Dark under the Lamp: Neglected Biological Pollutants in the Environment Are Closely Linked to Lung Cancer

Our plain-English summary of Dark under the Lamp: Neglected Biological Pollutants in the Environment Are Closely Linked to Lung Cancer, by D. Wang, B.C. Chan, B. Zhang, et al (International Journal of Molecular Sciences, 2024).

The study

• Authors: D. Wang, B.C. Chan, B. Zhang, K.C. Wong, L.L. Kan, C.K. Wong
• Journal: International Journal of Molecular Sciences
• Published: 2024;25(6)
• Type of article: Review
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Environmental pollutants are closely linked to lung cancer. The different types of environmental pollutants can be classified as chemical, physical, and biological. The roles of common chemical and physical pollutants such as PM2.5, smoking, radon, asbestos, and formaldehyde in lung cancer have been extensively studied. Notably, the worldwide COVID-19 pandemic raised awareness of the strong link between biological pollution and human health. Allergens such as house dust mites and pollen, as well as bacteria and viruses, are common biological pollutants. A few biological pollutants have been reported to promote lung cancer via inducing inflammatory cytokines secretion, such as IL-1β, IL-6, and TGF-β, as well as suppressing immunosurveillance by upregulating regulatory T (Treg) cells while dampening the function of CD8+ T cells and dendritic cells. However, the correlation between common biological hazards, such as SARS-CoV-2, human immunodeficiency viruses, Helicobacter pylori, and house dust mites, and lung cancer is not fully elucidated, and the underlying mechanisms are still unclear. Moreover, the majority of studies that have been performed in lung cancer and biological carcinogens were not based on the perspective of biological pollutants, which has challenged the systematicity and coherence in the field of biological pollutants in lung cancer. Here, in addition to reviewing the recent progress made in investigating the roles of allergens, viruses, and bacteria in lung cancer, we summarized the potential mechanisms underlying biological pollutants in lung cancer. Our narrative review can shed light on understanding the significance of biological pollutants in lung cancer, as well as inspire and broaden research ideas on lung cancer etiology.

In plain English

This article was a narrative review of research on biological pollutants (viruses, bacteria and allergens) and lung cancer. It did not study asbestos, naming it only twice, in lists of extensively studied pollutants and of exposures found carcinogenic to humans. The authors searched the Web of Science database for 2003 to 2023. Air pollution was the most frequent keyword in research on environmental pollution and lung cancer, and biological pollution had not been emphasized. A PubMed search on 14 December 2023 of titles and abstracts for 'biological pollution' or 'biological pollutant' with 'lung cancer' retrieved zero results, which the authors took to show such research is rare. The review summarized earlier studies of viruses (including SARS-CoV-2, HIV, HPV and EBV), bacteria (including H. pylori and Mycobacterium tuberculosis), house dust mites and pollen. The authors wrote that these links were not fully elucidated and that the proposed mechanisms all involved chronic inflammation. They concluded that biological pollutants could contribute to lung cancer through chronic inflammation and that more research was needed. They named the paucity of publications as a limitation.

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: Narrative review, with the authors' own bibliometric keyword analysis of the Web of Science database and a PubMed search
• Who was studied: No people were studied. The authors reviewed published literature and searched the Web of Science Core Collection for articles and reviews on environmental pollution and lung cancer from 2003 to 2023. The number of records is not given in the text.
• Exposure: Biological pollutants: viruses, common allergens and bacteria. Asbestos was not reviewed. It was named only twice: in the abstract, in a list of chemical and physical pollutants whose roles in lung cancer the authors said were extensively studied, and in the introduction, in a list of exposures found to be carcinogenic to humans.
• Main results:
  • In the authors' bibliometric analysis, air pollution was the most frequent keyword in environmental pollution and lung cancer research over the previous 20 years.
  • In the bibliometric analysis, the main research topic shifted over time from chemical pollution to air pollution.
  • In the bibliometric analysis, the effect of biological pollution on lung cancer had not been emphasized in the previous 20 years of environmental pollution research.
  • A PubMed search of titles and abstracts for the terms 'biological pollution' or 'biological pollutant' together with 'lung cancer' returned zero results on 14 December 2023. The authors took this to indicate that lung cancer research on the concept of biological pollution is rare.
  • The authors' interpretation of the zero-result PubMed search.
  • Across the reviewed studies, the authors found that the reported mechanisms linking biological contaminants to lung cancer all involved chronic inflammation.
  • The authors reported that some reviewed studies challenged the idea that HPV infection is a risk factor for lung cancer.
• The authors' conclusion: The authors concluded that exposure to major biological pollutants such as viruses, pathogenic bacteria and allergens can worsen inflammation in the body and lead to chronic inflammation, which could contribute to increased lung cancer incidence and malignancy. They also concluded that more research is urgently needed.
• Limitations the authors state:
  • Because few publications exist, the links between specific biological pollutants and lung cancer are unclear, and the mechanisms have not been fully worked out.
  • A bibliometric analysis could not be used to identify the main bacteria associated with lung cancer, because suitable search keywords were hard to define.

Topics

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

Medical terms in this study, explained in our Lexicon: Lung Cancer, Cytokine, Etiology.

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