Prostate Cancer and Asbestos: A Systematic Review and Meta-Analysis

Our plain-English summary of Prostate Cancer and Asbestos: A Systematic Review and Meta-Analysis, by F. Dutheil, L. Zaragoza-Civale, B. Pereira, et al (The Permanente Journal, 2020).

The study

• Authors: F. Dutheil, L. Zaragoza-Civale, B. Pereira, M. Mermillod, J.S. Baker, J. Schmidt, F. Moustafa, V. Navel
• Journal: The Permanente Journal
• Published: 2020;24
• Type of article: Meta-analysis, Systematic review
• Cited by: 15 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Introduction: Asbestos-related diseases and cancers represent a major public health concern.

Objective: To conduct a systematic review and meta-analysis to demonstrate that asbestos exposure increases the risk of prostate cancer.

Methods: The PubMed, Cochrane Library, Embase, and ScienceDirect databases were searched using the keywords (prostate cancer OR prostatic neoplasm) AND (asbestos* OR crocidolite* OR chrysotile* OR amphibole* OR amosite*). To be included, articles needed to describe our primary outcome: Risk of prostate cancer after any asbestos exposure.

Results: We included 33 studies with 15,687 cases of prostate cancer among 723,566 individuals. Asbestos exposure increased the risk of prostate cancer (effect size = 1.10, 95% confidence interval [CI] = 1.05-1.15). When we considered mode of absorption, respiratory inhalation increased the risk of prostate cancer (1.10, 95% CI = 1.05-1.14). Both environmental and occupational exposure increased the risk of prostate cancer (1.25, 95% CI = 1.01-1.48; and 1.07, 1.04-1.10, respectively). For type of fibers, the amosite group had an increased risk of prostate cancer (1.12, 95% CI = 1.05-1.19), and there were no significant results for the chrysotile/crocidolite group. The risk was higher in Europe (1.12, 95% CI = 1.05-1.19), without significant results in other continents.

Discussion: Asbestos exposure seems to increase prostate cancer risk. The main mechanism of absorption was respiratory. Both environmental and occupational asbestos exposure were linked to increased risk of prostate cancer.

Conclusion: Patients who were exposed to asbestos should possibly be encouraged to complete more frequent prostate cancer screening.

In plain English

This was a systematic review and meta-analysis, a study that pools the results of earlier studies. The authors searched four databases for studies reporting prostate cancer cases or deaths after any asbestos exposure. They included 33 studies, mostly cohort studies, covering 723,566 men. Most studies concerned workplace exposure, such as mining, shipyards, firefighting, and the asbestos and construction industries. Five concerned environmental exposure. Across studies, asbestos exposure was associated with a higher risk of prostate cancer (effect size 1.10, 95% CI 1.05-1.15). The pooled figure was 1.25 (95% CI 1.01-1.48) for environmental exposure and 1.07 (1.04-1.10) for occupational exposure. The amosite group showed a raised risk (1.12, 95% CI 1.05-1.19). The result for the chrysotile/crocidolite group was not statistically significant. A raised risk was found in Europe, but there was no statistically significant result for North America, Asia or Oceania. The authors concluded that asbestos exposure could potentially increase prostate cancer risk, and that prospective studies are needed to confirm this. They noted that the included studies suffered from confounding bias, that only one study concerned swallowed asbestos, and that the amosite group also included chrysotile/crocidolite.

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 33 published studies: 32 cohort studies and 1 case-control study
• Who was studied: 33 studies from Europe, Asia, North America and Oceania found by searching PubMed, Cochrane Library, Embase and ScienceDirect on September 1, 2019; 723,566 men in total
• Exposure: Any asbestos exposure. 28 studies concerned work exposure: miners, shipbreaking and shipyard workers, construction and asbestos industry workers, firefighters, and one study with occupation unspecified. 5 studies concerned environmental exposure: drinking asbestos-contaminated water, residential asbestos insulation, and childhood residence near a crocidolite mine. 32 studies concerned inhalation and 1 concerned oral ingestion.
• Main results:
  • Overall, across the 30 studies in the meta-analysis, asbestos exposure was associated with an increased risk of prostate cancer: effect size 1.10, 95% CI 1.05-1.15, I2 11.4%
  • After excluding studies not evenly distributed in the funnel plots, the overall risk was 1.12 (95% CI 1.07-1.18)
  • The oral ingestion result (from 1 study) showed no evidence of increased risk: effect size 1.70, 95% CI 0.90-2.50. For respiratory inhalation the text reports 1.10, 95% CI 1.05-1.15.
  • Environmental exposure: effect size 1.25 (95% CI 1.01-1.48). Occupational exposure: 1.07 (95% CI 1.04-1.10).
  • The amosite group showed an increased risk: effect size 1.12, 95% CI 1.05-1.19
  • No evidence of increased risk for the chrysotile/crocidolite group (1.13, 95% CI 0.98-1.28) or the nonspecified-fiber group (1.05, 95% CI 0.90-1.21)
  • Increased risk in Europe (1.12, 95% CI 1.05-1.19). No evidence of increased risk in North America (1.11, 95% CI 0.94-1.28), Asia (1.09, 95% CI 0.82-1.36) or Oceania (1.28, 95% CI 0.99-1.58).
  • In meta-regression, factors including sex, age, cohort size, lifestyle, toxic exposures, follow-up duration, type of absorption, type of exposure, fiber type, type of risk and geographic zone did not influence the risk of prostate cancer
• The authors' conclusion: The authors concluded that asbestos exposure could potentially lead to an increased risk of prostate cancer, and that prospective studies are warranted to confirm this
• Limitations the authors state:
  • The included studies suffered from confounding bias
  • Only one study concerned oral ingestion, so results for oral absorption are inconclusive
  • The amosite group also included chrysotile/crocidolite, and the share of each fiber type was not reported, so no firm conclusions can be drawn about specific fiber types
  • Differences in prostate cancer screening between countries may have biased incidence
  • Differences in how studies measured exposure prevented analysis by amount of exposure
  • Some studies did not control for smoking and alcohol
  • Some ecological studies assigned environmental exposure by address at the time of the study, so exposure may have been misclassified
  • No studies gave details on use of personal protective equipment

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Systematic Review, Meta-Analysis, Asbestos Exposure, Neoplasm, Crocidolite, Chrysotile, Amphibole Group, Amosite.

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