Lung cancer screening in patients with Libby amphibole disease: High yield despite predominantly environmental and household exposure

Our plain-English summary of Lung cancer screening in patients with Libby amphibole disease: High yield despite predominantly environmental and household exposure, by G. Loewen, B. Black, T. McNew, et al (American Journal of Industrial Medicine, 2019).

The study

• Authors: G. Loewen, B. Black, T. McNew, A. Miller
• Journal: American Journal of Industrial Medicine
• Published: 2019;62(12):1112-1116
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Lung cancer screening with low-dose computed tomography (CT) scanning (LDCT) is accepted as a screening tool, but its application to populations exposed to recognized occupational or environmental carcinogens is limited. We apply LDCT to a population with a predominantly nonoccupational exposure to a recognized human lung carcinogen, Libby amphibole asbestos (LA).

Methods: Patients in an asbestos disease clinic in Libby, Montana who were aged 50 to 84 years, greater than or equal to 20 pack-year history of tobacco use (irrespective of quit date), and asbestos-related pleuropulmonary disease on high-resolution CT scan were offered free annual lung cancer screening over a 39-month period.

Results: Of 2897 clinic patients, 1149 (39.7%) met eligibility criteria, and 567 (49%) were screened with 1014 low-dose CT scans. Most screened patients had principally environmental (333 or 59%) or household exposure (145 or 25%) to LA. Seventeen primary lung cancers were identified, mostly in early stages: 10 at stage 1, two at stage 2, three at stages 3 to 4, and two at limited small-cell cancers. The screening yield was 1.9 at baseline scan and 1.5% on the first annual scan.

Conclusions: Consistent with the guidelines of the National Comprehensive Cancer Network and American Association of Thoracic Surgery, LDCT for early lung cancer detection should be offered to people with significant exposure to occupational or environmental human lung carcinogens.

© 2019 The Authors. American Journal of Industrial Medicine Published by Wiley Periodicals, Inc.

In plain English

This report described a free annual low-dose CT lung cancer screening program at an asbestos disease clinic in Libby, Montana, for patients exposed to Libby amphibole asbestos. Eligible patients were aged 50 to 84, had smoked more than 20 pack-years, and had asbestos-related disease on an earlier chest CT. Of 1149 eligible patients, 567 were screened between February 2013 and May 2016. For 478 of them (84%), exposure was non-occupational: they lived with a mine or lumber worker, or were exposed through the environment. Seventeen lung cancers were found. The screening yield was 1.9% (11 of 567) at the first scan and 1.5% (5 of 325) at the first annual scan. Ten cancers were stage 1, two were stage 2, three were stage 3 to 4, and two were limited small-cell cancers. Of the 17 people with lung cancer, 7 would have qualified under US Preventive Services Task Force screening criteria. The authors concluded that environmental or occupational exposure to lung carcinogens can usefully be included in screening eligibility criteria. They noted limits including a small cohort and a 49% participation rate.

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: Descriptive report of a clinic-based low-dose CT (LDCT) lung cancer screening program, with no unscreened comparison group
• Who was studied: Patients of the Center for Asbestos-Related Disease (CARD) in Libby, Montana. Eligibility: aged 50 to 84, more than 20 pack-years of cigarette smoking, free of lung cancer symptoms, and asbestos-related disease on a prior high-resolution chest CT. 1149 patients were eligible and 567 took part between February 2013 and May 2016.
• Exposure: Libby amphibole (LA) asbestos from vermiculite mined near Libby. Among the 567 screened, exposure was predominantly environmental for 333 (59%), household (living with a mine or lumber mill worker) for 145 (25%) and occupational (mine and lumber mill workers) for 89 (16%). In total, 478 (84%) had non-occupational exposure.
• Main results:
  • Seventeen lung cancers were identified among the 567 people screened.
  • Screening yield (cancers among people screened) by round: 1.9% (11 of 567) at baseline, 1.5% (5 of 325) at the first annual scan, 0.99% (1 of 102) at the second annual scan, and 0 (0 of 10) at the third annual scan.
  • Stage at diagnosis of the 17 lung cancers: 10 at stage 1, 2 at stage 2, 3 at stages 3 to 4, and 2 were limited small-cell cancers.
  • Fifteen cancers were confirmed by CT-guided needle biopsy. Two presumed stage 1A non-small-cell cancers were not biopsied and were treated with stereotactic body radiotherapy.
  • Cell types of the 15 biopsied cancers: 9 adenocarcinoma, 2 squamous cell, 1 combined squamous cell and adenocarcinoma, 2 small-cell carcinoma, and 1 large-cell neuroendocrine.
  • Radiographic asbestos-related fibrosis pattern in the 17 lung cancer cases: diffuse (lamellar) pleural thickening, with or without plaques, in 14; discrete pleural plaques alone in 1; interstitial fibrosis alone in 2.
  • Under the USPSTF screening eligibility criteria, 41% (7 of 17) of the patients with lung cancer would have been eligible. Under National Lung Screening Trial criteria, 35% (6 of 17) would have been eligible.
  • Compared with eligible patients who did not enroll, participants had a shorter duration of LA exposure and were more likely to have had environmental exposure.
  • Besides the lung cancers, one participant was diagnosed with thymic carcinoma and another with diffuse large B-cell lymphoma (stage IVB).
• The authors' conclusion: The authors concluded that their results add to growing evidence that environmental or occupational exposure to lung carcinogens can usefully be included in eligibility criteria for lung cancer screening. They considered their yields comparable to those of occupational screening studies.
• Limitations the authors state:
  • Relatively small cohort
  • Incomplete compliance with annual scans
  • Only 49% of eligible patients took part
  • Two lung cancers were not confirmed by tissue
  • Participants were enrollees in a disease surveillance program, not a population-based sample, which limits generalizability
  • Participants had a prior CT on average about 2.5 years earlier, so slow-growing cancers may already have been found, lowering the program's yield

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: Low-Dose CT Screening, Libby amphiboles, High-Resolution CT (HRCT), CT Scan, Lung Cancer, Thoracic Surgery.

Related studies

• Social Support Functions During a Slowly-Evolving Environmental Disaster: The Case of Amphibole Asbestos Exposure in Libby, Montana — R.J. Cline, H. Orom, et al. (2015)
• Determining satisfaction with access and financial aspects of care for persons exposed to Libby amphibole asbestos: rural and national environmental policy implications — C.A. Winters, W. Hill, et al. (2011)
• Pulmonary abnormalities as a result of exposure to Libby amphibole during childhood and adolescence-The Pre-Adult Latency Study (PALS) — J. Szeinuk, C.W. Noonan, et al. (2017)
• Rapid progression of pleural disease due to exposure to Libby amphibole: "Not your grandfather's asbestos related disease" — B. Black, J. Szeinuk, et al. (2014)
• Libby Amphibole Disease: Pulmonary Function and CT Abnormalities in Vermiculite Miners — A. Miller, J. Szeinuk, et al. (2018)
• "Not your grandfather's pleural disease": rapid progression, ventilatory impairment, and chronic pleuritic pain from Libby vermiculite/amphibole — A. Miller (2014)

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