Authors's response: Pleural mesothelioma and occupational and non-occupational asbestos exposure: a case-control study with quantitative risk assessment

Our plain-English summary of Authors's response: Pleural mesothelioma and occupational and non-occupational asbestos exposure: a case-control study with quantitative risk assessment, by D. Ferrante, D. Mirabelli, S. Tunesi, et al (Occupational and Environmental Medicine, 2016).

The study

• Authors: D. Ferrante, D. Mirabelli, S. Tunesi, B. Terracini, C. Magnani
• Journal: Occupational and Environmental Medicine
• Published: 2016;73(10):713-4
• Type of article: Letter, Comment
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Summary of the article

In this letter, the authors of a published case-control study of pleural mesothelioma and occupational and non-occupational asbestos exposure in Casale Monferrato, Italy, replied to criticisms of that study by Boffetta. They stated that proxy respondents made up 7.2% of controls, not 93% as Boffetta had indicated, and that the exposure-response trend was steeper for direct interviews. They argued that awareness of asbestos-related cancer risks applied to the whole local community, not only to cases. They said that if exposed controls had selectively entered the study, the findings would be biased towards the null. They reported that, after publication, they had found no differences in demographic and social characteristics between respondents and non-respondents (paper in preparation). They defended their expert-based retrospective exposure assessment, while acknowledging that it was not a perfect method and was difficult to reproduce and document. They cited a systematic review for the Second Italian Consensus Conference on Pleural Mesothelioma. That review identified eight cohort, three nested and two population-based case-control studies on cumulative exposure, and seven case-control studies on lung burden, and consistently showed mesothelioma risk proportional to cumulative exposure. In their own data, a model with cumulative exposure fitted better than a model with latency (AIC 501.3 vs 557.5). A model with both was unstable but showed the same trend. They explained that reference categories differed between models in supplementary tables S1 and S2, so those estimates should not be compared directly. They also noted that environmental exposure could be a negative confounder. They confirmed their conclusion that cumulative exposure is important for mesothelioma risk and said this supports asbestos bans and remediation.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

This letter is the authors' reply to criticisms by Boffetta of their earlier case-control study of pleural mesothelioma and occupational and non-occupational asbestos exposure in Casale Monferrato, Italy. It reports no new study. The authors stated that 7.2% of controls, not 93%, had proxy respondents, and that the exposure-response trend was steeper for direct interviews. After publication they compared respondents and non-respondents and observed no demographic or social differences (paper in preparation). They acknowledged that expert-based exposure assessment is not a perfect method and is difficult to reproduce and document. A model using cumulative exposure fitted better than one using latency (AIC 501.3 versus 557.5). A model with both was unstable and not presented, but showed the same trend with cumulative exposure. They cited their earlier systematic review, which found risk consistently proportional to cumulative exposure. The authors concluded that their results on the importance of cumulative exposure stand and support asbestos bans and remediation. Two authors disclosed acting as expert witnesses for the public prosecutor in criminal trials on asbestos-related cancers.

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: Letter to the editor: the authors' response to a published critique of their own earlier case-control study. It contains no new study.
• Who was studied: Pleural mesothelioma cases and individually matched controls from the authors' earlier Casale Monferrato (Italy) case-control study. Numbers are not given in this letter.
• Exposure: Occupational, residential (environmental) and familial (domestic) asbestos exposure, reconstructed from life histories and rated by blind expert evaluation. It was expressed as cumulative exposure in fibre/mL-years. Fiber types are not named in this letter.
• Main results:
  • Among controls, the proportion answered by proxy respondents was 7.2%, not 93% as stated by Boffetta.
  • The exposure-response trend was steeper for direct interviews than for proxy interviews.
  • After publication, the authors compared respondents and non-respondents and observed no differences in demographic and social characteristics. The analysis is not yet published.
  • The model with cumulative exposure fitted better than the model with latency: AIC 501.3 versus 557.5.
  • A model including both latency and cumulative exposure was unstable and was not presented, but it showed the same trend of odds ratios with cumulative exposure.
  • Across panels of supplementary table S1 that counted exposures by different 'probability' ratings, the odds ratios were not statistically different and showed the same trend.
  • In preliminary analyses excluding participants with environmental or domestic exposure, occupational exposure showed the same trend with mesothelioma. The authors noted that environmental exposure can be a negative confounder of occupational exposure if not adequately adjusted for.
  • In the two comparable models of table 2, odds ratios and trends were consistent. The only difference was in the open-ended group of 10 or more fibre/mL-years.
  • The authors cited their earlier systematic review for the Second Italian Consensus Conference on Pleural Mesothelioma, not this letter. That review covered eight cohort, three nested and two population-based case-control studies, plus seven lung-burden case-control studies, and found risk consistently proportional to cumulative exposure.
• The authors' conclusion: The authors concluded that they confirm their results on the importance of cumulative exposure for mesothelioma risk. They stated that these results support reducing asbestos exposure through a ban and effective remediation of asbestos in place.
• Limitations the authors state:
  • Expert-based retrospective exposure assessment is not a perfect methodology and is difficult to reproduce and document.
  • Because matching was not used in the analyses, it was impossible to truncate controls' exposure histories as the critic suggested. The authors argued that any resulting overestimate of controls' exposure would make the odds ratios underestimated.

Topics

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Asbestos Exposure, Case-Control Study, Casale Monferrato, Systematic Review, Cumulative Exposure, Mesothelioma, Latency.

Related studies

• Pleural mesothelioma and asbestos exposure: a case-control study with quantitative risk assessment-response to Marsh and Benson's letter — D. Ferrante, D. Mirabelli, et al. (2017)
• Pleural mesothelioma and occupational and non-occupational asbestos exposure: a case-control study with quantitative risk assessment — D. Ferrante, D. Mirabelli, et al. (2016)
• Response to: 'Pleural mesothelioma and occupational and non-occupational asbestos exposure: a case-control study with quantitative risk assessment' by Ferrante et al — G.M. Marsh, S.M. Benson (2017)
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