Numbers of asbestos bodies in urban patients with lung cancer and gastrointestinal cancer and in matched controls

Our plain-English summary of Numbers of asbestos bodies in urban patients with lung cancer and gastrointestinal cancer and in matched controls, by A.M. Churg, M.L. Warnock (Chest, 1979).

The study

• Authors: A.M. Churg, M.L. Warnock
• Journal: Chest
• Published: 1979;76(2):143-9
• Cited by: 33 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. 001018).

Abstract

We compared the numbers of asbestos bodies extracted from the lungs of 103 patients with lung cancer and 50 patients with gastrointestinal malignant neoplasms to the numbers of bodies extracted from lungs of control patients matched for age, sex, smoking habits, and, in some cases, occupation. All patients were urban dwellers over the age of 40 years, and none was a primary asbestos worker. No differences in the counts of asbestos bodies were observed between the tested and control populations. The numbers of asbestos bodies did correlate well with occupation; the highest counts were found in male manual laborers. We conclude that in the urban population studied herein, the numbers of asbestos bodies alone do not correlate with the presence of pulmonary or gastrointestinal carcinoma; however, uncoated asbestos fibers are also known to be present in the lung, and the possibility that such tumors may be related to the numbers of these fibers in lungs remains to be explored.

In plain English

This matched case-control study, done at the University of Chicago Medical Center from February 1974 to May 1977, counted asbestos bodies by light microscopy in lung tissue from urban patients over 40, none of them primary asbestos workers. The authors compared 103 patients with lung cancer and 50 with cancer of the esophagus, stomach or colon against controls matched for age, sex and smoking. Sixty of the 69 men with lung cancer were also matched by occupation. Median counts per gram of wet lung were 11 for women with lung cancer and 13 for their controls, and 33 versus 44 for men. With gastrointestinal cancer, medians were 27 versus 15 in women and 20 versus 40 in men. No difference was statistically significant. Counts did vary by job: 60 percent of construction workers, 41 percent of steel workers and 25 percent of other male manual laborers had over 100 bodies per gram, against 7 percent of white-collar men and women. The authors concluded that asbestos bodies in this population were not associated with these cancers. They cautioned that this did not mean there was no danger, because uncoated fibers, generally chrysotile, were not counted.

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: Matched case-control study of lung tissue from autopsies and lung-cancer surgery, with asbestos bodies counted by light microscopy without knowledge of disease or occupation
• Who was studied: Lung samples were available from 363 patients seen at the University of Chicago Medical Center between February 1974 and May 1977. They were 103 patients with lung cancer (66 autopsies, 37 surgical resections), 50 patients dying with cancer of the esophagus, stomach or colon, and 210 controls. All were urban dwellers (more than 20 years in a city of over 100,000) over age 40, and none was a primary asbestos worker. Six patients with asbestosis were analyzed for comparison.
• Exposure: Numbers of asbestos bodies per gram of wet lung, judged against occupation, smoking and age. Uncoated fibers were not counted. In the authors' related work, over 95 percent of ferruginous bodies from the general population had amphibole asbestos cores.
• Main results:
  • Counts in patients with lung cancer ranged from zero to 9,200 per gram of lung. Counts in controls ranged from zero to 1,980 per gram.
  • Women with lung cancer had a median of 11 bodies per gram, against 13 for their matched controls. Men with lung cancer had a median of 33 per gram, against 44 for their matched controls.
  • Comparing each lung-cancer patient with a matched control showed no significant differences. This held for the sign test and Wilcoxon's test, and the Kolmogorov-Smirnov comparisons were also not significant.
  • Women with gastrointestinal cancer had a median of 27 bodies per gram, against 15 for their matched controls. Men with gastrointestinal cancer had a median of 20 per gram, against 40 for their controls. The differences were not significant.
  • Overall, the authors found no differences in asbestos body numbers between either lung-cancer or gastrointestinal-cancer patients and their matched controls.
  • Counts were associated with occupation. More than 100 bodies per gram were found in 60 percent of construction workers, 41 percent of steel workers and 25 percent of other male manual laborers, compared with 7 percent of men and women with white-collar occupations.
  • Among male manual laborers, counts did not increase with age or with pack-years smoked.
  • The six patients with asbestosis had 8,000 to 520,000 bodies per gram. Only seven counts in the study population were over 800 per gram.
• The authors' conclusion: The authors concluded that, for practical purposes, asbestos bodies in this matched urban population were not associated with lung or gastrointestinal cancer. They said the possible role of total fibers, including uncoated fibers, remained to be studied.
• Limitations the authors state:
  • Only asbestos bodies were counted. Uncoated asbestos fibers (generally chrysotile), which may be found in most lungs, were not measured, and total fibers would need to be measured in a similar controlled study.
  • The authors stated that their negative findings should not yet be read as showing no danger to the general population from asbestos.
  • Even a strong correlation between body counts and cancer would not by itself establish an increased incidence of cancer. That would require incidence studies in large populations.
  • Results are difficult to compare with those of other laboratories, because few details of methods are published.
  • For most of the asbestosis cases, only a limited amount of lung was available, and replicate counts in scarred lungs varied widely.

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, Neoplasm, Habit, Carcinoma.

Related studies

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• Simple nutritional intervention in patients with advanced cancers of the gastrointestinal tract, non-small cell lung cancers or mesothelioma and weight loss receiving chemotherapy: a randomised controlled trial — C. Baldwin, A. Spiro, et al. (2011)
• Asbestos exposure and gastrointestinal malignancy review and meta-analysis — H. Frumkin, J. Berlin (1988)
• Investigating possible effects of abestos in city water: surveillance of gastrointestinal cancer incidence in Duluth, Minnesota — B.S. Levy, E. Sigurdson, et al. (1976)
• In vitro approaches for determining mechanisms of toxicity and carcinogenicity by asbestos in the gastrointestinal and respiratory tracts — B.T. Mossman (1983)

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