Occupational asbestos exposure and risk of esophageal, gastric and colorectal cancer in the prospective Netherlands Cohort Study

Our plain-English summary of Occupational asbestos exposure and risk of esophageal, gastric and colorectal cancer in the prospective Netherlands Cohort Study, by N.S. Offermans, R. Vermeulen, A. Burdorf, et al (International Journal of Cancer, 2014).

The study

• Authors: N.S. Offermans, R. Vermeulen, A. Burdorf, R.A. Goldbohm, A.P. Keszei, S. Peters, T. Kauppinen, H. Kromhout, P.A. van den Brandt
• Journal: International Journal of Cancer
• Published: 2014;135(8):1970-7
• Cited by: 33 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The evidence for an association between occupational asbestos exposure and esophageal, gastric and colorectal cancer is limited. We studied this association specifically addressing risk differences between relatively low and high exposure, risk associated with cancer subtypes, the influence of potential confounders and the interaction between asbestos and smoking in relation to cancer risk. Using the Netherlands Cohort Study (n = 58,279 men, aged 55-69 years at baseline), asbestos exposure was estimated by linkage to a job-exposure matrix. After 17.3 years of follow-up, 187 esophageal, 486 gastric and 1,724 colorectal cancer cases were available for analysis. The models adjusted for age and family history of cancer showed that mainly (prolonged) exposure to high levels of asbestos was statistically significantly associated with risk of esophageal adenocarcinoma (EAC), total and distal colon cancer and rectal cancer. For overall gastric cancer and gastric non-cardia adenocarcinoma (GNCA), also exposure to lower levels of asbestos was associated. Additional adjustment for lifestyle confounders, especially smoking status, yielded non-significant associations with overall gastric cancer and GNCA in the multivariable-adjusted model, except for the prolonged highly exposed subjects (tertile 3 vs. never: HR 2.67, 95% CI: 1.11-6.44 and HR 3.35, 95% CI: 1.33-8.44, respectively). No statistically significant additive or multiplicative interaction between asbestos and smoking was observed for any of the studied cancers. This prospective population-based study showed that (prolonged) high asbestos exposure was associated with overall gastric cancer, EAC, GNCA, total and distal colon cancer and rectal cancer.

© 2014 UICC.

In plain English

This prospective study followed 58,279 Dutch men aged 55 to 69 for 17.3 years from 1986. Workplace asbestos exposure was estimated from job histories with a job-exposure matrix, not by fiber type. After adjusting for smoking and other factors, most measures showed no statistically significant increased risk of esophageal, gastric or colorectal cancer. Exceptions mainly involved high exposure, but esophageal adenocarcinoma was also linked to any exposure (hazard ratio 1.54, 95% CI 1.03 to 2.29). Against men never highly exposed (which included lower-exposed men), men with the longest high exposure had hazard ratios of 2.67 (1.11 to 6.44) for gastric cancer, 3.35 (1.33 to 8.44) for gastric non-cardia adenocarcinoma and 2.54 (1.09 to 5.93) for distal colon cancer. Ever highly exposed men, versus never highly exposed, had 2.52 (1.01 to 6.26) for esophageal adenocarcinoma and 2.15 (1.23 to 3.77) for rectal cancer. Several groups had under ten cases. Lower-exposure gastric cancer links lost significance after adjusting for smoking. No statistically significant asbestos-smoking interaction was found. The authors concluded this suggests raised risks after prolonged high exposure.

