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

Our plain-English summary of Response to comment on 'The latency period of mesothelioma among a cohort of British asbestos workers (1978-2005)', by G. Frost (British Journal of Cancer, 2014).

The study

• Author: G. Frost
• Journal: British Journal of Cancer
• Published: 2014;111(11):2198-9
• Type of article: Comment
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

In plain English

This is a letter in which the author of a 2013 study on mesothelioma latency (the time from first asbestos exposure to death with mesothelioma) among British asbestos workers replied to criticism from Farioli and colleagues. At their request, the author reanalysed the data using only workers who died with mesothelioma and were first exposed between 1950 and 1969, with follow-up from 1971 to 2005. This did not greatly change the original results. When the model was not adjusted for year of first exposure, three things changed. Women's longer latency (time ratio 1.08, 95% CI 0.96–1.23) was no longer statistically significant. Removal workers had a significantly shorter latency than insulation workers (time ratio 0.93, 0.87–0.98; below 1 means shorter). Latency tended to rise with longer duration of exposure. The author called the duration trend a spurious association. The author also noted that the removal-worker difference ran opposite to what the intensity idea predicts. The author concluded that the original finding stood: no evidence that more intense exposure led to shorter latency. Asbestosis could not be included in this reanalysis.

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 responding to published comments, presenting an additional reanalysis of the author's earlier case-only cohort data using multivariable generalised gamma accelerated failure-time models
• Who was studied: Mesothelioma deaths among British asbestos workers first exposed between 1950 and 1969, followed up 1971 to 2005. Table 1 lists 359 male and 8 female deaths, of whom 220 were first exposed in 1950–1959 and 147 in 1960–1969.
• Exposure: Occupational asbestos exposure. Main occupation was grouped as manufacturing, removal, insulation or other. The models also covered year of first exposure, age at first exposure and duration of exposure. No fiber types are named.
• Main results:
  • Restricting to cases first exposed 1950–1969 and using the full 1971–2005 follow-up did not greatly change the results compared with the original paper
  • Women compared with men: time ratio 1.12 (95% CI 1.01–1.25) when adjusted for year of first exposure, and 1.08 (0.96–1.23) without that adjustment, which was no longer statistically significant
  • Removal workers compared with insulation workers: time ratio 0.98 (0.93–1.03) with adjustment for year of first exposure. Without that adjustment it was 0.93 (0.87–0.98), a statistically significantly shorter latency.
  • Without adjustment for year of first exposure, latency increased with duration of exposure. For example, 30 to 39 years of exposure had a time ratio of 1.27 (1.15–1.42) compared with less than 10 years, against 1.11 (1.01–1.23) in the adjusted model.
  • The author regarded the duration–latency trend as spurious, because latency, year of first exposure and duration of exposure are closely related
  • Workers first exposed in 1960–1969 had a time ratio of 0.86 (0.83–0.90) compared with those first exposed in 1950–1959
  • The latency difference between insulation and removal workers ran opposite to the direction expected if more intense exposure shortened latency
  • When the full cohort (not just mesothelioma deaths) was modelled, the predicted median latency was 115 years. The author considered this uninformative.
• The authors' conclusion: The author concluded that the original conclusion remained unchanged: the study found no evidence that greater intensity of asbestos exposure leads to shorter mesothelioma latency. The author also considered the methodology appropriate and still valid.
• Limitations the authors state:
  • The stratum-specific analysis suggested by the commenters could not be done because there were too few cases in each stratum
  • The reanalysis could not include presence of asbestosis, so the judgement relied only on sex and occupation
  • The estimated median latency is limited by the length of follow-up and would increase as follow-up continues
  • The author acknowledged that the methodology is not perfect

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.

Related studies

• Comment on 'The latency period of mesothelioma among a cohort of British asbestos workers (1978-2005)': methodological problems with case-only survival analysis — D. Consonni, F. Barone-Adesi, et al. (2014)
• Comment on 'The latency period of mesothelioma among a cohort of British asbestos workers (1978-2005)' — D. Mirabelli, D. Zugna (2014)
• Comment on 'The latency period of mesothelioma among a cohort of British asbestos workers (1978-2005)': the effect of left censoring — A. Farioli, S. Mattioli, et al. (2014)
• The latency period of mesothelioma among a cohort of British asbestos workers (1978-2005) — G. Frost (2013)
• Occupational exposures to cosmetic talc and risk of mesothelioma: an updated pooled cohort and statistical power analysis with consideration of latency period — G.M. Marsh, A.M. Ierardi, et al. (2019)
• Letter concerning: Occupational exposures to cosmetic talc and risk of mesothelioma: an updated pooled cohort and statistical power analysis with consideration of latency period by Gary M. Marsh et al. (Inhal Toxicol. 2019 Aug 5:1-11. doi:10.1080/08958378.2019.1645768) — M.M. Finkelstein (2019)

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