A case-control study of the relationship between the risk of colon cancer in men and exposures to occupational agents

Our plain-English summary of A case-control study of the relationship between the risk of colon cancer in men and exposures to occupational agents, by M.S. Goldberg, M.E. Parent, J. Siemiatycki, et al (American Journal of Industrial Medicine, 2001).

The study

• Authors: M.S. Goldberg, M.E. Parent, J. Siemiatycki, M. Désy, L. Nadon, L. Richardson, R. Lakhani, B. Latreille, M.F. Valois
• Journal: American Journal of Industrial Medicine
• Published: 2001;39(6):531-46
• Cited by: 46 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: We conducted a population-based case-control study in Montreal, Canada, to explore associations between hundreds of occupational circumstances and several cancer sites, including colon.

Methods: We interviewed 497 male patients with a pathologically confirmed diagnosis of colon cancer, 1514 controls with cancers at other sites, and 533 population-based controls. Detailed job histories and relevant potential confounding variables were obtained, and the job histories were translated by a team of chemists and industrial hygienists into a history of occupational exposures.

Results: We found that there was reasonable evidence of associations for men employed in nine industry groups (adjusted odds ranging from 1.1 to 1.6 per a 10-year increase in duration of employment), and in 12 job groups (OR varying from 1.1 to 1.7). In addition, we found evidence of increased risks by increasing level of exposures to 21 occupational agents, including polystyrene (OR for "substantial" exposure (OR(subst)) = 10.7), polyurethanes (OR(subst) = 8.4), coke dust (OR(subst) = 5.6), mineral oils (OR(subst) = 3.3), polyacrylates (OR(subst) = 2.8), cellulose nitrate (OR(subst) = 2.6), alkyds (OR(subst) = 2.5), inorganic insulation dust (OR(subst) = 2.3), plastic dusts (OR(subst) = 2.3), asbestos (OR(subst) = 2.1), mineral wool fibers (OR(subst) = 2.1), glass fibers (OR(subst) = 2.0), iron oxides (OR(subst) = 1.9), aliphatic ketones (OR(subst) = 1.9), benzene (OR(subst) = 1.9), xylene (OR(subst) = 1.9), inorganic acid solutions (OR(subst) = 1.8), waxes, polishes (OR(subst) = 1.8), mononuclear aromatic hydrocarbons (OR(subst) = 1.6), toluene (OR(subst) = 1.6), and diesel engine emissions (OR(subst) = 1.5). Not all of these effects are independent because some exposures occurred contemporaneously with others or because they referred to a group of substances.

Conclusions: We have uncovered a number of occupational associations with colon cancer. For most of these agents, there are no published data to support or refute our observations. As there are few accepted risk factors for colon cancer, we suggest that new occupational and toxicologic studies be undertaken focusing on the more prevalent substances reported herein.

Copyright 2001 Wiley-Liss, Inc.

In plain English

This population-based case-control study in Montreal, Canada, looked for links between colon cancer in men and hundreds of workplace exposures. The authors interviewed 497 men aged 35 to 70 who were diagnosed with colon cancer between 1979 and 1985. They compared them with 2047 control men: 1514 with other cancers and 533 from the general population. Chemists and industrial hygienists turned each man's job history into estimated exposures to about 300 agents. The authors reported associations with 21 agents, but some of these overlapped with each other. For asbestos, men with "substantial" exposure (18 cases) had an odds ratio of 2.1 (95% CI 1.1 to 4.0). Men with lesser exposure (60 cases) had an odds ratio of 0.9 (0.6 to 1.3). When other workplace exposures were also taken into account, the asbestos odds ratio was 1.8 (0.9 to 3.6). The authors described risk as rising with the frequency, concentration and duration of asbestos exposure. They noted that they had no data on diet, physical activity or family history. They concluded that new studies should focus on the more common substances identified.

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: Population-based case-control study analysed with unconditional logistic regression
• Who was studied: Men aged 35 to 70 living in greater Montreal and diagnosed 1979 to 1985. There were 497 interviewed colon cancer cases (of 607 eligible, 82% response). The pooled control group had 2047 men: 1514 with cancers at other sites (excluding lung, peritoneum and other digestive cancers) and 533 population controls.
• Exposure: About 300 chemical and physical agents, including asbestos (fiber type not specified), assigned by experts from detailed job histories. Exposure was grouped as unexposed, nonsubstantial or substantial.
• Main results:
  • Asbestos, pooled controls, adjusted for nonoccupational factors: substantial exposure (18 exposed cases) gave an odds ratio of 2.1 (95% CI 1.1 to 4.0). Nonsubstantial exposure (60 exposed cases) gave an odds ratio of 0.9 (95% CI 0.6 to 1.3).
  • Asbestos, after also adjusting for other occupational exposures: substantial exposure gave an odds ratio of 1.8 (95% CI 0.9 to 3.6). These adjustments weakened most associations; asbestos was not among the seven agents that kept their strength.
  • The authors reported consistent evidence of increasing relative risks for asbestos (and seven other agents) with increasing frequency, concentration and duration of exposure.
  • Lifetime prevalence of asbestos exposure in the study population was 17%. The most common occupations were motor vehicle mechanics, welders and flame cutters, and pipefitters and plumbers.
  • Overall, associations were found with 21 agents, which were not all independent. Inorganic insulation dust was highly correlated with asbestos.
• The authors' conclusion: The authors concluded that they had uncovered several occupational associations with colon cancer, most without published data to support or refute them. They suggested new occupational and toxicologic studies focusing on the more prevalent substances.
• Limitations the authors state:
  • The age cut-off of 70 years may have prevented detection of risks from hazards with long induction periods.
  • Exposure levels for most subjects may have been too low to produce a detectable increase in risk.
  • There was no information on some risk factors, including hereditary risks, diet and physical activity.
  • Several agents had fewer than 10 substantially exposed cases, so their estimates were statistically very uncertain.
  • Some exposures occurred together or referred to groups of substances, so the associations are not all independent.

Topics

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

Medical terms in this study, explained in our Lexicon: Case-Control Study, Colorectal Cancer, Confounding, Occupational Exposure.

Related studies

• Identification of occupational cancer risks in British Columbia, Canada: a population-based case-control study of 1,155 cases of colon cancer — R. Fang, N. Le, et al. (2011)
• The INTEROCC case-control study: risk of meningioma and occupational exposure to selected combustion products, dusts and other chemical agents — D.M. McElvenny, M. van Tongeren, et al. (2018)
• Colon cancer, physical activity, and occupational exposures. A case-control study — M. Fredriksson, N.O. Bengtsson, et al. (1989)
• INTEROCC case-control study: lack of association between glioma tumors and occupational exposure to selected combustion products, dusts and other chemical agents — A. Lacourt, E. Cardis, et al. (2013)
• Asbestos and colon cancer: lack of association in a large case-control study — D.H. Garabrant, R.K. Peters, et al. (1992)
• Occupational risk factors for renal cell carcinoma: agent-specific results from a case-control study in Germany. MURC Study Group. Multicenter urothelial and renal cancer study — B. Pesch, J. Haerting, et al. (2000)

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