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: Prospective population-based cohort study analysed with a case-cohort approach (published as a short report)
• Who was studied: 58,279 men from the general population of the Netherlands, aged 55–69 years at enrolment in September 1986, followed for 17.3 years. Women were not included. Analyses included 1,866 subcohort members and 187 esophageal, 486 gastric and 1,724 colorectal cancer cases.
• Exposure: Occupational asbestos exposure, not separated by fiber type. It was estimated by linking self-reported job histories (up to five jobs, until 1986) to the DOMJEM job-exposure matrix. The exposure measures were ever versus never exposed, duration of exposure, cumulative exposure (unit-years), ever versus never highly exposed, and duration of high exposure.
• Main results:
  • Overall esophageal cancer, multivariable-adjusted: no statistically significant results. Ever versus never highly exposed gave HR 2.22 (1.00–4.94), and duration of high exposure per 10 years gave HR 1.45 (1.00–2.10). Both were described as borderline significant.
  • Esophageal adenocarcinoma (EAC): ever versus never highly exposed gave HR 2.52 (1.01–6.26), based on 6 cases in the ever highly exposed group. The association was also significant for other exposure variables, including ever versus never exposed: HR 1.54 (1.03–2.29), based on 48 cases.
  • Overall gastric cancer: the highest tertile of duration of high exposure gave HR 2.67 (1.11–6.44), based on 9 cases. The comparison group was men never highly exposed.
  • Gastric cancer: associations with other (lower-level) exposure measures were significant when adjusting only for age and family history. They mostly disappeared after multivariable adjustment, especially for smoking status.
  • Some short-duration exposure groups had statistically significantly lower hazard ratios. For example, the lowest tertile of duration of exposure gave HR 0.63 (0.42–0.94) for gastric cancer, multivariable-adjusted.
  • Gastric non-cardia adenocarcinoma (GNCA): the highest tertile of duration of high exposure gave HR 3.35 (1.33–8.44), based on 8 cases. The comparison group was men never highly exposed. Gastric cardia adenocarcinoma (GCA) showed no statistically significant associations.
  • Overall colorectal cancer: ever versus never highly exposed gave HR 1.53 (1.00–2.34), described as borderline significant.
  • Highest tertile of duration of high exposure, compared with men never highly exposed: HR 2.19 (1.04–4.62) for total colon cancer (15 cases) and HR 2.54 (1.09–5.93) for distal colon cancer (9 cases).
  • Rectal cancer: ever versus never highly exposed gave HR 2.15 (1.23–3.77), based on 21 cases.
  • Proximal colon cancer: no association or exposure–response relation was statistically significant.
  • No statistically significant additive or multiplicative interaction between asbestos and smoking was found for any cancer. For esophageal cancer, the p for multiplicative interaction was 0.09.
• The authors' conclusion: The authors concluded that the study suggests increased hazard ratios for overall gastric cancer, and possibly also for overall esophageal and colorectal cancer, after (prolonged) exposure to high asbestos levels. The same applied to EAC, GNCA, total colon, distal colon and rectal cancer. They added that adjusting for smoking may be relevant when studying gastric cancer and GNCA.
• Limitations the authors state:
  • The exposure assessment, based on a job-exposure matrix, possibly involved non-differential misclassification, which would bias results towards no effect.
  • Job-exposure matrices, especially DOMJEM, classify jobs with lower and more variable asbestos exposure less accurately than jobs with known high exposure. This could produce false-negative results.
  • Potential confounders, notably smoking, were more than weakly correlated with asbestos exposure, as the gastric cancer results showed.
  • Most hazard ratios were only marginally significant to begin with.
  • Sample sizes for the interaction analyses were small, especially for esophageal cancer.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Colon cancer, Stomach cancer, Throat and laryngeal cancer.

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Colorectal Cancer, Cohort Study, Adenocarcinoma, Stomach Cancer.

Related studies

• Occupational exposures and risk of esophageal and gastric cardia cancers among male Swedish construction workers — C. Jansson, A.L. Johansson, et al. (2005)
• Occupational asbestos exposure and risk of pleural mesothelioma, lung cancer, and laryngeal cancer in the prospective Netherlands cohort study — N.S. Offermans, R. Vermeulen, et al. (2014)
• Airborne exposures and risk of gastric cancer: a prospective cohort study — K. Sjödahl, C. Jansson, et al. (2007)
• Occupational exposures and risk of oesophageal cancer by histological type: a case-control study in eastern Spain — M. Santibañez, J. Vioque, et al. (2008)
• Comparison of expert and job-exposure matrix-based retrospective exposure assessment of occupational carcinogens in The Netherlands Cohort Study — N.S. Offermans, R. Vermeulen, et al. (2012)
• Occupational Exposures and Esophageal Cancer: Prog Study — A. Gressier, G. Gourier, et al. (2022)

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