Incidence of bronchial carcinoma in shipyard workers with pleural plaques

Our plain-English summary of Incidence of bronchial carcinoma in shipyard workers with pleural plaques, by J.R. Edge (Annals of the New York Academy of Sciences, 1979).

The study

• Author: J.R. Edge
• Journal: Annals of the New York Academy of Sciences
• Published: 1979;330:289-94
• Cited by: 24 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. 001022).

Summary of the article

This study asked whether men with pleural plaques have an increased risk of dying from bronchial carcinoma. The subjects were 429 men from Barrow-in-Furness, England, mostly shipyard workers, who had radiologic evidence of pleural plaques and whose first radiographs were taken between 1964 and 1971. They were compared with 429 controls from Carlisle, where there was no known industrial asbestos exposure. Controls were matched by age, sex and date of first radiograph and had no plaques. No one in either group had radiologic pulmonary fibrosis. Most of the men were over 60. Deaths were traced through national and local records. Three subjects and eight controls could not be traced.

There were 127 deaths among the men with plaques (30%) and 74 among the controls (17.2%) (p < 0.001). Bronchial carcinoma caused 19 deaths among the men with plaques and 4 among the controls (p < 0.01). Mesothelioma caused 23 deaths among the men with plaques and none among the controls. Smoking histories were not available. Deaths from ischemic heart disease and chronic bronchitis were similar in the two groups. Men drawn from hospital or clinic sources had a higher proportion of carcinoma deaths, which the author took as a sign of bias. After excluding six men who already had symptoms or suggestive radiographs at entry, the excess (13 versus 4) was of doubtful significance (p < 0.05). In an analysis against national rates, carcinoma deaths after 6 years were twice the expected number. The author concluded that men with pleural plaques carry a twofold risk of bronchial carcinoma and that continued follow-up is needed.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

The author compared 429 men with pleural plaques on chest X-rays from Barrow-in-Furness, England, whose first X-rays were taken between 1964 and 1971, with 429 men from Carlisle, a city with no known industrial asbestos exposure. The Carlisle men were matched by age, sex and date of first X-ray and had no plaques. No man in either group had X-ray signs of lung fibrosis. The plaque group had 53 more deaths than the controls. These included 19 deaths from bronchial carcinoma (a lung cancer) against 4, and 23 mesotheliomas against none. Some plaque cases came from hospitals or clinics, and the author found this introduced bias. Six men who died of bronchial carcinoma already had symptoms or suspicious X-ray changes when they entered the study. Without them, 13 deaths against 4 was an excess the author called of doubtful significance. Smoking histories were not available. Many deaths happened in the first two years of follow-up. Compared with national figures, the author concluded that men with plaques had a twofold risk of dying of bronchial carcinoma, but said longer follow-up was needed before a final conclusion.

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 comparison study following mortality of men with pleural plaques against men without plaques from another city. The author stated a cohort could not be selected. A further analysis compared deaths with national (Registrar General) figures.
• Who was studied: 429 men with radiologic pleural plaques from Barrow-in-Furness, England (first radiographs 1964 to 1971), and 429 controls from Carlisle matched by age, sex and date of first radiograph, with no plaques. Neither group had radiologic pulmonary fibrosis. Most were over 60.
• Exposure: Men with plaques worked in a wide variety of occupations. Only joiners, laggers and painters (106 men, 25%) were thought to be continuously exposed to asbestos. Fiber types were not reported. The control city had no known industrial asbestos exposure.
• Main results:
  • There was an excess of 53 deaths in the plaque (Barrow) group compared with controls (p less than 0.001).
  • Deaths from carcinoma of the bronchus: 19 in the plaque group versus 4 in controls (p less than 0.01).
  • Mesothelioma: 23 deaths in the plaque group, none in controls.
  • Among plaque men found on routine radiographs, 6 (2.6%) died of bronchial carcinoma. Among those from the clinic series, 13 (6.6%) did. The author took this as a sign of bias.
  • Six men who died of bronchial carcinoma already had symptoms or suggestive X-ray changes at entry. After excluding them, 13 deaths versus 4 in controls was described as an excess of doubtful significance (p less than 0.05).
  • In the analysis against national figures (407 men), there were 16 bronchial carcinoma deaths: 8 in the first 2 years, 2 in the next 4 years and 6 after that. After 6 years, bronchial carcinoma deaths were twice the expected figure.
  • In the same analysis, there were 17 mesotheliomas: 10 in the first 2 years, 5 in the next 4 years and 2 after that.
  • Excluding the first 2 years, there were 7 mesothelioma deaths in 2637 man-years of observation, about 1 case per 377 man-years.
• The authors' conclusion: The author concluded that men with pleural plaques carry a twofold risk of dying of carcinoma of the bronchus compared with the general population. Because of the long latent period, continued follow-up would be needed before a final conclusion.
• Limitations the authors state:
  • A cohort could not be selected; the plaque group was all such men known to the author.
  • No direct smoking histories were available. The author used similar death counts from ischemic heart disease and chronic bronchitis to suggest smoking did not differ greatly between groups.
  • Including subjects from hospital or clinic sources introduced bias, since some were already ill at entry.
  • Because of the long latent period, follow-up was not long enough for a final conclusion.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Pleural plaques and thickening, Shipyards and maritime work.

Medical terms in this study, explained in our Lexicon: Carcinoma, Pleural Plaques, Asbestos Exposure, Pulmonary Fibrosis, Mesothelioma.

Related studies

• Prevalence of radiographic abnormalities among Northern California shipyard workers — P.L. Polakoff, B.R. Horn, et al. (1979)
• Mesothelioma incidence in a Dutch shipyard — J. Stumphius (1979)
• Mortality among shipyard workers in Genoa, Italy — R. Puntoni, M. Vercelli, et al. (1979)
• Pleural plaques and respiratory function — B. Järvholm, A. Sandén (1986)
• Asbestosis, pulmonary symptoms and functional impairment in shipyard workers — K.H. Kilburn, R. Warshaw, et al. (1985)
• Lung cancer prevalence among shipyard workers — W.J. Nicholson, R. Lilis, et al. (1980)

Browse more research in Annals of the New York Academy of Sciences, or return to medical research.