Asbestos and kidney cancer: the evidence supports a causal association

Our plain-English summary of Asbestos and kidney cancer: the evidence supports a causal association, by A.H. Smith, V.I. Shearn, R. Wood (American Journal of Industrial Medicine, 1989).

The study

• Authors: A.H. Smith, V.I. Shearn, R. Wood
• Journal: American Journal of Industrial Medicine
• Published: 1989;16(2):159-66
• Type of article: Review
• Cited by: 31 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. 000163).

Abstract

The role of asbestos in the etiology of lung cancer and of mesothelioma of the pleura and peritoneum has been well documented. The evidence for a causal association between asbestos and other human cancers is not as extensive but suggests that asbestos may be carcinogenic at several different sites. This paper is concerned specifically with a possible causal association between asbestos and human kidney cancer. A review of the evidence to date indicates that only three human studies have sufficient statistical power to detect an excess mortality from kidney cancer among workers exposed to asbestos. All three were occupational cohort studies, and two of these gave strong direct evidence for such an excess; a study of U.S. insulators (kidney cancer SMR = 2.22, 90% CI 1.44-3.30), and a study of U.S. asbestos products company workers (kidney cancer SMR = 2.76, 90% CI 1.29-5.18). The third study, of Italian shipyard workers, reported excess mortality from "cancers of the kidney, urinary bladder, and other urinary organs" (SMR = 1.98, 90% CI 1.42-2.70). Further support for a causal association includes studies finding asbestos fibers in human kidneys and urine, as well as reports of kidney tumors in two animal bioassays. It is concluded that asbestos should be regarded as a probable cause of human kidney cancer.

In plain English

This was a review of evidence on whether asbestos causes kidney cancer. The authors sought worker cohorts with lung cancer relative risks above 2; three gave kidney cancer information, two reporting kidney cancer deaths separately. Among U.S. and Canadian insulators, 18 kidney cancer deaths occurred versus 8.1 expected (standardized mortality ratio, SMR, 2.22; 90% confidence interval 1.44-3.30). Counting deaths 20 or more years after first exposure, with smoking considered, 15 occurred versus 8.5 expected (SMR 1.76; 90% interval 1.09-2.72). Among 1,074 retirees of a U.S. asbestos products company, seven kidney cancer deaths occurred versus 2.54 expected (SMR 2.76; 90% interval 1.29-5.18). Genoa, Italy, shipyard workers had 29 deaths from kidney, bladder and other urinary cancers combined versus 14.65 expected. For two other cohorts not reporting kidney cancer separately, the authors calculated 14% and 21% power to detect a doubled kidney cancer risk in subsets with lung cancer relative risks above 2. Fiber findings in human kidneys and urine and rat feeding studies were also reviewed. The authors concluded it seems probable that asbestos can cause human kidney cancer.

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: Review of published evidence (occupational cohort studies, a case-control study, fiber studies in human tissue and urine, and animal bioassays), with pooling of two cohorts and statistical power calculations
• Who was studied: Three published occupational cohorts that had lung cancer relative risks above 2 and gave kidney cancer information: insulation workers in the United States and Canada (17,800 men; Selikoff et al. 1979), 1,074 retirees from a U.S. asbestos products company (Enterline et al. 1987), and shipyard workers in Genoa, Italy (Puntoni et al. 1979). Two further cohorts (London factory workers; asbestos miners) were assessed for statistical power.
• Exposure: Occupational asbestos exposure in insulation work, asbestos products manufacture and shipyard work. The authors used lung cancer relative risk as an indirect measure of exposure. Fiber types are named only for the supporting evidence: amphibole fibers in urine, and chrysotile in the rat feeding studies.
• Main results:
  • U.S. and Canadian insulators: 18 kidney cancer deaths observed versus 8.1 expected, SMR 2.22 (90% confidence interval 1.44-3.30)
  • Insulators: after the original investigators reviewed medical and autopsy data, the count of kidney cancer deaths rose from 18 to 19. The authors took this to mean misdiagnosis was most unlikely to explain the excess.
  • Insulators, deaths 20 or more years after onset of exposure, with expected deaths calculated taking smoking into account: 15 observed versus 8.5 expected, SMR 1.76 (90% confidence interval 1.09-2.72)
  • U.S. asbestos products company retirees: 7 kidney cancer deaths versus 2.54 expected, SMR 2.76 (90% confidence interval 1.29-5.18)
  • Insulators and products company retirees combined: kidney cancer SMR 2.36 (90% confidence interval 1.64-3.29)
  • Neither of these two cohorts showed an excess of urinary bladder cancer deaths
  • Genoa shipyard workers: kidney cancer was reported only as part of a combined category. There were 29 deaths from cancers of the kidney, urinary bladder and other urinary organs combined, versus 14.65 expected, SMR 1.98 (90% confidence interval 1.42-2.70).
  • Two other large cohorts (London factory workers; asbestos miners) did not report kidney cancer separately. In their subsets with lung cancer relative risks above 2, the authors calculated power to detect a kidney cancer relative risk of 2 as 14% and 21% respectively.
  • Reviewed autopsy study of persons with asbestosis or pleural plaques: 38% overall had asbestos bodies in the kidneys, and 75% of those with the heaviest exposure
  • Reviewed rat study (Gibel et al.): of 42 Wistar rats fed filter material containing 52.6% chrysotile, 12 had malignant tumors with metastases, including 4 kidney carcinomas
• The authors' conclusion: The authors concluded that, on the evidence presented, it seems probable that asbestos exposure can cause human kidney cancer. In their abstract they state that asbestos should be regarded as a probable cause.
• Limitations the authors state:
  • Some asbestos cohort studies do not report kidney cancer rates at all
  • Smoking data were not available for the asbestos products company cohort
  • The shipyard study reported kidney cancer only within a combined urinary cancer category, and its workers had many other exposures (silica, polycyclic aromatic hydrocarbons, welding fumes), so a link to asbestos is less clear there
  • The power calculations for the London cohort are approximate, because they assume UK kidney cancer proportions are similar to those in the U.S.
  • Case-control studies could not address the question, because heavy occupational asbestos exposure is uncommon in the populations studied

Topics

Medical terms in this study, explained in our Lexicon: Etiology, Lung Cancer, Mesothelioma, Pleura, Peritoneum, Carcinogenic, Insulator.

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• Workplace exposure to asbestos and the risk of kidney cancer in Canadian men — C.E. Peters, M.É. Parent, et al. (2018)

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