Feasibility of a screening programme for lung cancer in former asbestos workers

Our plain-English summary of Feasibility of a screening programme for lung cancer in former asbestos workers, by G. Mastrangelo, M.N. Ballarin, E. Bellini, et al (Occupational Medicine, 2008).

The study

• Authors: G. Mastrangelo, M.N. Ballarin, E. Bellini, R. Bizzotto, F. Zannol, F. Gioffrè, M. Gobbi, G. Tessadri, L. Marchiori, G. Marangi, S. Bozzolan, J.H. Lange, F. Valentini, P. Spolaore
• Journal: Occupational Medicine
• Published: 2008;58(3):175-80
• Cited by: 28 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Low-dose computed tomography (CT) has been found to detect more Stage IA lung cancer than chest x-ray.

Aims: To investigate whether lung cancer screening with CT was effective and acceptable in former asbestos workers.

Methods: CT scanning was carried out following the protocol previously described in the literature. A questionnaire was used to assess cumulative asbestos exposure. An economic analysis was also performed. Informed consent was obtained from all patients.

Results: A total of 1119 male asbestos workers (58% of invited) were examined, of whom 65% were smokers or ex-smokers. Mean age was 57.1 years with mean cumulative exposure to asbestos of 123 fibres/ml x years. Pleural plaques were found in 375 workers (32%), while 338 workers (29%) were included in the radiological follow-up, which led to 25 biopsies (13 of lung, 9 of pleura, 3 of both) and five screen-detected lung cancers (0.4%), one in Stage I. Incidence rate was 149 per 10(5), equal to that in the male general population of similar age. The expenses for diagnosis were 1014 and 244962 Euro per screened subject and screen-detected lung cancer case, respectively.

Conclusions: Screening adherence and frequency of detection were low, while costs and radiation dose were high. In spite of a high cumulative asbestos exposure, lung cancer risk was not increased relative to the general population. The screening programme was not felt to be cost-effective from the perspective of the government as a third-party funding agency.

In plain English

This Italian study tested a one-time low-dose CT lung cancer screening of former asbestos workers in the Veneto Region. Of 2000 former workers invited, 1165 (58%) took part. The analysis covered 1119 men, whose mean estimated cumulative asbestos exposure was 123.0 fibres/ml-years. Scans found pleural plaques in 361 men (32%). Five primary lung cancers were detected, all in current or former smokers, and only one was at Stage I. Assuming three years of follow-up for every worker, the estimated incidence was 149 per 100 000 per year. This was equal to the rate for Veneto men aged 55 to 59 when all workers were treated as aged 57.1 (incidence rate ratio 1.00). Diagnosis cost an estimated €1014 per screened worker and €244 962 per cancer found. The authors suggested that the most exposed workers may have died of lung cancer before the study began. They concluded that uptake and detection were low, costs and radiation dose were high, and the programme was not shown to be cost-effective for government funding. They named the 42% refusal rate as a major limitation.

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: One-time screening programme with low-dose CT, in which each worker was tested once. It was combined with record linkage to hospital discharge records and a cost analysis.
• Who was studied: The starting list was 5379 former asbestos workers in the Veneto Region, Italy, and 2000 of them were invited. 1165 agreed (1129 men and 36 women). After the women and 10 men with missing data were excluded, 1119 male former asbestos workers were analysed. Their mean age at screening was 57.1 years, and 65% were current or former smokers. They were screened between 2000 and 2003 and followed up until July 2005.
• Exposure: Past work in asbestos-cement product manufacture, railway rolling stock fabrication and repair, or insulation work in shipyards or elsewhere. Fibre types were not specified. Exposure was estimated by questionnaire. The means were 17.7 years of exposure, an intensity of 16.7 fibres/ml, and a cumulative exposure of 123.0 fibres/ml-years (SD 221.0).
• Main results:
  • Of the 2000 workers invited, 1165 (58%) agreed to be examined.
  • Among the screened workers, 361 had asbestos pleural plaques (prevalence 32%). The article also reports 242 men with non-calcified lung nodules (prevalence 21%).
  • There were 16 lung biopsies. 5 of them showed lung cancer: 4 primary and 1 secondary. One more primary lung cancer was diagnosed by sputum cytology, giving five screen-detected primary lung cancers.
  • Only one of the five screen-detected lung cancers was found at Stage I (Stage IA).
  • Cumulative incidence of lung cancer was 0.4% among all 1119 screened men and 0.69% among smokers or ex-smokers. All cases were current or former smokers.
  • Lung cancer incidence in the screened men was estimated at 149 per 100 000 per year (5 cases over 1119 times 3 person-years). This rested on the assumption that all 1119 workers were screened in July 2002 and followed up for 3 years until July 2005.
  • The authors treated all screened workers as having the mean age of 57.1 years. On that basis, comparison with the Veneto Tumour Registry rate for men aged 55 to 59 gave an incidence rate ratio of 1.00.
  • In the wider cohort of 4367 former asbestos workers found in the regional register, lung cancer incidence from 1999 to 2005 was 154 per 100 000.
  • No lung cancers were missed after a negative CT, and there were 11 false-positive biopsies. Sensitivity was 100%, specificity 99% and positive predictive value 31%.
  • Estimated cost was €1014 per screened worker.
  • Estimated cost was €244 962 per screen-detected lung cancer, out of an estimated overall cost of €1 224 811.
  • Estimated radiation dose at the first screening round was close to 1000 mSv in total. This was an average of 1 mSv per examined worker and 220 mSv per screen-detected lung cancer, as printed.
  • The authors suggested that the timing of exposure could explain why lung cancer risk was not increased: the most exposed and susceptible workers may have died from lung cancer before the study began.
• The authors' conclusion: The authors concluded that CT screening had low uptake and a low lung cancer detection rate, with high costs in time, money and radiation. Lung cancer incidence in these asbestos workers equalled that of the general male population of the same age. The programme was not demonstrated as cost-effective from the perspective of the government as a third-party funding agency, and it was discontinued.
• Limitations the authors state:
  • 835 (42%) of the invited workers refused to take part, and the reasons for refusing were not known. The authors noted that the similar incidence in the screened workers and the total cohort suggested no major differences in risk factors.

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: Lung Cancer, Low-Dose CT Screening, Stage IA, Chest X-Ray, Asbestos Exposure, Informed Consent, Cumulative Exposure, Pleural Plaques.

Related studies

• Lung cancer risk in past asbestos workers a few decades after exposure cessation and prospects for screening — G. Mastrangelo, G. Marangi, et al. (2016)
• Yield of Low-Dose Computerized Tomography Screening for Lung Cancer in High-Risk Workers: The Case of 7189 US Nuclear Weapons Workers — S.B. Markowitz, A. Manowitz, et al. (2018)
• Asbestos exposure and benign asbestos diseases in 772 formerly exposed workers: dose-response relationships — G. Mastrangelo, M.N. Ballarin, et al. (2009)
• The costs and effects of screening for cancer among asbestos-exposed workers — B.J. McNeil, D.M. Eddy (1982)
• Diagnostic Performance of Ultra-Low-Dose Computed Tomography for Detecting Asbestos-Related Pleuropulmonary Diseases: Prospective Study in a Screening Setting — M. Schaal, F. Severac, et al. (2016)
• Health surveillance for former asbestos exposed worker: a specific programme developed in an Italian region — E. Chellini, F. Battisti, et al. (2018)

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