Environmental factors in causing human cancers: emphasis on tumorigenesis

Our plain-English summary of Environmental factors in causing human cancers: emphasis on tumorigenesis, by U.T. Sankpal, H. Pius, M. Khan, et al (Tumour Biology, 2012).

The study

• Authors: U.T. Sankpal, H. Pius, M. Khan, M.I. Shukoor, P. Maliakal, C.M. Lee, M. Abdelrahim, S.F. Connelly, R. Basha
• Journal: Tumour Biology
• Published: 2012;33(5):1265-74
• Type of article: Review
• Cited by: 49 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The environment and dietary factors play an essential role in the etiology of cancer. Environmental component is implicated in ~80 % of all cancers; however, the causes for certain cancers are still unknown. The potential players associated with various cancers include chemicals, heavy metals, diet, radiation, and smoking. Lifestyle habits such as smoking and alcohol consumption, exposure to certain chemicals (e.g., polycyclic aromatic hydrocarbons, organochlorines), metals and pesticides also pose risk in causing human cancers. Several studies indicated a strong association of lung cancer with the exposure to tobacco products and asbestos. The contribution of excessive sunlight, radiation, occupational exposure (e.g., painting, coal, and certain metals) is also well established in cancer. Smoking, excessive alcohol intake, consumption of an unhealthy diet, and lack of physical activity can act as risk factors for cancer and also impact the prognosis. Even though the environmental disposition is linked to cancer, the level and duration of carcinogen-exposure and associated cellular and biochemical aspects determine the actual risk. Modulations in metabolism and DNA adduct formation are considered central mechanisms in environmental carcinogenesis. This review describes the major environmental contributors in causing cancer with an emphasis on molecular aspects associated with environmental disposition in carcinogenesis.

In plain English

This article was a narrative review, not a new study. The authors described published research on environmental factors linked to human cancer, emphasizing how these agents may cause cancer at the molecular level. Sections covered tobacco and nicotine, dioxins and chlorinated drinking water, polycyclic aromatic hydrocarbons, volatile organic compounds, formaldehyde, benzene, pesticides, metals such as chromium, nickel and arsenic, and mycotoxins such as aflatoxins. The article reported no new data. Asbestos had no section of its own. It was named in the abstract, which said several studies indicated a strong association of lung cancer with exposure to tobacco products and asbestos, and once in the conclusion, which said asbestos and radiation also pose significant risk for cancer. No asbestos studies were discussed, and mesothelioma, asbestosis and fiber types were not mentioned. The authors concluded that a carcinogen's cancer-causing potential depends on the length and intensity of exposure and on individual genetic makeup. They also wrote that more than 30% of cancers could be prevented, mainly by avoiding tobacco exposure, consuming a healthy diet, maintaining physical activity and preventing infections that may cause cancer.

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
• Who was studied: No people were studied. The article reviewed previously published research on environmental causes of human cancer.
• Exposure: Environmental and lifestyle agents in general: tobacco and nicotine, dioxins, chlorinated drinking water, polycyclic aromatic hydrocarbons, volatile organic compounds, formaldehyde, benzene, pesticides, metals (chromium, nickel, arsenic) and mycotoxins. Asbestos was named but not reviewed, and no fiber types were specified.
• Main results:
  • Asbestos was mentioned in the body of the review only once, in the conclusion, where the authors stated that asbestos and radiation also pose significant risk for cancer. No asbestos data or studies were presented.
  • The article's abstract stated that several studies indicated a strong association of lung cancer with exposure to tobacco products and asbestos. The text did not identify or discuss those asbestos studies.
  • Citing the American Cancer Society, the review stated that smoking is responsible for at least 30% of cancer-related deaths.
  • The review described changes in metabolism and DNA adduct formation as central mechanisms in environmental carcinogenesis.
• The authors' conclusion: The authors concluded that the cancer-causing potential of a carcinogen depends on the length and intensity of exposure and on individual genetic makeup. They also concluded that more than 30% of cancers could be prevented, mainly by avoiding exposure to tobacco, consuming a healthy diet, maintaining physical activity and preventing infections that may cause cancer.

Topics

Medical terms in this study, explained in our Lexicon: Tumorigenesis, Etiology, Habit, Lung Cancer, Occupational Exposure, Prognosis, Carcinogenesis.

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• Comments on the Health Effects Institute-Asbestos Research (HEI-AR) report: "Asbestos in public and commercial buildings," with emphasis on risk assessment methods used — T.D. Sterling, C.W. Collett, et al. (1993)
• Quantifying health effects from the combined action of low-level radiation and other environmental agents: can new approaches solve the enigma? — W. Burkart, G.L. Finch, et al. (1997)
• Environmental factors and human health: fibrous and particulate substance-induced immunological disorders and construction of a health-promoting living environment — T. Otsuki, H. Matsuzaki, et al. (2016)

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