Cancer incidence in a cohort of asbestos-exposed workers undergoing health surveillance

Our plain-English summary of Cancer incidence in a cohort of asbestos-exposed workers undergoing health surveillance, by F. Barbiero, T. Zanin, F.E. Pisa, et al (International Archives of Occupational and Environmental Health, 2018).

The study

• Authors: F. Barbiero, T. Zanin, F.E. Pisa, A. Casetta, V. Rosolen, M. Giangreco, C. Negro, M. Bovenzi, F. Barbone
• Journal: International Archives of Occupational and Environmental Health
• Published: 2018;91(7):831-841
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: To compare a local cohort of 2488 men occupationally exposed to asbestos and enrolled in a public health surveillance program with the 1995-2009 cancer incidence of the general population of Friuli Venezia Giulia (FVG) region, Northeast Italy, we conducted a historical cohort study.

Methods: Standardized incidence ratios (SIRs), with 95% confidence interval (95% CI), for specific cancer sites were estimated in the cohort and in subgroups of workers employed in shipbuilding between 1974 and 1994. For internal comparisons, we calculated incidence rate ratios (IRRs) for all cancers, lung cancer and mesothelioma, by level of exposure to asbestos and sector of employment adjusted for smoking habits and age at start of follow-up.

Results: Among cohort members the SIR was 8.82 (95% CI 5.95-12.61) for mesothelioma and 1.61 (95% CI 1.26-2.04) for lung cancer. In subgroup analyses, the SIR for lung cancer in subjects hired in shipbuilding between 1974 and 1984 was 2.09 (95% CI 1.32-3.13). In the overall cohort, a borderline increased incidence was also found for stomach cancer (SIR = 1.53 95% CI 0.96-2.31). Internal comparisons within the cohort show that among men with high asbestos exposure level the relative risk was almost threefold for lung cancer (IRR = 2.94 95% CI 1.01-8.57).

Conclusions: This cohort experienced an excess in the incidence of both mesothelioma and lung cancer, showing increasing incidence rates at higher level of asbestos exposure. For lung cancer, the relative incidence was highest among workers hired in shipbuilding between 1974 and 1984.

In plain English

This historical cohort study followed 2,488 men with past work exposure to asbestos who had joined a voluntary public health surveillance program at a clinic in Monfalcone, in the Friuli Venezia Giulia (FVG) region of northeast Italy. About 70% had worked in shipbuilding. Cancers diagnosed from 1995 to 2009 were found through the regional cancer registry and compared with rates in the general FVG population. The men had 30 cases of mesothelioma against 3.40 expected (standardized incidence ratio 8.82, 95% CI 5.95 to 12.61) and 66 cases of lung cancer (ratio 1.61, 95% CI 1.26 to 2.04). The increase for stomach cancer was borderline (ratio 1.53, 95% CI 0.96 to 2.31). Within the cohort, men rated as highly exposed had almost three times the lung cancer rate of men with low exposure (IRR 2.94, 95% CI 1.01 to 8.57). Smoking was also strongly linked to lung cancer. The authors concluded that mesothelioma and lung cancer incidence rose with intensity of exposure. They noted that follow-up ending in 2009 may be too short given the long latency of these cancers.

