Cancer incidence and mortality among Finnish asbestos sprayers and in asbestosis and silicosis patients

Our plain-English summary of Cancer incidence and mortality among Finnish asbestos sprayers and in asbestosis and silicosis patients, by P. Oksa, E. Pukkala, A. Karjalainen, et al (American Journal of Industrial Medicine, 1997).

The study

• Authors: P. Oksa, E. Pukkala, A. Karjalainen, A. Ojajärvi, M.S. Huuskonen
• Journal: American Journal of Industrial Medicine
• Published: 1997;31(6):693-8
• Cited by: 33 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Cohorts of Finnish asbestos sprayers and of asbestosis and silicosis patients were followed for cancer with the aid of the Finnish Cancer Registry in the period 1967-1994. Compared with the cancer incidence of the total Finnish population, asbestos sprayers had an increased risk for total cancer (standardized incidence ratio [SIR] 6.7, 95% confidence interval [95% CI] 4.2-10); lung cancer (SIR 17.95% CI 8.2-31); and mesothelioma (SIR 263, 95% CI 85-614). The SIR of the asbestosis patients was 3.7 (95% CI 2.8-5.0) for all sites, 10 (95% CI 6.9-14) for lung cancer, and 65 (95% CI 13-188) for mesothelioma. The silicosis patients also had significantly high SIR values for all sites (1.5, 95% CI 1.0-2.1) and lung cancer (2.7, 95% CI 1.5-4.5). The values for the SIR and the standardized mortality ratio for all sites and lung cancer were very similar, and therefore it seems that both are reliable indicators of the occurrence of occupational cancer. It was concluded that pneumoconioses patients and asbestos-exposed workers have a markedly elevated risk for cancer. Asbestos-induced occupational cancers are not only diseases of the elderly, since the relative risk is high also for middle-aged people.

In plain English

This Finnish registry study followed 129 asbestos sprayers, 118 asbestosis patients and 163 silicosis patients, all men, for cancer from 1967 to 1994, comparing them with the whole Finnish population. The authors report crocidolite was the main asbestos sprayed. Sprayers had 22 cancers against 3.3 expected (standardized incidence ratio, SIR, 6.7; 95% confidence interval, CI, 4.2 to 10). These included five mesotheliomas, two peritoneal (SIR 263 for all five, CI 85 to 614), and ten lung cancers (SIR 17, CI 8.2 to 31). Asbestosis patients had 47 cancers against 13 expected (SIR 3.7, CI 2.8 to 5.0), including three pleural mesotheliomas and 33 lung cancers (SIR 10, CI 6.9 to 14). Silicosis patients had 31 cancers against 21 expected (SIR 1.5, CI 1.0 to 2.1) and 15 lung cancers (SIR 2.7, CI 1.5 to 4.5). No lung cancers occurred among nonsmokers. The authors found the incidence and mortality ratios for all cancers and lung cancer very similar. They concluded these groups had a markedly elevated cancer risk. Smoking data existed for only 60 sprayers.

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 using record linkage to the Finnish Cancer Registry and national death data, comparing observed cancers and deaths with expected numbers from the Finnish population (standardized incidence and mortality ratios)
• Who was studied: Finnish asbestos sprayers and patients with asbestosis or silicosis, followed 1967 to 1994. The male cohorts analyzed were 129 sprayers, 118 asbestosis patients and 163 silicosis patients. There were also 4, 10 and 7 women, respectively. The asbestosis and silicosis cohorts were formed in 1977 to 1985 at the Finnish Institute of Occupational Health.
• Exposure: Asbestos spraying (performed in Finland 1955 to 1976), mainly with crocidolite. For the 60 examined sprayers, mean exposure was three years (range 0.2 to 13). Asbestosis patients included insulation workers, anthophyllite quarry workers, chrysotile-exposed asbestos cement workers and sprayers, with a mean exposure of 21 years. Silicosis patients (stone, mine, quarry, foundry, construction, glass, clay and pottery workers) had a mean exposure of 24 years.
• Main results:
  • Male asbestos sprayers had 22 cancers against 3.3 expected (SIR 6.7, 95% CI 4.2 to 10).
  • Male sprayers had five mesotheliomas, two of them peritoneal; the SIR for all five mesotheliomas was 263 (95% CI 85 to 614). They also had ten lung cancers (SIR 17, 95% CI 8.2 to 31).
  • Male asbestosis patients had 47 cancers against 13 expected (SIR 3.7, 95% CI 2.8 to 5.0). These included three mesotheliomas, all pleural (SIR 65, 95% CI 13 to 188), and 33 lung cancers (SIR 10, 95% CI 6.9 to 14).
  • Male silicosis patients had 31 cancers against 21 expected (SIR 1.5, 95% CI 1.0 to 2.1). They had 15 lung cancers (SIR 2.7, 95% CI 1.5 to 4.5) and no mesotheliomas.
  • There were no lung cancer cases among nonsmokers in any cohort.
  • The relative risk of lung cancer was highest among middle-aged asbestos-exposed men.
  • Among male sprayers and asbestosis patients, standardized mortality ratios for all causes, all cancers, lung cancer and respiratory diseases were significantly high. Among silicosis patients, only respiratory disease mortality was significantly high.
  • Among the women with asbestosis there were two cases of lung cancer (SIR 33, 95% CI 4.0 to 118).
• The authors' conclusion: The authors concluded that pneumoconiosis patients and asbestos-exposed workers have a markedly elevated cancer risk. They also concluded that asbestos-induced occupational cancers are not only diseases of the elderly. They reported that the standardized incidence and mortality ratios for all cancers and lung cancer were very similar.
• Limitations the authors state:
  • Data on smoking and exposure duration were available only for the 60 sprayers who attended a 1987 health examination.
  • No smoking-specific reference data were available, so smoking-specific risks were calculated against the general Finnish population.
  • Among silicosis patients, the numbers of specific lung cancer types were too small for further analysis.
  • The excess of other cancers among sprayers rested on a small number of cases.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

Medical terms in this study, explained in our Lexicon: Silicosis, Cancer Registry, Standardized Incidence Ratio (SIR), confidence interval, Lung Cancer, Mesothelioma, standardized mortality ratio (SMR), Relative Risk.

Related studies

• Silicosis, asbestosis, and cancer of the lung — W.C. Hueper (1955)
• Serum oncoproteins and growth factors in asbestosis and silicosis patients — P.W. Brandt-Rauf, S. Smith, et al. (1992)
• Past exposure to asbestos and combustion products and incidence of cancer among Finnish locomotive drivers — P. Nokso-Koivisto, E. Pukkala (1994)
• Mechanisms in the pathogenesis of asbestosis and silicosis — B.T. Mossman, A. Churg (1998)
• Asbestosis and silicosis — G.R. Wagner (1997)
• Current concepts about the pathogenesis of silicosis and asbestosis — R.D. deShazo (1982)

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