Proportion of lung cancers due to occupational exposure

Our plain-English summary of Proportion of lung cancers due to occupational exposure, by U. Pastorino, F. Berrino, A. Gervasio, et al (International Journal of Cancer, 1984).

The study

• Authors: U. Pastorino, F. Berrino, A. Gervasio, V. Pesenti, E. Riboli, P. Crosignani
• Journal: International Journal of Cancer
• Published: 1984;33(2):231-7
• Cited by: 58 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 001667).

Abstract

The proportions of male lung cancers due to occupational exposure and, respectively, to cigarette smoking in a highly industrialized area of Northern Italy were estimated in a population-based case-control study in 1976-9. Two hundred and four out of the 211 lung cancer cases and 351 controls sampled from the source population were questioned about their occupational and smoking histories. On the basis of the occupational history each subject was classified as probably exposed (+), possibly exposed (?), or unexposed (-) to one or more of the chemicals known to be carcinogenic for the human lung, namely asbestos, polycyclic aromatic hydrocarbons, arsenic, nickel and chromium compounds, BCME, CMME and vinyl chloride. Upon stratification by cigarette smoking, contrasting the occupationally exposed subjects, whether certainly or uncertainly defined, with the unexposed ones, the RR for lung cancer was 2.1 and the occupational etiologic fraction was 0.33 (95% confidence interval 0.19-0.47). The tobacco etiologic fraction was 0.81, while the two exposures together accounted for 89% of the total burden of incident cases. If 33% of all male lung cancers were of occupational aetiology, then this alone would represent 5% of all cancer deaths.

In plain English

This 1976 to 1979 population-based case-control study in an industrial area of Lombardy, Italy, estimated what share of male lung cancers was attributable to workplace carcinogens and to smoking. It included 204 men with lung cancer and 351 control men. Three authors, blind to case status, classified each man as probably, possibly or not exposed to asbestos (any type), polycyclic aromatic hydrocarbons, or other listed chemicals. After adjustment for smoking, probably and possibly exposed men, combined, had a lung cancer risk ratio of about 2 versus unexposed men. The authors estimated that removing occupational exposure could theoretically have prevented 33.0% of cases (95% confidence interval 19.1 to 46.9), and removing tobacco 81% (95% confidence interval 68.8 to 93.2). Asbestos-exposed men (alone or with other hazards) had a roughly derived adjusted risk ratio of 2.34 versus men exposed to none of the studied carcinogens, and 1.79 versus all men not exposed to asbestos. The authors concluded that one-third to two-fifths of male lung cancers there were due to occupation. They noted that the study was not designed to separate individual hazards.

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: Population-based case-control study
• Who was studied: Men living in Health Administration Unit No. 9 of the Lombardy region, Northern Italy (total population 128,000 in 20 towns), 1976-1979. There were 211 incident lung cancer cases. Controls were drawn at random from the male electoral rolls and 366 were enrolled. After 7 cases and 15 controls could not be reached, 204 cases and 351 controls were analyzed.
• Exposure: Occupational exposure, inferred from job histories, to asbestos (any type), polycyclic aromatic hydrocarbons (PAH), and a group made up of chromium, nickel and arsenic compounds, BCME, CMME and vinyl chloride. Each was coded as certain or highly probable (+), uncertain (?) or absent (-). Cigarette smoking was also assessed.
• Main results:
  • Occupationally exposed men, certain (+) and uncertain (?) combined, had a lung cancer risk ratio of about 2 compared with unexposed men, whatever adjustment was used (crude 2.07; 2.10 adjusted for age and cigarettes per day).
  • Overall occupational etiologic fraction (share of cases theoretically preventable by eliminating occupational exposure): 33.0% (95% CI 19.1 to 46.9). Among the exposed it was 51.4%.
  • Share of incident cases preventable by eliminating the effect of tobacco: 81% (95% CI 68.8 to 93.2).
  • Tobacco and occupational exposure together: 88.8% (95% CI 73.6 to 96.2) of incident cases theoretically preventable by eliminating both.
  • Restricting the analysis to the 115 patients alive at interview gave a risk ratio of 1.84 for occupational exposure.
  • Men exposed to asbestos, alone or with other hazards, compared with men not exposed to any of the studied carcinogens, after adjustment and roughly derived from Table V: risk ratio 2.34. Compared with all men not exposed to asbestos, the risk ratio was 1.79.
• The authors' conclusion: The authors concluded that occupation accounted for one-third to two-fifths of male lung cancers in the area (compatible with 20 to 50%). They judged this higher than other researchers' estimates. They stated that 33% of male lung cancers would account for 5% of all cancer deaths in the study area.
• Limitations the authors state:
  • Over half of the cases had died before interview, so their information came from next of kin. This was true for only about 10% of controls.
  • The broad exposure criteria probably misclassified some unexposed men as exposed, so the authors considered the reported risk ratios underestimates.
  • The study was not designed to separate the effects of single occupational hazards.
  • Some potential confounders could not be accounted for: diet, radon in dwellings, passive smoking, filtered or low-tar cigarettes, and depth of inhalation.
  • Coding rules were partly arbitrary. For example, no asbestos exposure was assumed in building work before the Second World War, though the authors say such exposure cannot be excluded.

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, Occupational Exposure, Case-Control Study, Occupational History, Carcinogenic, Population Attributable Fraction (PAF), confidence interval.

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