Talc exposure and risk of stomach cancer: Systematic review and meta-analysis of occupational cohort studies

Our plain-English summary of Talc exposure and risk of stomach cancer: Systematic review and meta-analysis of occupational cohort studies, by C.J. Chang, Y.K. Tu, P.C. Chen, et al (Journal of the Formosan Medical Association = Taiwan Yi Zhi, 2020).

The study

• Authors: C.J. Chang, Y.K. Tu, P.C. Chen, H.Y. Yang
• Journal: Journal of the Formosan Medical Association = Taiwan Yi Zhi
• Published: 2020;119(4):781-792
• Type of article: Meta-analysis, Systematic review
• Cited by: 17 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background/purpose: Talc powder is widely used in various industries, but the carcinogenic effects associated with talc are not well understood. The objective of this study was to estimate the risk of stomach cancer after occupational talc exposure.

Methods: We conducted a meta-analysis was performed to calculate the meta-relative risk (mRR) of stomach cancer. We searched the MEDLINE, EMBASE, CNKI and Wanfang Data databases for publications prior to January 1, 2017 using talc, cancer, and mortality as the search terms. Only cohort studies with occupational talc exposure and stomach cancer statistics were included.

Results: All pooled analyses were based on random-effects models. We selected 13 observational studies (12 publications) for the meta-analysis, and heterogeneity was observed among studies. Workers exposed to all forms of talc had a significantly increased mRR of 1.21 (95% CI: 1.03-1.42, p = 0.02) for stomach cancer. Workers exposed to talc not containing asbestiform fibers also had an increased mRR of 1.26 (95% CI: 0.97-1.63, p = 0.09).

Conclusion: The available data showed a positive association between occupational talc exposure and risk of stomach cancer. The association between talc not containing asbestiform fibers and risk of stomach cancer was not significant. Further epidemiological studies are required to evaluate the safety of talc.

Copyright © 2018. Published by Elsevier B.V.

In plain English

This was a systematic review and meta-analysis that pooled earlier studies of workers exposed to talc on the job. The authors searched English- and Chinese-language databases for cohort studies published before January 1, 2017. They combined 13 worker groups from 12 publications, including talc miners and millers and workers in industries that use talc, such as rubber, paper, printing and pottery. Across all forms of talc, the pooled relative risk of stomach cancer, compared with the general population, was 1.21 (95% CI 1.03 to 1.42). For talc not containing asbestiform fibers the figure was 1.26 (95% CI 0.97 to 1.63). For talc contaminated with asbestos or asbestiform fibers it was 1.17 (95% CI 0.93 to 1.46). Neither subgroup result was statistically significant, and the two subgroups did not differ significantly. Leaving out either of two large studies made the overall result non-significant. The authors concluded that occupational talc exposure was associated with an increased risk of stomach cancer, but they could not determine whether this was due to asbestos contamination. They noted many co-exposures, incomplete smoking data and a lack of quantitative exposure data.

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: Systematic review and meta-analysis of occupational cohort studies (random-effects models)
• Who was studied: 13 cohorts of talc-exposed workers from 12 publications in English or Chinese, published before January 1, 2017. The cohorts were from Russia, Italy, China, the USA, Germany, Norway, Austria, France and a multinational pulp and paper study. Six cohorts were from talc-producing companies (mining and milling) and seven from user industries (rubber, paper, printing, pottery, plastering).
• Exposure: Occupational talc exposure. The authors classed talc as 'containing asbestiform fibers' if it was fibrous, asbestiform or interlaced with asbestos, and otherwise as 'not containing asbestiform fibers'. Six cohorts were exposed to talc not containing asbestiform fibers. Workers also had co-exposures such as asbestos, silica, quartz, radon, nitrosamines and carbon black.
• Main results:
  • Among all workers exposed to talc, the pooled meta-relative risk (mRR) of stomach cancer was 1.21 (95% CI 1.03 to 1.42, p = 0.02).
  • Among workers exposed to talc not containing asbestiform fibers, the mRR was 1.26 (95% CI 0.97 to 1.63, p = 0.09), which was not statistically significant.
  • Among cohorts exposed to talc contaminated with asbestos or asbestiform fibers, the mRR was 1.17 (95% CI 0.93 to 1.46, p = 0.18).
  • The difference between the two talc-type subgroups was not significant (p = 0.68).
  • Excluding the Stern et al. cohort or the McLean et al. cohort made the overall mRR non-significant.
  • By region (excluding the multinational study), the mRR was 1.02 (95% CI 0.86 to 1.22) in Europe, 1.49 (95% CI 1.28 to 1.74) in North America and 1.37 (95% CI 0.95 to 1.98) in Asia.
  • The authors found no evidence of publication bias (Egger's test p = 0.35).
  • Pooled across all cohorts, the mRR for death from all causes was 1.06 (95% CI 0.96 to 1.17).
• The authors' conclusion: The authors concluded that occupational talc exposure is associated with an increased risk of stomach cancer. They could not draw the same conclusion for talc not containing asbestiform fibers, and could not determine whether the increased risk was due to asbestos contamination.
• Limitations the authors state:
  • The number of workers exposed to talc not containing asbestiform fibers was limited.
  • Smoking data were not available for all cohorts.
  • Other stomach cancer risk factors, such as Helicobacter pylori infection, could not be included.
  • The lack of quantitative talc exposure data prevented the authors from identifying a dose-response relationship.
  • Workers had more co-exposures than the authors could properly handle.
  • Because there were no previous reviews on this topic, the authors advised interpreting their findings skeptically.

Topics

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

Medical terms in this study, explained in our Lexicon: Talc, Stomach Cancer, Systematic Review, Meta-Analysis, Carcinogenic, Relative Risk, Asbestiform.

Related studies

• Stomach Cancer and Exposure to Talc Powder without Asbestos via Chinese Herbal Medicine: A Population-Based Cohort Study — C.J. Chang, Y.H. Yang, et al. (2019)
• Occupational Exposure to Talc Increases the Risk of Lung Cancer: A Meta-Analysis of Occupational Cohort Studies — C.J. Chang, Y.K. Tu, et al. (2017)
• Exposure to nitrosamines, carbon black, asbestos, and talc and mortality from stomach, lung, and laryngeal cancer in a cohort of rubber workers — K. Straif, U. Keil, et al. (2000)
• Talc-coated rice as a risk factor for stomach cancer — G.N. Stemmermann, L.N. Kolonel (1978)
• Stomach cancer and occupational exposure to asbestos: a meta-analysis of occupational cohort studies — L. Fortunato, L. Rushton (2015)
• Talc-treated rice and Japanese stomach cancer — R.R. Merliss (1971)

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