Assessment of biomarkers in asbestos-exposed workers as indicators of cancer risk

Our plain-English summary of Assessment of biomarkers in asbestos-exposed workers as indicators of cancer risk, by M. Amati, M. Tomasetti, L. Mariotti, et al (Mutation Research, 2008).

The study

• Authors: M. Amati, M. Tomasetti, L. Mariotti, L.M. Tarquini, M. Valentino, L. Santarelli
• Journal: Mutation Research
• Published: 2008;655(1-2):52-8
• Cited by: 26 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Epidemiological studies have shown that mortality from malignant mesothelioma (MM) and lung cancer have increased with increasing cumulative exposure to asbestos. To investigate whether tumour-related biomarkers can contribute towards the evaluation of the carcinogenic risk in populations exposed to asbestos, the DNA adduct 8-hydroxy-2'-deoxyguanosine (80HdG), interleukine-6 (IL-6), platelet-derived growth factor (PDGF-BB), hepatocyte growth factor (HGF), basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGFbeta) and soluble mesothelin-related peptides (SMRPs) were analysed in a cohort of workers differently exposed to asbestos fibres at the workplace. To document biomarker levels in an unexposed population, 54 age-matched subjects were enrolled. A total of 119 subjects with a history of occupational exposure to asbestos underwent clinical examination and were interviewed by trained personnel, responding to a detailed questionnaire related to duration of asbestos exposure, smoking, and occupational task. According to the occupational tasks, asbestos-exposed subjects were analysed for their asbestos cumulative dose and the association with the biomarkers was evaluated. Among the occupational groups, maintenance workers, pipe fitters and electricians were exposed to a higher cumulative dose of asbestos fibres. Exposure to asbestos significantly increased the steady-state content of 80HdG in DNA. Elevated levels of 80HdG and IL-6 best reflected a high level of SMRPs, which is related to cell transformation. Subjects heavily exposed to asbestos [> 60(ff/cm3) x years] showed also a higher level of angiogenic factors. A combination of angiogenic biomarkers with a specific mesothelioma-biomarker such as SMRPs could be used for close surveillance of workers with a history of asbestos exposure.

In plain English

An Italian study measured blood markers in 119 occupationally asbestos-exposed people and 54 age-matched unexposed people. Exposed people were enrolled in 2004 to 2005 after invitations to shipbuilding-industry workers. Markers included 8OHdG (a sign of oxidative DNA damage), inflammation marker IL-6, four growth factors including VEGF, and SMRPs, a mesothelioma-related marker. Cumulative dose was estimated in fibre-years from job tasks, using an arbitrary coefficient. 8OHdG averaged 8.2 arbitrary units in exposed subjects and 5.1 in controls. Maintenance workers, pipe fitters and electricians had the highest estimated doses. Pleural plaques or fibrosis were found in 71%, 57% and 50% of them, versus 10% of office employees. SMRPs were associated with 8OHdG and IL-6, and 8OHdG and VEGF were associated with cumulative dose. Subjects above 60 fibre-years had higher SMRPs and IL-6. No relationship was observed between biomarkers and smoking or exposure duration (data not shown). The authors concluded that combining growth-factor markers with SMRPs could be used for close surveillance of workers with long exposure, pleural plaques and lung fibrosis; the study did not test this. They noted the growth factors lack specificity.

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 biomarker study of asbestos-exposed workers, compared with an unexposed age-matched control group
• Who was studied: 119 subjects with a history of occupational asbestos exposure (95 males, 24 females; mean age 63), enrolled November 2004 to September 2005 at the Clinic of Occupational Medicine, Polytechnic University of Marche, Ancona, Italy. Of these, 95 had worked in shipbuilding and 24 were office employees with lower exposure. A further 54 age-matched unexposed controls (33 males, 21 females) were recruited from November 2004 to January 2007.
• Exposure: Occupational asbestos exposure, mainly in the shipbuilding industry. Cumulative dose was estimated in fibre-years by assigning each person an arbitrary coefficient of inhaled fibres based on job hazard. Fibre type was not measured. The authors applied a relative-risk formula with a coefficient for chrysotile, stating that chrysotile is the most common type used in shipbuilding.
• Main results:
  • The oxidative DNA damage marker 8OHdG in white blood cells was higher in the asbestos-exposed group (8.2 ± 3.8 arbitrary units) than in the control group (5.1 ± 2.1).
  • Within the exposed group, males had higher 8OHdG and SMRPs than females. The authors attributed this to all females being office workers with low exposure.
  • Asbestos-related diseases (fibrosis and pleural plaques) were found in 37 (31%) of the 119 exposed subjects.
  • Maintenance workers, pipe fitters and electricians had the highest estimated cumulative doses (mean 125, 114 and 108 fibre-years in Table 3). Pleural plaques and fibrosis were found in 71%, 57% and 50% of them, compared with 10% of office employees.
  • In multiple regression among exposed workers, SMRPs were associated with IL-6 and 8OHdG. 8OHdG was associated with cumulative fibre dose, and cumulative dose was associated with VEGF.
  • The growth factors HGF, bFGF and VEGF and the marker SMRPs were significantly higher in highly exposed job groups such as maintenance workers and pipe fitters.
  • By cumulative-dose group, SMRPs and IL-6 were higher in subjects above 60 fibre-years. Angiogenic factors were elevated in subjects above 10 and above 60 fibre-years (p less than 0.05).
  • No relationship was observed between biomarker concentrations and smoking or the duration of asbestos exposure (data not shown). The presence of pleural plaques and lung fibrosis did not affect the biomarkers (data not shown).
• The authors' conclusion: The authors concluded that combining angiogenic biomarkers with a mesothelioma-specific biomarker such as SMRPs could be used for close surveillance of workers with a long history of asbestos exposure, pleural plaques and lung fibrosis.
• Limitations the authors state:
  • The authors state that the angiogenic factors, although sensitive in discriminating subjects at high risk, lack specificity.

Topics

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

Medical terms in this study, explained in our Lexicon: Biomarker, Malignant Mesothelioma, Lung Cancer, Cumulative Exposure, Carcinogenic, Platelet-Derived Growth Factor (PDGF), Fibroblast, Soluble Mesothelin-Related Peptides (SMRP).

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