Asbestos exposure and malignant lymphoma: a multicenter case-control study in Germany and Italy

Our plain-English summary of Asbestos exposure and malignant lymphoma: a multicenter case-control study in Germany and Italy, by A. Seidler, N. Becker, A. Nieters, et al (International Archives of Occupational and Environmental Health, 2010).

The study

• Authors: A. Seidler, N. Becker, A. Nieters, R. Arhelger, B. Mester, K. Rossnagel, E. Deeg, G. Elsner, M. Melis, S. Sesler, G. Avataneo, M. Meloni, P. Cocco
• Journal: International Archives of Occupational and Environmental Health
• Published: 2010;83(5):563-70
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Aims: To analyze the relationship between asbestos exposure and malignant lymphoma in a multicenter case-control study conducted in Germany and Italy according to a common core protocol.

Methods: Male and female patients with malignant lymphoma (n = 1,034) between 18 and 80 years of age were prospectively recruited in six study areas in Germany (Ludwigshafen/Upper Palatinate, Heidelberg/Rhine-Neckar-County, Würzburg/Lower Frankonia, Hamburg, Bielefeld/East Westphalia, and Munich) and in two study areas in Sardinia, Italy (Cagliari and Nuoro provinces). A total of 1,173 population control subjects were drawn from population registers. In a structured personal interview, we elicited a complete occupational history, including every occupational period that lasted at least 1 year. On the basis of job task-specific supplementary questionnaires, trained experts assessed the exposure to asbestos. As a measure of cumulative asbestos exposure on a time by intensity scale, fiber-years were calculated. 12 cases (1.2%) and 12 control subjects (1.0%) had a cumulative asbestos exposure of more than 2.6 fiber-years (highest exposure category according to the 90th percentile of exposed control subjects). Odds ratios (OR) and 95% confidence intervals (CI) were calculated using unconditional logistic regression analysis adjusted for age, sex and study region. Patients with specific lymphoma sub-entities were additionally compared with the entire control group.

Results: We observed no statistically significant association between cumulative asbestos exposure and the risk of any lymphoma subtype. An elevated risk was found for the association between exposure to more than 2.6 fiber-years and multiple myeloma (OR = 6.0; 95% CI 1.4-25.1); however, numbers were small (n = 3 cases, all of them from Italy; n = 12 control subjects).

Conclusions: Our study does not support an association between asbestos exposure and risk of malignant lymphoma.

In plain English

This population-based case-control study pooled the German and Italian (Sardinian) parts of the European EPILYMPH project. It compared 1,034 adults aged 18 to 80 with newly diagnosed malignant lymphoma with 1,173 population controls. Trained experts assessed asbestos exposure from work histories and calculated cumulative fiber-years. Fiber types were not specified. For all lymphomas combined, the authors found no association. In the highest category, above 2.6 fiber-years, there were 12 cases (1.2%) and 12 controls (1.0%), with an odds ratio of 1.3 (95% CI 0.6 to 2.9). For multiple myeloma, the text reports an odds ratio of 6.0 (95% CI 1.4 to 25.1) above 2.6 fiber-years, based on 3 cases, all from Italy. The table shows this figure for the Italian data, and 4.1 (1.1 to 15.5) for both countries pooled. The authors said this might be a chance finding. They noted low statistical power and low participation among German controls (44%). The authors concluded they did not find convincing evidence of an association between asbestos exposure and malignant lymphoma.

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; pooled analysis of the German and Italian parts of the European EPILYMPH project
• Who was studied: 1,034 newly diagnosed lymphoma cases aged 18 to 80. Of these, 710 were in six German regions (participation 87.4%) and 324 were in Cagliari and Nuoro provinces, Sardinia, Italy (participation 91%). There were 1,173 population controls drawn from population registers: 710 German (participation 44%) and 463 Italian (participation 69.5%). Recruitment years are not given in the text.
• Exposure: Occupational asbestos exposure, fiber type not specified. Industrial hygienists and occupational physicians, blind to case or control status, rated it from job histories and job-task questionnaires. They calculated cumulative fiber-years, grouped as 0, more than 0 to 0.3, more than 0.3 to 2.6, and more than 2.6 fiber-years.
• Main results:
  • All lymphomas combined, both countries pooled: no association. Above 2.6 fiber-years there were 12 cases (1.2%) and 12 controls (1.0%), with an odds ratio of 1.3 (95% CI 0.6 to 2.9).
  • German sub-study, all lymphomas, above 2.6 fiber-years: a raised odds ratio that was not statistically significant, 3.0 (95% CI 0.6 to 15.0), based on 6 cases and 2 controls.
  • By major subtype (Hodgkin lymphoma, B-cell NHL, T-cell NHL), there were no significantly elevated risks. German B-cell NHL above 2.6 fiber-years had an odds ratio of 3.0 (95% CI 0.6 to 16.0), based on 5 cases and 2 controls.
  • Multiple myeloma above 2.6 fiber-years: the text reports an odds ratio of 6.0 (95% CI 1.4 to 25.1). All 3 cases in this category came from the Italian sub-study.
  • In Table 4, the pooled German and Italian figure for multiple myeloma above 2.6 fiber-years was an odds ratio of 4.1 (95% CI 1.1 to 15.5), based on 3 cases (3.0%) and 12 controls (1.0%).
  • The authors noted that the multiple myeloma association had not been reported before and might be a chance finding.
  • When only probable or certain exposure was counted, all lymphomas above 2.6 fiber-years had an odds ratio of 1.0 (95% CI 0.4 to 2.5), based on 8 cases and 11 controls.
  • Table 4 also shows follicular lymphoma at more than 0 to 0.3 fiber-years (pooled) with an odds ratio of 2.2 (95% CI 1.1 to 4.5), based on 11 cases. The authors did not discuss this figure.
• The authors' conclusion: The authors concluded that they did not find convincing evidence of an association between asbestos exposure and risk of malignant lymphoma.
• Limitations the authors state:
  • The study had low power to detect slight risk elevations: 80% power to detect an odds ratio of 2.8, but only 41% for an odds ratio of 2.0. Power was further limited for lymphoma subgroups.
  • Exposure assessment based on job descriptions can still misclassify exposure.
  • Asbestos exposure was rare among the relatively young study subjects.
  • Low response among German controls may have caused selection bias. The authors said that results based on the Italian part alone did not substantially change, except for the increased multiple myeloma risk.
  • Pooling studies with different matching methods could introduce bias. In a sensitivity analysis using conditional regression, odds ratios remained nearly unchanged.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Case-Control Study, Occupational History, Fiber Year, Odds Ratio, confidence interval, Myeloma.

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