Localized pleural plaques and lung cancer

Our plain-English summary of Localized pleural plaques and lung cancer, by T. Partanen, M. Nurminen, A. Zitting, et al (American Journal of Industrial Medicine, 1992).

The study

• Authors: T. Partanen, M. Nurminen, A. Zitting, H. Koskinen, M. Wiikeri, K. Ahlman
• Journal: American Journal of Industrial Medicine
• Published: 1992;22(2):185-92
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

In a mass chest radiography survey conducted in 1971 for 7,986 residents of three Finnish communities, 604 subjects (7.6%) with pleural plaques but not other asbestos-related radiographic signs were identified. The same number of referents, each individually matched to each plaque carrier on sex, birth year, and community, was selected from among persons in the same source population with no pleural plaques. The two groups were followed for investigation of incidence of lung cancer during 1972-1989. Twenty-eight of those with plaques and 25 referents contracted lung cancer (crude conditional RR = 1.1; CL95 = 0.7, 1.9). The application of the proportional hazards model, with adjustment for sex, age, and residence, resulted in a hazard ratio of 1.1 (CL = 0.6, 1.8). The risk ratio estimate may be biased; hence, the result is inconclusive in regard to the predictive assessment of lung cancer risk among carriers of pleural plaques.

In plain English

This Finnish study used a 1971 tuberculosis chest X-ray screening of 7,986 residents of three communities. One was rural Tuusniemi, where anthophyllite asbestos was mined and processed. The other two were Helsinki suburbs, one of which had an asbestos board plant. The X-rays showed pleural plaques, without other asbestos-related signs, in 604 people. Each was matched to a person without plaques of the same sex, birth year and community. Cancer registry records for 1972 to 1989 showed lung cancer in 28 of the 604 plaque carriers and 25 of the 604 comparison subjects, a crude risk ratio of 1.1 (95% confidence limits 0.7 to 1.9). After adjusting for sex, age and residence, the hazard ratio was also 1.1 (0.6 to 1.8). No pleural mesothelioma was recorded in either group. The authors concluded that no excess lung cancer risk was demonstrated among plaque carriers, but that the result was inconclusive. They noted that smoking was not recorded, and that selection and misclassification of plaque status probably biased the result toward no difference.

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: Matched cohort study: people with pleural plaques found at a 1971 mass chest radiography survey and matched referents without plaques, followed through the cancer registry for lung cancer incidence
• Who was studied: 7,986 residents aged 20 to 74 of three Finnish communities (Tuusniemi, Tapanila and Oulunkylä) who attended a 1971 tuberculosis mass screening. Of these, 604 had pleural plaques without other asbestos-related radiographic signs, and each was matched to a referent without plaques on sex, birth year and community (604 referents). Follow-up ran from 1972 to 1989.
• Exposure: Pleural plaques on chest X-ray, taken as a marker of asbestos exposure. The communities differed in exposure: anthophyllite was mined and processed in Tuusniemi until June 1975, and an asbestos board plant operated in Tapanila until 1979. 48 of 363 Tuusniemi plaque carriers and 21 of 363 Tuusniemi referents reported work in the anthophyllite quarry or mill.
• Main results:
  • Lung cancer developed in 28 of the 604 plaque carriers and 25 of the 604 referents, a crude risk ratio of 1.12 (95% confidence limits 0.66, 1.91).
  • In the proportional hazards model adjusted for sex, age and community, the hazard ratio for those with pleural plaques compared with those without was 1.1 (95% confidence limits 0.6, 1.8); Table V gives 1.07 (0.62, 1.83), p = 0.81.
  • Tuusniemi had the highest prevalence of plaques, both in men and women, but the lowest cumulative lung cancer risk among plaque carriers and referents. There were 12 cases among 363 plaque carriers and 9 among 363 referents.
  • In the model, suburban residence was associated with higher lung cancer risk than rural residence (hazard ratio 2.16, 95% confidence limits 1.25, 3.75).
  • No pleural mesothelioma was recorded in either cohort.
  • Among Tuusniemi subjects, 48 (13%) of the 363 plaque carriers and 21 (6%) of the 363 referents reported having worked in the anthophyllite quarry or mill.
• The authors' conclusion: The authors concluded that no excess risk of lung cancer among carriers of pleural plaques was demonstrated. They added that exposure-related selection and biases of unknown magnitude, and partly of unknown direction, make the result inconclusive for predicting lung cancer risk in plaque carriers.
• Limitations the authors state:
  • Smoking habits of the subjects were not recorded.
  • Plaque status was probably misclassified on the small chest radiographs, whose sensitivity and specificity for plaques have not been established. This biases the estimate toward unity by an unknown amount.
  • An unknown number of referents developed pleural plaques during follow-up.
  • Persons with heavy asbestos exposure were probably underrepresented among the plaque carriers, partly because people with other asbestos-related X-ray changes were excluded.
  • Self-selection into the screening may have biased comparisons between communities. Attendance in the Helsinki suburbs was about half that in Tuusniemi, and attendance among former quarry and mill workers was incomplete.

Mines named here

Asbestos mines this study is about. Each mine's page says who ran it, when it worked, and what it produced.

• Paakkila mine, Finland

All asbestos mines

Topics

The National Library of Medicine indexes this study under subjects our site covers: Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Pleural Plaques, Lung Cancer, Hazard Ratio.

Related studies

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• A systematic review of the association between pleural plaques and changes in lung function — L. Kopylev, K.Y. Christensen, et al. (2015)
• Comment on "A systematic review of the association between pleural plaques and changes in lung function" by Kopylev et al (2014) — J.E. Goodman, L.E. Kerper, et al. (2015)
• Authors' response: A systematic review of the association between pleural plaques and changes in lung function — L. Kopylev, K.Y. Christensen, et al. (2015)
• Risk and significance of chest radiograph and pulmonary function abnormalities in an elderly cohort of former nuclear weapons workers — M.A. Mikulski, P.G. Hartley, et al. (2011)
• Asbestos exposure and benign asbestos diseases in 772 formerly exposed workers: dose-response relationships — G. Mastrangelo, M.N. Ballarin, et al. (2009)

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