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: Historical cohort study comparing the cohort with the general regional population (external comparison), plus internal comparisons within the cohort using Poisson regression
• Who was studied: 2488 men with prior occupational exposure to asbestos, identified at the Monfalcone public health surveillance clinic in Friuli Venezia Giulia, Northeast Italy, between 1991 and 2008, and followed for cancer from 1995 to 2009. About 70% were shipyard workers.
• Exposure: Past occupational asbestos exposure in shipbuilding (70.4%), metalworking, electrical utilities, insulation and other sectors. Fiber types were not specified. Exposure intensity was rated low, moderate or high from work history using job-exposure matrices from the literature.
• Main results:
  • All cancers in the whole cohort: 337 observed versus 297.33 expected, SIR 1.13 (95% CI 1.02 to 1.26). The authors say this was largely explained by respiratory cancers.
  • Lung cancer in the whole cohort: 66 cases, SIR 1.61 (95% CI 1.26 to 2.04) compared with the FVG population
  • Mesothelioma in the whole cohort: 30 cases observed versus 3.40 expected, SIR 8.82 (95% CI 5.95 to 12.61)
  • Stomach cancer in the whole cohort showed a borderline increase, SIR 1.53 (95% CI 0.96 to 2.31)
  • Bladder cancer incidence in the cohort was significantly lower than expected
  • In the comparison with the general population, a higher level of asbestos exposure went with higher SIRs for all cancers, lung cancer and mesothelioma
  • SIRs for all cancers and lung cancer were particularly high among shipbuilding workers hired between 1974 and 1984
  • Mesothelioma SIRs were very high in all hiring-period groups, ranging from 7.72 to 9.56
  • Within the cohort, men with high exposure had almost three times the lung cancer rate of men with low exposure: IRR 2.94 (95% CI 1.01 to 8.57)
  • For lung cancer within the cohort, the IRR was 4.74 for current smokers and 2.36 for ex-smokers, both compared with never smokers
  • Current smokers in the cohort had an increased risk of all cancers: IRR 1.38 (95% CI 1.09 to 1.75)
  • Lung cancer was associated with intensity of asbestos exposure but not with its duration
  • For mesothelioma there was no statistically significant association with smoking. After full adjustment, there was no increased risk for shipbuilding compared with other sectors.
• The authors' conclusion: The authors concluded that the cohort had a moderate excess of all cancers, a strong excess of mesothelioma and a moderate excess of lung cancer. Both mesothelioma and lung cancer incidence increased with higher intensity of exposure. Relative lung cancer incidence was highest among shipbuilding workers hired in 1974 to 1984. They called for evidence on whether prevention is effective for formerly exposed workers.
• Limitations the authors state:
  • FVG has the highest mesothelioma incidence in Italy, so using it as the comparison population may have underestimated the excess risk
  • About 400 subjects were excluded because they could not be linked to the regional health database, which may have biased results in either direction
  • Smoking and exposure intensity were not assessed quantitatively, and cumulative dose was not considered, so exposure may be misclassified
  • Too few non-pleural mesotheliomas occurred for separate analysis by site. Pleural mesothelioma made up 83.0% (25 cases).
  • Follow-up ended in 2009 and may be incomplete given latency that can exceed 40 years
  • Exposures other than asbestos were not assessed, which limits interpretation of the stomach cancer finding
  • The high mesothelioma risk among workers hired in 1985 to 1994 may partly reflect misrecorded dates of first exposure

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Cohort Study, Standardized Incidence Ratio (SIR), confidence interval, Incidence, Lung Cancer, Mesothelioma, Habit, Stomach Cancer.

Related studies

• Mortality in a cohort of asbestos-exposed workers undergoing health surveillance — F. Barbiero, T. Zanin, et al. (2018)
• Mesothelioma incidence surveillance systems and claims for workers' compensation. Epidemiological evidence and prospects for an integrated framework — A. Marinaccio, A. Scarselli, et al. (2012)
• Malignant mesothelioma due to non-occupational asbestos exposure from the Italian national surveillance system (ReNaM): epidemiology and public health issues — A. Marinaccio, A. Binazzi, et al. (2015)
• Cancer mortality and incidence of mesothelioma in a cohort of wives of asbestos workers in Casale Monferrato, Italy — D. Ferrante, M. Bertolotti, et al. (2007)
• Cancer incidence among Swedish pulp and paper mill workers: a cohort study of sulphate and sulphite mills — E. Andersson, H. Westberg, et al. (2013)
• Impact of low-dose computed tomography screening on lung cancer mortality among asbestos-exposed workers — F. Barbone, F. Barbiero, et al. (2018)

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