Soluble mesothelin-related protein in pleural effusion from patients with malignant pleural mesothelioma

Our plain-English summary of Soluble mesothelin-related protein in pleural effusion from patients with malignant pleural mesothelioma, by N. Fujimoto, K. Gemba, M. Asano, et al (Experimental and Therapeutic Medicine, 2010).

The study

• Authors: N. Fujimoto, K. Gemba, M. Asano, S. Wada, K. Ono, S. Ozaki, T. Kishimoto
• Journal: Experimental and Therapeutic Medicine
• Published: 2010;1(2):313-317
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Malignant pleural mesothelioma (MPM) is a highly aggressive neoplasm primarily arising from surface serosal cells of the pleura and is strongly associated with asbestos exposure. Patients with MPM often develop pleural fluid as initial presentation. However, cytological diagnosis using pleural fluid is usually difficult and has limited utility. A useful molecular marker for differential diagnosis particularly with lung cancer (LC) is urgently needed. The aim of the present study was to investigate the diagnostic value of soluble mesothelin-related protein (SMRP) in pleural fluid. Pleural fluids were collected from 23 patients with MPM, 38 with LC, 26 with benign asbestos pleurisy (BAP), 5 with tuberculosis pleurisy (TP) and 4 with chronic heart failure (CHF), and the SMRP concentration was determined. All data were analyzed by using non-parametric two-sided statistical tests. The median concentration of SMRP in MPM, LC, BAP, TP and CHF were 11.5 (range 0.90-82.80), 5.20 (0.05-36.40), 6.65 (1.45-11.25), 3.20 (1.65-6.50) and 2.03 (1.35-2.80) nmol/l, respectively. The SMRP concentration was significantly higher in MPM than in the other diseases (P=0.001). The area under the ROC curve (AUC) values of the MPM diagnosis was 0.75 for the differential diagnosis from the other groups. Based on the cut-off value of 8 nmol/l, the sensitivity and specificity for diagnosis of MPM were 70.0 and 68.4%, respectively. These results indicate that the SMRP concentration in pleural fluid is a useful marker for the diagnosis of MPM.

In plain English

This study, from Okayama Rosai Hospital in Japan, measured a protein called soluble mesothelin-related protein (SMRP) in the fluid that collects around the lungs (pleural fluid). The aim was to see whether it could help tell malignant pleural mesothelioma apart from other conditions. Between January 2004 and July 2007, fluid was collected from 23 patients with mesothelioma, 38 with lung cancer, 26 with benign asbestos pleurisy, 5 with tuberculosis pleurisy and 4 with chronic heart failure. The median SMRP level was 11.5 nmol/l in the mesothelioma group, and it was significantly higher than in the other diseases (P=0.001). Using a cut-off of 8 nmol/l, the test identified 70.0% of mesothelioma patients (sensitivity) and correctly excluded 68.4% of patients without mesothelioma (specificity). Among mesothelioma patients, SMRP showed no correlation with how long they had been exposed to asbestos at work. It also showed no correlation with asbestos bodies counted in lung tissue (17 patients) or with survival (22 patients). The authors concluded that pleural SMRP is useful as a diagnostic marker of mesothelioma. They cautioned that some results rest on a small number of cases.

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: Diagnostic marker study comparing SMRP levels in pleural fluid between patients with malignant pleural mesothelioma and patients with other diseases that cause pleural effusion
• Who was studied: Patients at Okayama Rosai Hospital, Japan, January 2004 to July 2007: 23 with malignant pleural mesothelioma (MPM; median age 64, 21 men and 2 women), 38 with lung cancer (pleural metastasis), 26 with benign asbestos pleurisy, 5 with tuberculosis pleurisy and 4 with chronic heart failure
• Exposure: Occupational asbestos exposure, with no fiber types specified. 21 of the 23 MPM patients had occupational exposure, and its duration was obtained by patient interview. Table I gives a median exposure period of 33 years (range 5-51) for MPM and 30 years (range 3-46) for benign asbestos pleurisy. Asbestos bodies in lung tissue were counted in 17 MPM cases.
• Main results:
  • Median pleural fluid SMRP was 11.5 nmol/l (range 0.9-82.8) in MPM, 5.2 (0.05-36.4) in lung cancer, 6.65 (1.45-11.25) in benign asbestos pleurisy, 3.20 (1.65-6.5) in tuberculosis pleurisy and 2.03 (1.35-2.8) in chronic heart failure. SMRP was significantly higher in MPM than in the other diseases (P=0.001).
  • For telling MPM apart from all other groups, the AUC was 0.75 (95% CI 0.615-0.884). At a cut-off of 8 nmol/l, sensitivity was 70.0% and specificity 68.4%.
  • MPM compared with lung cancer: SMRP was significantly higher in MPM (P=0.004). The AUC was 0.724 (95% CI 0.583-0.866). At 8 nmol/l, sensitivity was 69.6% and specificity 68.4%.
  • MPM compared with benign asbestos pleurisy: SMRP was significantly higher in MPM (P=0.004). The AUC was 0.74 (95% CI 0.586-0.894). At 8 nmol/l, sensitivity was 69.6% and specificity 69.2%.
  • Within MPM, SMRP tended to be higher in advanced stages (III and IV) than in early stages (I and II), and higher in the epithelioid subtype than in the sarcomatoid subtype. Neither difference was statistically significant (P=0.158 and 0.389, respectively).
  • In MPM patients, SMRP showed no correlation with duration of asbestos exposure (Pearson coefficient -0.069). It also showed no correlation with the number of asbestos bodies in 17 cases (median 2,180, range 239-526,000 per gram of lung; coefficient -0.156).
  • In the 22 MPM patients with survival data, SMRP showed no correlation with survival (coefficient -0.179). Survival did not differ statistically between patients with SMRP at or below 8.0 nmol/l and those above it.
• The authors' conclusion: The authors concluded that pleural fluid SMRP was significantly higher in MPM than in the other diseases and is useful as a diagnostic marker of MPM. They also interpreted the lack of correlation with asbestos measures to mean that SMRP elevation in MPM is not influenced by asbestos but is a cancer-specific event.
• Limitations the authors state:
  • The authors attributed the non-significant differences by subtype and stage probably to the small number of samples.
  • The authors said the survival (prognosis) findings should be interpreted carefully because of the small number of cases.

Topics

Medical terms in this study, explained in our Lexicon: Mesothelin, Pleural Effusion, Pleural Mesothelioma, Neoplasm, Pleura, Asbestos Exposure, Differential Diagnosis, Lung Cancer.

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• 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)
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