Multiple factors in carcinogenesis

Our plain-English summary of Multiple factors in carcinogenesis, by S.S. Epstein (Environmental Health Perspectives, 1974).

The study

• Author: S.S. Epstein
• Journal: Environmental Health Perspectives
• Published: 1974;9:331-3
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 002350).

In plain English

This 1974 article was a short commentary that reported no new data. Commenting on a conference, the author stated that asbestos is a carcinogen. The author argued that asbestos deliberately added to foodstuffs through processing breached a US law, the Delaney Amendment, and called the question of asbestos in water a complex legal matter. The author wrote that the literature made clear that smoking enhances bronchogenic (airway) cancer after occupational asbestos exposure. Two explanations were offered. Smoking might simply weaken the airways' mucus-clearing defenses, or particles and smoke carcinogens might interact more directly. The author said toxicology had lagged behind epidemiology on such combined effects. The author also described other researchers' animal experiments. In hamster lungs, benzpyrene or iron oxide alone gave no tumors, but the mixture gave a high incidence of bronchial cancers. In rats, either benzpyrene or sulfur dioxide alone gave essentially no bronchial carcinomas, while both together gave bronchial cancers and some forestomach cancers. The author proposed laboratory studies of whether asbestos in tissues changes how other carcinogens act, and whether chemicals make tissues more sensitive to asbestos.

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: Commentary (opinion piece with no original data)
• Who was studied: No study population; the author commented on discussion at a conference and on published literature
• Exposure: Asbestos in general (no fiber type named): occupational exposure combined with cigarette smoking, and asbestos in foodstuffs, drugs and water
• Main results:
  • Not a finding of this article: the author stated, based on conference discussion and the literature, that smoking enhances the incidence of bronchogenic cancer after occupational asbestos exposure
  • The author proposed one possible non-specific explanation: smoking inhibits the airways' mucociliary defenses
  • The author proposed a possible specific explanation: inhaled particles may interact chemically with carcinogens in cigarette smoke
  • The author's opinion: toxicology had lagged behind epidemiology in studying multiple factors
  • Described from other researchers' work (Saffiotti and colleagues), not this article: mixtures of benzpyrene and iron oxide placed in hamster lungs produced a high incidence of bronchogenic squamous carcinomas, while each alone did not produce tumors
  • Described from other researchers' work (Laskin's group), not this article: rats exposed to sulfur dioxide alone or benzpyrene alone got, to all intents and purposes, no bronchial carcinomas, while rats exposed to both got squamous bronchial cancers and some squamous carcinomas of the forestomach
  • The author argued that asbestos deliberately introduced into foodstuffs by processing contravenes the Delaney Amendment, and called the question of asbestos in water a complex legal matter
• The authors' conclusion: The author proposed laboratory studies of whether asbestos in tissues increases the activity of other carcinogens, and whether chemicals sensitize tissues to asbestos. The author suggested such information could complement the existing epidemiological data on multiple factors in asbestos carcinogenesis.

Topics

Medical terms in this study, explained in our Lexicon: Carcinogenesis.

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• Chronic infections and inflammatory processes as cancer risk factors: possible role of nitric oxide in carcinogenesis — H. Ohshima, H. Bartsch (1994)
• Reactive oxygen species, chromosome mutation, and cancer: possible role of clastogenic factors in carcinogenesis — I. Emerit (1994)
• Environmental factors as regulators and effectors of multistep carcinogenesis — T. Minamoto, M. Mai, et al. (1999)
• The enigma of beta-carotene in carcinogenesis: what can be learned from animal studies — R.M. Russell (2004)

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