Follow-up of Soluble Mesothelin-Related Protein Levels in Participants With Asbestos-Related Disorders

Our plain-English summary of Follow-up of Soluble Mesothelin-Related Protein Levels in Participants With Asbestos-Related Disorders, by E.K. Park, A.R. Johnson, D. Wilson, et al (Safety and Health at Work, 2020).

The study

• Authors: E.K. Park, A.R. Johnson, D. Wilson, P.S. Thomas, D.H. Yates
• Journal: Safety and Health at Work
• Published: 2020;11(4):425-430
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Asbestos exposure is associated with the development of the cancer malignant mesothelioma (MM). Measurement of soluble mesothelin-related protein (SMRP) has been suggested as a method for detection of MM in its early stages. We prospectively examined SMRP levels in participants with asbestos exposure who are a group at a high risk of development of MM.

Methods: This study was a follow-up of our cohort of 322 asbestos-exposed participants. No further participants developed MM or malignancy over the study period. Mean follow-up time was 22.9 months.

Results: Mean (standard deviation) SMRP levels at baseline and follow-up were 0.94 (0.79) and 0.91 (0.86) nmol/L (p = 0.1033), respectively. Mean SMRP levels of the healthy individuals exposed to asbestos at baseline was significantly lower than those of participants with asbestosis and pleural plaques alone; similar patterns were found on follow-up measurements. There was a statistically significant effect of age on serial SMRP measurements. Our study confirms higher levels in participants with nonmalignant asbestos-related disorders. Levels decreased in asbestos-related disorders other than asbestosis, where a small increase was observed. We did not detect any further cases of malignancy.

Conclusion: Monitoring programs for early detection of MM need to take into account increased SMRP levels found in benign asbestos-related diseases.

© 2020 Occupational Safety and Health Research Institute, Published by Elsevier Korea LLC.

In plain English

This study followed up asbestos-exposed people seen at the Workers' Compensation (Dust Diseases) Board of New South Wales in Sydney, Australia. The authors measured a blood protein, soluble mesothelin-related protein (SMRP), which has been suggested as a possible early sign of malignant mesothelioma. Of 322 participants followed between February 2007 and November 2008, 297 were analysed, and 99% were men. Average SMRP was 0.94 nmol/L at baseline and 0.91 nmol/L at follow-up, a mean of 22.9 months later. This difference was not statistically significant. Exposed people with no apparent asbestos-related disease had significantly lower levels than those with asbestosis or with pleural plaques alone. Levels fell significantly in the 49 people with diffuse pleural thickening. Age, but not body mass index, had a statistically significant effect on levels over time. No participant developed mesothelioma or any other cancer during the study. The authors concluded that monitoring programs need to take account of higher SMRP levels in benign asbestos-related diseases. They noted that the absence of new mesothelioma cases limited the study's relevance to screening.

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: Prospective follow-up of an existing cohort of asbestos-exposed participants (observational study), with blood SMRP measured at baseline and at follow-up
• Who was studied: 322 asbestos-exposed participants from a cohort at the Workers' Compensation (Dust Diseases) Board of New South Wales, Sydney, Australia, followed up between February 2007 and November 2008 (mean follow-up 22.9 months, range 12 to 32). 99% were men (2 women). After excluding 9 people with silicosis and 16 whose diagnosis changed, 297 were analysed: 145 healthy but asbestos-exposed, 90 with pleural plaques alone, 49 with diffuse pleural thickening, 7 with asbestosis, and 6 with asbestosis and diffuse pleural thickening.
• Exposure: Past asbestos exposure. The article does not specify fiber types, jobs or doses. The outcome measured was serum SMRP (nmol/L).
• Main results:
  • Whole group: mean SMRP was 0.94 (SD 0.79) nmol/L at baseline and 0.91 (SD 0.86) nmol/L at follow-up (p = 0.1033, not statistically significant).
  • Healthy asbestos-exposed group (n = 145): 0.75 (0.42) nmol/L at baseline and 0.78 (0.46) nmol/L at follow-up (p = 0.1847).
  • Pleural plaques alone (n = 90): 1.20 (1.09) nmol/L at baseline and 1.12 (1.26) nmol/L at follow-up (p = 0.1182).
  • Asbestosis (n = 7): 1.66 (1.37) nmol/L at baseline and 1.75 (1.31) nmol/L at follow-up (p = 0.7881).
  • Diffuse pleural thickening (n = 49): levels fell significantly, from 0.93 (0.65) nmol/L at baseline to 0.72 (0.66) nmol/L at follow-up (p = 0.0003).
  • Asbestosis with diffuse pleural thickening (n = 6): 1.32 (0.93) nmol/L at baseline and 1.16 (0.51) nmol/L at follow-up (p = 0.4085).
  • At baseline, the healthy asbestos-exposed group had significantly lower SMRP than the asbestosis group and the pleural plaques group (p less than 0.05 for each). A similar pattern was seen at follow-up, when the asbestosis group was also significantly higher than the diffuse pleural thickening group.
  • Individual SMRP levels at the two sampling points were correlated (Spearman r = 0.6064, 95% CI 0.5267 to 0.6756, p less than 0.0001).
  • In mixed models adjusted for smoking, age had a statistically significant effect on serial SMRP measurements (coefficient 0.083, p less than 0.001).
  • Body mass index did not significantly affect change in SMRP over time.
  • No participant developed mesothelioma or any other malignancy during the study period.
• The authors' conclusion: The authors concluded that monitoring programs for early detection of malignant mesothelioma need to take into account the increased SMRP levels found in benign asbestos-related diseases.
• Limitations the authors state:
  • Because the study was observational and voluntary, blood sampling and computed tomography were not mandatory.
  • Follow-up time and the time between blood samples were not the same for all participants.
  • No new cases of mesothelioma occurred, which reduced the study's relevance to mesothelioma screening.
  • The authors said that a change seen in the pleural plaques group may reflect regression to the mean or potential selection bias.

Topics

Medical terms in this study, explained in our Lexicon: Mesothelin, Asbestos Exposure, Mesothelioma, Soluble Mesothelin-Related Peptides (SMRP), Pleural Plaques.

Related studies

• Factors affecting soluble mesothelin related protein levels in an asbestos-exposed population — E.K. Park, P.S. Thomas, et al. (2010)
• A predictive equation to adjust for clinical variables in soluble mesothelin-related protein (SMRP) levels — E.K. Park, D. Wilson, et al. (2012)
• Soluble mesothelin-related protein in an asbestos-exposed population: the dust diseases board cohort study — E.K. Park, A. Sandrini, et al. (2008)
• Soluble mesothelin related peptides (SMRP) and osteopontin as protein biomarkers for malignant mesothelioma: analytical validation of ELISA based assays and characterization at mRNA and protein levels — A.J. Rai, R.M. Flores, et al. (2010)
• Serum soluble mesothelin-related protein (SMRP) and fibulin-3 levels correlate with baseline malignant pleural mesothelioma (MPM) tumor volumes but are not useful as biomarkers of response in an immunotherapy trial — S.I. Katz, L. Roshkovan, et al. (2021)
• Mesothelin (MSLN) methylation and soluble mesothelin-related protein levels in a Chinese asbestos-exposed population — M. Yu, Y. Zhang, et al. (2015)

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