Airborne exposures and risk of gastric cancer: a prospective cohort study

Our plain-English summary of Airborne exposures and risk of gastric cancer: a prospective cohort study, by K. Sjödahl, C. Jansson, I.A. Bergdahl, et al (International Journal of Cancer, 2007).

The study

• Authors: K. Sjödahl, C. Jansson, I.A. Bergdahl, J. Adami, P. Boffetta, J. Lagergren
• Journal: International Journal of Cancer
• Published: 2007;120(9):2013-8
• Cited by: 42 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

There is an unexplained male predominance among patients with gastric cancer, and many carcinogens are found in male-dominated dusty occupations. However, the relation between occupational exposures and risk of gastric cancer remains unclear. To investigate whether airborne occupational exposures might influence the risk of noncardia gastric cancer, we used a large, prospective cohort study of male Swedish construction workers. These workers were, during the period 1971-1993, regularly invited to health examinations by a nationwide occupational health service organization. Data on job titles and other variables were collected through self-administered questionnaires and forms completed by the health organization's staff. Industrial hygienists assessed 12 specific airborne occupational exposures for 200 job titles. Gastric cancer, death or emigration occurring during follow-up in 1971-2002 were identified by linkage to the Swedish registers of Cancer, Causes of Death and Total Population, respectively. Incidence rate ratios (IRR) and 95% confidence intervals (CI), adjusted for attained age, tobacco smoking, calendar period and body mass, were derived from Cox regression. Among 256,357 cohort members, contributing 5,378,012 person-years at risk, 948 noncardia gastric cancers were identified. Increased risk of this tumor was found among workers exposed to cement dust (IRR 1.5 [95% CI 1.1-2.1]), quartz dust (IRR 1.3 [95% CI 1.0-1.7]) and diesel exhaust (IRR 1.4 [95% CI 1.1-1.9]). Dose-response relations were observed for these exposures. No consistent positive associations were found regarding exposure to asbestos, asphalt fumes, concrete dust, epoxy resins, isocyanates, metal fumes, mineral fibers, organic solvents or wood dust. In conclusion, this study provides some support to the hypothesis that specific airborne exposures increase the risk of noncardia gastric cancer.

(c) 2007 Wiley-Liss, Inc.

In plain English

This prospective study followed 256,357 male Swedish construction workers, first examined between 1971 and 1993, through national registers until 2002. Of these men, 948 developed noncardia gastric cancer, a form of stomach cancer. Industrial hygienists rated each job title for 12 airborne exposures, including asbestos. Only the job held at each man's first examination was used. Results were adjusted for age, smoking, calendar period and body mass. Highly exposed men had higher rates with cement dust (incidence rate ratio 1.5, 95% confidence interval 1.1–2.1), quartz dust (1.3, 1.0–1.7) and diesel exhaust (1.4, 1.1–1.9). For asbestos, the ratios were 0.8 (0.5–1.2) for moderate exposure and 0.7 (0.3–1.4) for high exposure, based on 21 and 7 cases. The authors concluded that the study gives some support to quartz dust, cement dust and diesel exhaust being moderate risk factors. They wrote that their asbestos result argued against a role for airborne asbestos. They noted that exposures were estimated from job titles rather than individual measurement, and that data on duration of exposure and on H. pylori infection were not available.

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 cohort study, analysed with Cox regression adjusted for attained age, calendar period at entry, tobacco smoking status and body mass index
• Who was studied: 256,357 men from the Swedish Construction Workers Cohort, invited to occupational health examinations between 1971 and 1993 and followed through December 31, 2002 (5,378,012 person-years); women were excluded
• Exposure: 12 airborne exposures assigned by a job-exposure matrix built by industrial hygienists from job titles (asbestos, asphalt fumes, cement dust, concrete dust, diesel exhaust, epoxy resins, isocyanates, mineral fibers, metal fumes, organic solvents, quartz dust, wood dust). Each was graded 0 to 5 and grouped as no exposure (0), moderate (0.5 to 1) or high (2 to 5). No asbestos fiber type is specified.
• Main results:
  • 948 incident cases of noncardia gastric cancer were identified in the cohort; the total incidence rate was 17.6 per 100,000 person-years
  • Among highly exposed workers, statistically significantly increased risks were found for cement dust (IRR 1.5, 95% CI 1.1–2.1), quartz dust (IRR 1.3, 95% CI 1.0–1.7) and diesel exhaust (IRR 1.4, 95% CI 1.1–1.9). Combined fumes exposure gave IRR 1.2 (95% CI 1.1–1.4).
  • Asbestos: moderate exposure IRR 0.8 (95% CI 0.5–1.2), 21 cases among 6,971 men; high exposure IRR 0.7 (95% CI 0.3–1.4), 7 cases among 3,514 men. The p value for overall effect was 0.33.
  • No increased risk was detected among workers exposed to asbestos, asphalt fumes, concrete dust, epoxy resins, isocyanates, mineral fibers, metal fumes, organic solvents or wood dust
  • High exposure to organic solvents was associated with a lower risk (IRR 0.6, 95% CI 0.5–0.9)
  • The authors wrote that the lack of association with asbestos in their study argued against an influence of airborne asbestos on gastric cancer
• The authors' conclusion: The authors concluded that this prospective cohort study provides some support to the hypothesis that quartz dust, cement dust and diesel exhaust are moderate risk factors for gastric cancer. They added that these exposures should not substantially influence the overall incidence or the sex difference of this cancer.
• Limitations the authors state:
  • The job-exposure matrix approach allows possible exposure misclassification
  • Lifetime occupational histories and duration of exposure could not be studied; only the job title at the first visit was used
  • Exposures were based solely on job titles, not on each individual's own exposure
  • Data were lacking on some potential confounders, including H. pylori infection
  • The workers most highly exposed to cement dust were mainly storage workers who may be less fit than other workers, so confounding cannot be ruled out

Topics

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

Medical terms in this study, explained in our Lexicon: Stomach Cancer, Cohort Study, Occupational Exposure, Incidence, confidence interval, Dose-response relationship, Mineral Fiber.

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