, cases were 1.2 years older and had been exposed 0.1 year longer.
  • Across all case-control pairs, the FEV1/FVC ratio was lower in cancer cases than in controls (P < .05 by t test and Wilcoxon test).
  • Across all pairs, the FEV1/height-cubed ratio difference was borderline significant (P < .10 by t test).
  • The mean FEV1 difference of .352 L was of borderline significance (P < .10), and only by the Wilcoxon test.
  • In the lung cancer pairs, only the FEV1/FVC ratio difference reached statistical significance (P < .05). Other airflow measures showed a trend toward worse values in those who later had lung cancer.
  • There were only two pairs of never smokers, so they were not tested separately.
• The authors' conclusion: The authors concluded that the study raises the possibility that obstructive airway disease may be a risk factor for developing asbestos-associated malignancies. They stated that a definitive study with longer, more intense follow-up is needed.
• Limitations the authors state:
  • The relatively small number of workers with cancer means further study is needed.
  • Cancer status depended on reports from workers and their families, so misclassification is possible. The association could be spurious.
  • No ICDA codes or verified death certificate information were obtained.
  • Fiber counts were unavailable, so exposure intensity could not be quantified.
  • Matching on exposure relied on worker and employer reports, which could have made the matching inaccurate. Incorrect smoking information could have a similar effect.
  • Cancers not yet clinically apparent at the initial examination may have had subtle effects that produced apparent airway obstruction.
  • There was no further formal follow-up of the cohort.

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: Case-Control Study, Asbestos Exposure, Spirometry, FEV1/FVC Ratio, FEV1.

Related studies

• The relative importance of clinical, radiological and pulmonary function variables in evaluating asbestosis and chronic obstructive airway disease in asbestos workers — G.M. Regan, B. Tagg, et al. (1971)
• Prevalence of obstructive lung disease in a general population: relation to occupational title and exposure to some airborne agents — P.S. Bakke, V. Baste, et al. (1991)
• Total lung capacity. An insensitive measure of impairment in patients with asbestosis and chronic obstructive pulmonary disease? — S. Barnhart, L.D. Hudson, et al. (1988)
• Auscultated forced expiratory time as a clinical and epidemiologic test of airway obstruction — D.G. Kern, S.R. Patel (1991)
• CT scan screening for lung cancer: risk factors for nodules and malignancy in a high-risk urban cohort — A.K. Greenberg, F. Lu, et al. (2012)
• Asbestos exposure and airways obstruction — M.G. Pearson (1991)

Browse more research in Journal of Occupational Medicine., or return to medical research.