Incidence of lung cancer by histological type among asbestos cement workers in Denmark

Our plain-English summary of Incidence of lung cancer by histological type among asbestos cement workers in Denmark, by E. Raffn, E. Lynge, B. Korsgaard (British Journal of Industrial Medicine, 1993).

The study

• Authors: E. Raffn, E. Lynge, B. Korsgaard
• Journal: British Journal of Industrial Medicine
• Published: 1993;50(1):85-9
• Cited by: 32 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objective: A significant twofold increased risk of lung cancer was found among 8000 men employed in the Danish asbestos cement industry between 1928 and 1984. The histological pattern of 104 lung cancer cases was studied with the aim of evaluating a relation between specific morphological types, duration of employment, and time since first employment.

Methods: Age, sex, and calendar time specific incidence of morphological subtypes of lung cancer (adenocarcinoma, squamous cell carcinoma, anaplastic carcinoma, and unspecified malignant tumour) for all Danish men were computed from 1943 to 1984, from data routinely collected by the Danish Cancer Registry. Person-years of observation were counted from 15 years after the date of first employment until date of diagnosis of cancer, death, emigration, or the end of follow up on 31 December 1984. Expected numbers of cases were computed by applying person-years at risk to the appropriate incidence rates. Observed numbers were distributed accordingly and the relative risk calculated.

Results: The relative risk for adenocarcinoma was 3.31 (observed (O) 24, expected (E) 7.26), for squamous cell carcinoma 1.67 (O, 37, E, 22.12), for anaplastic carcinoma 1.58 (O, 23, E, 14.53), and for unspecified malignant tumour 1.57 (O, 18, E, 11.46). An increased risk by duration of employment and time since first employment was most pronounced for adenocarcinoma.

Conclusion: The link between adenocarcinoma and asbestos was confirmed in this, the first study of risk of lung cancer by histological category based on incident cancer cases for a whole population during a 50 year period.

In plain English

The authors followed men employed from 1928 to 1984 at Dansk Eternit in Aalborg, Denmark's only asbestos cement factory. The factory used chrysotile, plus amosite from 1946 and small amounts of crocidolite from 1952 to 1968. They compared lung cancers of each cell type with the numbers expected from rates among all Danish men, counting from 15 years after first employment. Of 162 lung cancers found from 1943 to 1984, 104 were analysed. Relative risk was raised for adenocarcinoma (3.31, 95% confidence interval 2.12 to 4.92; 24 cases) and for squamous cell carcinoma (1.67, 1.18 to 2.31; 37 cases). For anaplastic carcinoma (1.58) and unspecified tumours (1.57) the results were at the borderline of statistical significance. The authors reported a rising risk with longer employment and longer time since first employment only for adenocarcinoma: 2.32, 3.60 and 3.92 for under one, one to four, and five or more years employed. Smoking among the employees had never been studied. The authors concluded that their results indicate asbestos relates to adenocarcinoma differently than to squamous cell and anaplastic carcinoma.

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: Cohort study of cancer incidence, comparing observed lung cancer cases by histological type with the numbers expected from national incidence rates for Danish men
• Who was studied: All persons employed 1928 to 1984 at Dansk Eternit, the only asbestos cement factory in Denmark (Aalborg): 7996 men and 584 women traced. Lung cancers among the men were followed from 1943 to 1984, giving 162 cases. After excluding 3 men with irregular working periods and 55 cases diagnosed within 15 years of first employment, 104 cases were analysed.
• Exposure: Work in asbestos cement manufacture. Chrysotile was the only fibre until 1946, when amosite was introduced. Small amounts of crocidolite were used between 1952 and 1968. Estimated concentrations were 50 to 800 fibres per ml in 1948 and 10 to 100 fibres per ml in 1957. In 1973, 41% of measurements were above 2.0 fibres per ml.
• Main results:
  • Adenocarcinoma among the 104 cases analysed with 15 years latency: 24 observed, relative risk (O/E) 3.31, 95% CI 2.12 to 4.92, significantly increased
  • Squamous cell carcinoma: 37 observed, relative risk 1.67, 95% CI 1.18 to 2.31, significantly increased
  • Anaplastic carcinoma (relative risk 1.58) and histologically unspecified malignant tumour (relative risk 1.57) were at the borderline of statistical significance
  • By duration of employment, the relative risk for adenocarcinoma was 2.32 for less than one year, 3.60 for one to four years and 3.92 for five years or more
  • By duration of employment (less than one, one to four, five or more years), relative risks were 2.18, 0.96 and 1.57 for squamous cell carcinoma and 1.56, 0.98 and 1.75 for anaplastic carcinoma
  • By time since first employment (15 to 24, 25 to 34, 35 or more years), relative risks for adenocarcinoma were 1.91, 4.72 and 4.79. Anaplastic carcinoma rose from 1.27 to 2.46, then fell to 1.01 at 35 years or more.
  • The authors stated that an increasing relative risk by duration of employment and time since first employment was found only for adenocarcinoma
  • To check for bias from the source of pathology material, the authors compared necropsy frequency. It was not higher in Aalborg than in the rest of Denmark.
  • A 1973 cross-sectional study found 95% present or former smokers among cement workers in Aalborg, compared with 92% among men in Aalborg in general
• The authors' conclusion: The authors concluded that their results indicate the relation between asbestos exposure and adenocarcinoma of the lung differs from the relation between asbestos exposure and squamous cell and anaplastic carcinoma. In the abstract they state that the link between adenocarcinoma and asbestos was confirmed.
• Limitations the authors state:
  • Smoking habits of the factory's employees were never studied. Only a separate 1973 survey of cement workers in Aalborg was available.

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, Asbestos-Cement, Adenocarcinoma, Squamous Cell Carcinoma, Carcinoma, Cancer Registry, Incidence, Relative Risk.

Related studies

• Lung cancer in asbestos cement workers in Denmark — E. Raffn, E. Villadsen, et al. (1996)
• An attempt to use the WHO typing in the histological classification of lung carcinomas — A. Reinilä, K. Dammert (1974)
• Incidence of cancer and mortality among employees in the asbestos cement industry in Denmark — E. Raffn, E. Lynge, et al. (1989)
• Colorectal cancer in asbestos cement workers in Denmark — E. Raffn, E. Villadsen, et al. (1996)
• Occupational exposures and risk of oesophageal cancer by histological type: a case-control study in eastern Spain — M. Santibañez, J. Vioque, et al. (2008)
• Occupational exposures and risk of stomach cancer by histological type — M. Santibañez, J. Alguacil, et al. (2012)

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