Urothelial cancer and some industry-related chemicals: an evaluation of the epidemiologic literature

Our plain-English summary of Urothelial cancer and some industry-related chemicals: an evaluation of the epidemiologic literature, by G. Steineck, N. Plato, S.E. Norell, et al (American Journal of Industrial Medicine, 1990).

The study

• Authors: G. Steineck, N. Plato, S.E. Norell, C. Hogstedt
• Journal: American Journal of Industrial Medicine
• Published: 1990;17(3):371-91
• Type of article: Review
• Cited by: 65 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. 000044).

Abstract

In a previous cohort study by our group, certain industry-related chemicals were judged as warranting further attention as possible urothelial carcinogens. In this paper, the epidemiologic literature of cancer of the lower urinary tract is evaluated for these substances. We would like to add combustion gases/soot from coal to the substances considered as increasing the risk of urothelial cancer. It is, however, uncertain whether this risk is due to contaminants of aromatic amines in tar volatiles or whether it depends on other agents, such as nitroarenes or polycyclic aromatic hydrocarbons. Furthermore, we find some support for the hypothesis that exposure to chlorinated aliphatic hydrocarbons increases the risk of urothelial cancer. For creosote, cutting fluids and cutting oils, hair dyes, and polychlorinated biphenyls, data are scarce. Available data do not support the hypothesis that asbestos is associated with urothelial cancer. "Publication bias," such that only limited information was available, was judged to be a potential problem in the review for many, but not all, of the substances investigated.

In plain English

This article was a review of earlier studies, not a new study. The authors evaluated published epidemiologic studies of urothelial cancer of the lower urinary tract for chemicals flagged in their own earlier cohort study. They added asbestos because it causes cancer of the pleura and lung. The review drew on 24 case-referent studies and a set of cohort studies. An industrial hygienist, without seeing the results, judged which job titles involved each exposure. For asbestos, Selikoff and colleagues found a relative risk of 1.0 (95% confidence interval 0.4 to 1.9; 9 exposed cases) among asbestos-exposed workers. Acheson and colleagues, studying workers exposed to amosite asbestos, found 0.9 (0.1 to 3.3; 2 exposed cases). All case-referent studies had estimates near or below 1. The authors' own census-based study showed a somewhat increased risk of renal pelvis cancer, but tissue slides were not reviewed, so other kidney tumours may have been misclassified. The authors concluded that the available data did not support the hypothesis that asbestos increases the risk of urothelial cancer. They warned that selective reporting by the reviewed studies (publication bias) may have distorted the overall picture.

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 the published epidemiologic literature (case-referent and cohort studies) on urothelial cancer of the lower urinary tract and selected industry-related chemicals
• Who was studied: Published studies known to the authors in November 1987: 24 case-referent studies, plus cohort studies found through earlier reviews, MEDLINE and CANCERLIT. Studies using the proportionate mortality ratio were excluded. The results reported are for men classified as exposed.
• Exposure: Combustion gases/soot from coal, chlorinated aliphatic hydrocarbons, creosote, cutting fluids and cutting oils, hair dyes, polychlorinated biphenyls, and asbestos. Asbestos was added because it is a carcinogen for the pleura and lung. Exposure was usually inferred from occupational titles judged by an industrial hygienist.
• Main results:
  • Asbestos: Selikoff et al. (1979) observed a relative risk of urothelial cancer of 1.0 among workers exposed to asbestos. Table X gives a 95% confidence interval of 0.4 to 1.9, based on 9 observed exposed cases.
  • Asbestos: Acheson et al. (1984), studying workers exposed to amosite asbestos, obtained an estimate below unity. Table X gives a relative risk of 0.9 with a 95% confidence interval of 0.1 to 3.3, based on 2 observed exposed cases.
  • Asbestos: in the authors' census-based study (Steineck et al.), men assigned exposure to asbestos had a somewhat increased relative risk of cancer of the renal pelvis. No slide review was carried out, so adenocarcinoma of the renal parenchyma may have been misclassified as urothelial cancer of the renal pelvis.
  • Asbestos: all case-referent studies had estimates of relative risk near or below unity.
  • Chlorinated aliphatic hydrocarbons: the authors judged that the data gave some support for a link with urothelial cancer.
  • Other agents: the authors judged the data on cutting fluids and cutting oils insufficient and the data on creosote scant. No judgment could be made for polychlorinated biphenyls. They found good support for an increased risk among barbers/hairdressers, but noted that carcinogens other than hair dyes in that work environment could explain some or all of it.
  • Of the reviewed case-referent studies, 60% did not present information on all occupations investigated.
• The authors' conclusion: The authors concluded that available data did not support the hypothesis that asbestos exposure increases the risk of urothelial cancer. They considered certain combustion gases/soot from coal as causing an increase in that risk, while noting it remained to be determined which agent was responsible.
• Limitations the authors state:
  • Because many studies reported only selected occupations, the review may suffer from publication bias that gives a false overall impression of increased risk.
  • The review was restricted to epidemiologic data on urothelial cancer. Human data on other cancers and animal studies were not included.
  • Exposure to specific chemicals usually had to be inferred from occupational titles.
  • None of the cohort studies had information on tobacco habits.
  • Many estimates were based on small numbers.

Topics

Medical terms in this study, explained in our Lexicon: Cohort Study.

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