Occupational and nonoccupational factors associated with high grade bronchial pre-invasive lesions

Our plain-English summary of Occupational and nonoccupational factors associated with high grade bronchial pre-invasive lesions, by C. Paris, J. Benichou, S. Bota, et al (The European Respiratory Journal, 2003).

The study

• Authors: C. Paris, J. Benichou, S. Bota, S. Sagnier, J. Metayer, S. Eloy, J.B. Auliac, G. Nouvet, L. Thiberville
• Journal: The European Respiratory Journal
• Published: 2003;21(2):332-41
• Cited by: 16 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Besides tobacco exposure, factors associated with the development of pre-invasive bronchial lesions are not known. Autofluorescence bronchoscopy was used to assess the prevalence of severe dysplasia and carcinoma in situ (SD/CIS) of the proximal bronchial tree in relation to occupational or nonoccupational carcinogen exposure. Among the 241 individuals in this study, the overall prevalence of at least one SD/CIS was 9% (21 subjects). Multivariable analysis revealed significant and independent associations between presence of SD/CIS and: 1) active smoking, relative to former smokers; 2) presence of synchronous invasive lung cancer; 3) duration of asbestos exposure and; 4) exposure to other occupational carcinogens. The independent associations of synchronous lung cancer with severe dysplasia and carcinoma, after adjusting for both occupational and nonoccupational carcinogen exposures, suggest other mechanisms than a field cancerisation may be involved in the carcinogenesis of these pre-invasive lesions. Moreover, active smokers, patients with recently resected invasive lung cancer and workers occupationally exposed to bronchial carcinogens may represent a population of choice for early cancer endoscopic detection programmes in view of their high severe dysplasia and carcinoma prevalence.

In plain English

This cross-sectional study used baseline data from an early lung cancer detection programme in Rouen, France. Participants had treated lung, laryngeal or oesophageal cancer, at least 30 pack-years of smoking, or significant work exposure to respiratory carcinogens. Between February 1995 and June 2000, 241 people had fluorescence bronchoscopy and a risk-factor interview. 146 had occupational asbestos exposure. Overall, 21 people (9%) had high grade pre-invasive lesions (severe dysplasia or carcinoma in situ) in the proximal airways. None of the 13 nonsmokers had such lesions; they were left out of the association analyses. Among the other 228, after adjustment, these lesions were associated with current smoking, invasive lung cancer present or treated within the past year, duration of asbestos exposure (odds ratio 10.8, 95% CI 2.2 to 53.7, for 20 years or more versus none) and exposure to other workplace carcinogens for 10 years or more. The authors concluded that occupational carcinogens, particularly asbestos fibres, were independently associated with these lesions. They noted the few cases and that cross-sectional data cannot prove the exposures are risk factors.

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: Cross-sectional analysis of baseline examinations in an early lung cancer detection programme (white-light and fluorescence bronchoscopy plus a standardised risk-factor questionnaire)
• Who was studied: 241 subjects at high risk of lung cancer (including 13 nonsmokers) recruited February 1995 to June 2000 at Rouen University Hospital, France. Eligibility required treated lung, laryngeal or oesophageal cancer, at least 30 pack-years of smoking, or significant occupational exposure to respiratory carcinogens. Mean age was 57.7 years and 90% were male. Association analyses used the 228 current or former smokers.
• Exposure: Occupational asbestos exposure (fiber type not specified), assessed by an expert from job histories for probability and duration, using factory data or the French job exposure matrix EVALUTIL. Also assessed: definite exposure for more than 10 years to other respiratory carcinogens such as silica, polycyclic aromatic hydrocarbons, and nickel and chrome salts, and smoking. 146 subjects (61%) were asbestos-exposed and 31 (13%) were exposed to other occupational carcinogens.
• Main results:
  • 21 of 241 subjects (9%) had high grade pre-invasive lesions: nine with severe dysplasia and 12 with carcinoma in situ.
  • No high grade lesions were found among the 13 nonsmokers, who were therefore excluded from the univariable and multivariable association analyses.
  • In univariable analysis, subjects ever exposed to asbestos had an odds ratio of 4.5 (95% CI 1.3 to 15.8) for high grade lesions compared with unexposed subjects (18 of 136 exposed versus 3 of 92 unexposed). The authors describe this as a prevalence of 13% versus 3%.
  • In the multivariable model, compared with no asbestos exposure, the odds ratio for high grade lesions was 6.7 (95% CI 1.2 to 36.6) for less than 20 years of asbestos exposure and 10.8 (95% CI 2.2 to 53.7) for 20 years or more (p=0.014).
  • With asbestos exposure duration treated as a continuous variable and adjusted for the same factors, the odds ratio was 1.062 per year of exposure (95% CI 1.022 to 1.104).
  • In the multivariable model, synchronous invasive lung cancer (odds ratio 11.7, 95% CI 3.1 to 43.4) and current smoking compared with former smoking (odds ratio 6.7, 95% CI 1.5 to 29.4) were independently associated with high grade lesions.
  • In the multivariable model, exposure to other occupational carcinogens for 10 years or more had an odds ratio of 5.9 (95% CI 1.7 to 20.7) for high grade lesions.
  • A history of cured ear, nose and throat cancer was no longer statistically significant in the multivariable analysis (odds ratio 4.5, 95% CI 0.7 to 30.5).
• The authors' conclusion: The authors concluded that occupational exposure to respiratory carcinogens, particularly asbestos fibres, was independently associated with high grade pre-invasive lesions of the proximal bronchus. They also concluded that active smoking was independently associated with these lesions. They suggested that active smokers exposed to occupational carcinogens and patients with recently resected lung cancer may be suitable for endoscopic early-detection programmes.
• Limitations the authors state:
  • The number of subjects with high grade lesions was small (21), so the authors said results should be confirmed in larger studies.
  • Subjects were a narrowly selected high-risk group, so results may apply only to high-risk subjects.
  • Very few nonsmokers were included, limiting assessment of tobacco-related risk.
  • Findings apply only to lesions preceding squamous cell carcinoma in the accessible proximal bronchial tree.
  • Fluorescence endoscopy may not detect all pre-invasive lesions.
  • The data are cross-sectional and do not prove that the associated exposures are risk factors.

Topics

Medical terms in this study, explained in our Lexicon: Bronchoscopy, Carcinoma, Lung Cancer, Asbestos Exposure, Carcinogenesis.

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