Early detection of central airway lung cancer in smokers with silicosis

Our plain-English summary of Early detection of central airway lung cancer in smokers with silicosis, by A.I. Lo, Y. Huang, S.Y. Lam, et al (The International Journal of Tuberculosis and Lung Disease, 2011).

The study

• Authors: A.I. Lo, Y. Huang, S.Y. Lam, A.H. Cheung, R. Au, C.C. Leung, W.K. Lam, M.S. Ip, M. Chan-Yeung, B. Lam
• Journal: The International Journal of Tuberculosis and Lung Disease
• Published: 2011;15(4):523-7
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Smokers with silicosis are at increased risk of lung cancer.

Objective: To evaluate the feasibility of using autofluorescence bronchoscopy after sputum examination for early detection of large airway lung cancer and factors associated with the presence of cancerous and pre-cancerous lesions among smokers with silicosis.

Methods: Subjects at the pneumoconiosis clinic were recruited if they fulfilled the following criteria: 1) age ≥40 years, 2) smoking history of ≥20 pack-years and 3) confirmed diagnosis of silicosis. Sputum specimens were collected for cytology/cytometry examination and autofluorescence bronchoscopy was performed in subjects with an abnormal sputum result.

Results: A total of 48 subjects were recruited during the study period. The mean age and smoking history were respectively 63 ± 10 years and 51 ± 30 pack-years. Intraepithelial lung cancers and pre-neoplastic lesions (squamous metaplasia or above) were detected in respectively 2 (4.2%) and 14 (29.2%) subjects. The proportions of current smokers (75.0% vs. 40.6%, P = 0.03) and asbestos exposure (37.5% vs. 9.4%, P = 0.04) were significantly higher in subjects with the above lesions compared with those without.

Conclusions: Sputum examination followed by autofluorescence bronchoscopy may be a useful way of identifying cancerous/pre-cancerous lesions among silicotic smokers. Current smoking and asbestos exposure were associated with these lesions.

In plain English

This small pilot study tested whether sputum (coughed-up mucus) tests followed by autofluorescence bronchoscopy, an airway examination, could find early large-airway cancer in smokers with silicosis. From June 2006 to March 2009, the researchers screened 720 people with silicosis and recruited 48 Chinese men with abnormal sputum results. Of these 48 men, 2 (4.2%) had early cancer within the airway lining (carcinoma in situ or severe dysplasia), 4 (8.4%) had mild to moderate dysplasia, and 10 (20.8%) had squamous metaplasia. Men with squamous metaplasia or worse were more often current smokers than men without such changes (75.0% vs. 40.6%, P = 0.03) and more often had asbestos exposure (37.5% vs. 9.4%, P = 0.04). The article did not describe the asbestos fiber type or source. During a median 23.8 months of follow-up, no lung cancers were diagnosed beyond the two found by screening. The authors concluded that this approach may be a useful way to identify cancerous or pre-cancerous lesions in silicotic smokers. They noted the small study size and that, without CT scans, outer-lung cancers may have been missed.

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: pilot screening study: sputum cytology/cytometry followed by autofluorescence bronchoscopy, with follow-up
• Who was studied: 720 people with silicosis screened from June 2006 to March 2009; 48 Chinese male smokers with silicosis and abnormal sputum results were recruited
• Exposure: Silicosis from occupational silica dust exposure, plus smoking. 9 of the 48 men (18.8%) had asbestos exposure. The article does not describe the fiber type or source of the asbestos exposure.
• Main results:
  • Endobronchial lesions were detected in 30 of the 48 subjects (62.5%)
  • Of the 48 subjects, 2 (4.2%) had intraepithelial neoplasm (CIS or severe dysplasia), 4 (8.4%) had mild to moderate dysplasia and 10 (20.8%) had squamous metaplasia
  • Compared with subjects with normal findings or hyperplasia or below, a higher proportion of subjects with metaplasia or above were current smokers (75.0% vs. 40.6%, P = 0.03) and had asbestos exposure (37.5% vs. 9.4%, P = 0.04)
  • The two groups showed no statistically significant differences in chest symptoms, comorbidities, spirometry, profusion score or progressive massive fibrosis size
  • Squamous metaplasia or worse was found in similar proportions of subjects with abnormal sputum cytology and subjects with abnormal cytometry (32.4% vs. 36.4%, P = 0.81)
  • Over a median follow-up of 23.8 months, no lung cancer cases were diagnosed other than the two detected by screening
  • In the two subjects with intraepithelial neoplasm who were treated with endobronchial cryotherapy, no tumour progression was observed during follow-up
• The authors' conclusion: The authors concluded that sputum examination followed by autofluorescence bronchoscopy may be a useful way of identifying cancerous or pre-cancerous lesions among silicotic smokers. In the discussion, they suggested it is essential for silicotic patients with abnormal sputum, particularly current smokers or those with asbestos exposure.
• Limitations the authors state:
  • Peripheral lung cancers, especially adenocarcinoma, may have been missed because chest CT was not used
  • There are no follow-up data for people who were screened but could not be recruited
  • This was a small pilot study, and its conclusions need to be verified in a larger cohort

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, Silicosis, Bronchoscopy, Sputum, Pneumoconiosis, Cytology, Asbestos Exposure.

Related studies

• Mortality of a cohort of men in a silicosis register: further evidence of an association with lung cancer — T.P. Ng, S.L. Chan, et al. (1990)
• Silicosis among foundry workers. Implication for the need to revise the OSHA standard — K.D. Rosenman, M.J. Reilly, et al. (1996)
• Radiographic evidence of silicosis risk in the diatomaceous earth industry — J.M. Hughes, H. Weill, et al. (1998)
• Enhanced retention of asbestos fibers in the airways of human smokers — A. Churg, B. Stevens (1995)
• Asbestosis and silicosis — G.R. Wagner (1997)
• Silicosis and smoking strongly increase lung cancer risk in silica-exposed workers — N. Kurihara, O. Wada (2004)

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