Comment on 'The latency period of mesothelioma among a cohort of British asbestos workers (1978-2005)'

Our plain-English summary of Comment on 'The latency period of mesothelioma among a cohort of British asbestos workers (1978-2005)', by D. Mirabelli, D. Zugna (British Journal of Cancer, 2014).

The study

• Authors: D. Mirabelli, D. Zugna
• Journal: British Journal of Cancer
• Published: 2014;111(8):1675
• Type of article: Letter, Comment
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Summary of the article

In this letter, the authors commented on a 2013 paper by Frost. That paper analysed mesothelioma mortality among members of the Great Britain Asbestos Survey (GBAS) using accelerated failure time models and concluded that there was not sufficient evidence that greater intensity of asbestos exposure led to shorter latency. The authors were concerned that the analysis may have been inappropriate and its conclusions unwarranted. Citing Frost's data, they noted that of 94,960 workers entering GBAS between 1978 and 2005, 614 died from mesothelioma and 14,009 from other causes. About 85% were alive at follow-up, and mesothelioma decedents contributed only 9280 of more than 1.6 million person-years. They argued that restricting the analysis to workers who died with mesothelioma, in a setting with substantial censoring and competing mortality, would bias estimates of the cause-specific hazard and cumulative incidence. Drawing on a 1965 paper by Pike and Doll on smoking and age at onset of lung cancer, they also argued that differences in latency between exposure groups would depend largely on historical factors rather than on any biological property of the exposure. They pointed to the fixed observation period, left truncation, and the distinct secular trends of the two main comparison groups, asbestos insulators and asbestos removers. They concluded that the analysis did not find consistent deviations of time ratios from unity because there was no chance for such deviations to occur consistently in the GBAS setting.

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 to the editor reports no new study. Mirabelli and Zugna commented on Frost's 2013 analysis of mesothelioma deaths in the Great Britain Asbestos Survey (GBAS), which found insufficient evidence that more intense asbestos exposure shortened latency. They argued its analysis may have been inappropriate and its conclusions unwarranted. Citing Frost's figures, they noted that of 94960 workers entering GBAS between 1978 and 2005, 614 died from mesothelioma and 14009 from other causes, about 85% were alive at follow-up, and mesothelioma decedents contributed only 9280 of over 1.6 million person-years. Because only mesothelioma decedents were analysed, censoring and competing deaths would, they argued, bias the estimates. Citing Pike and Doll (1965), they argued that when cases come from an observation period fixed by the observer, latency differences between exposure groups depend not on any biological property of exposure but solely or predominantly on historical factors. In GBAS, they noted, insulation work began disappearing as asbestos removal developed. The authors concluded that consistent deviations in time ratios had no chance to occur in GBAS, as in most if not all other cohort studies.

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 commenting on a published cohort analysis (Frost 2013); no new data
• Who was studied: No population of the authors' own. The letter discusses Frost's analysis of the Great Britain Asbestos Survey (GBAS): 94960 workers who entered between 1978 and 2005, of whom 614 died from mesothelioma and 14009 from other causes (figures from Frost's Table 1)
• Exposure: Asbestos exposure among GBAS members; the two main comparison groups in Frost's analysis were asbestos insulators and asbestos removers
• Main results:
  • The authors pointed out that Frost's analysis included only cohort members who died with mesothelioma. They said this departs from the risk-set sampling designs traditionally used for cohort studies.
  • Citing Frost's Table 1, the authors noted that about 85% of GBAS members were alive at follow-up and mesothelioma deaths were 4.4% of all deaths. In their view, this meant both right censoring and substantial competing mortality were present.
  • The authors argued that restricting the analysis to mesothelioma decedents would bias the estimates. They noted that, of more than 1.6 million person-years in the full cohort, mesothelioma decedents contributed only 9280 person-years.
  • Drawing on Pike and Doll (1965), the authors argued that when cases are enrolled within an observation period fixed by the observer and split into exposure groups, differences in latency will not depend on any biological property of the exposure, but solely or predominantly on historical factors. They said this applies to GBAS, which has left truncation and a closing date when about 85% of members were alive.
  • The authors noted that the two main comparison groups, asbestos insulators and asbestos removers, had distinct secular trends: insulation work began to disappear as removal work developed.
• The authors' conclusion: The authors concluded that Frost's analysis did not find consistent deviations of time ratios from unity because there was no chance for such deviations to occur consistently in the GBAS observational setting. They added that the same applies to most if not all other cohort studies.

Topics

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

Medical terms in this study, explained in our Lexicon: Latency, Mesothelioma, Asbestos Exposure, Lung Cancer, Insulator.

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• Response to comment on 'The latency period of mesothelioma among a cohort of British asbestos workers (1978-2005)' — G. Frost (2014)
• The latency period of mesothelioma among a cohort of British asbestos workers (1978-2005) — G. Frost (2013)
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