Calretinin as a blood-based biomarker for mesothelioma

Our plain-English summary of Calretinin as a blood-based biomarker for mesothelioma, by G. Johnen, K. Gawrych, I. Raiko, et al (BMC Cancer, 2017).

The study

• Authors: G. Johnen, K. Gawrych, I. Raiko, S. Casjens, B. Pesch, D.G. Weber, D. Taeger, M. Lehnert, J. Kollmeier, T. Bauer, A.W. Musk, B.W.S. Robinson, T. Brüning, J. Creaney
• Journal: BMC Cancer
• Published: 2017;17(1):386
• Cited by: 35 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Malignant mesothelioma (MM) is a deadly cancer mainly caused by previous exposure to asbestos. With a latency period up to 50 years the incidence of MM is still increasing, even in countries that banned asbestos. Secondary prevention has been established to provide persons at risk regular health examinations. An earlier detection with tumor markers might improve therapeutic options. Previously, we have developed a new blood-based assay for the protein marker calretinin. Aim of this study was the verification of the assay in an independent study population and comparison with the established marker mesothelin.

Methods: For a case-control study in men, a total of 163 cases of pleural MM and 163 controls were available from Australia, another 36 cases and 72 controls were recruited in Germany. All controls had asbestosis and/or plaques. Calretinin and mesothelin were determined by ELISA (enzyme-linked immunosorbent assay) in serum or plasma collected prior to therapy. We estimated the performance of both markers and tested factors potentially influencing marker concentrations like age, sample storage time, and MM subtype.

Results: Calretinin was able to detect all major subtypes except for sarcomatoid MM. Calretinin showed a similar performance in Australian and German men. At a pre-defined specificity of 95% the sensitivity of calretinin reached 71% and that of mesothelin 69%, when excluding sarcomatoid MM. At 97% specificity, the combination with calretinin increased the sensitivity of mesothelin from 66% to 75%. Sample storage time did not influence the results. In controls the concentrations of calretinin increased 1.87-fold (95% CI 1.10-3.20) per 10 years of age and slightly more for mesothelin (2.28, 95% CI 1.30-4.00).

Conclusions: Calretinin could be verified as a blood-based marker for MM. The assay is robust and shows a performance that is comparable to that of mesothelin. Retrospective analyses would not be limited by storage time. The high specificity supports a combination of calretinin with other markers. Calretinin is specific for epithelioid and biphasic MM but not the rarer sarcomatoid form. Molecular markers like calretinin and mesothelin are promising tools to improve and supplement the diagnosis of MM and warrant further validation in a prospective study.

In plain English

This case-control study assessed the blood protein calretinin as a marker of malignant mesothelioma (MM), compared with the established marker mesothelin. All participants were men: 163 MM cases and 163 controls from Australia, and 36 and 72 from Germany. All controls had asbestosis and/or pleural plaques. In one Australian group, calretinin was significantly higher than in controls for epithelioid and biphasic MM but not sarcomatoid MM, while mesothelin was significantly higher for all types. After sarcomatoid cases were excluded, at a cutoff giving 5% false positives among controls, calretinin detected 71% of cases and mesothelin 69%. At a 3% false-positive rate, combining the two raised detection from 66% (mesothelin alone) to 75%. Storage time showed no overall influence on calretinin, though in controls there was a weak, statistically significant correlation. In controls, each ten years of age went with 1.87-fold more false-positive calretinin tests (95% CI 1.10 to 3.20) and 2.28-fold more for mesothelin (95% CI 1.30 to 4.00). The authors concluded that calretinin performed comparably to mesothelin. They noted that their design tends to overestimate sensitivity and called for a prospective study.

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: Case-control study of blood biomarkers (calretinin and mesothelin, measured by ELISA)
• Who was studied: Men only. From Australia: 163 MM cases and 163 controls. From Germany: 36 cases and 72 controls. All controls had asbestosis and/or plaques. The samples formed three groups. Group 1 (Australia) had 83 cases with epithelioid, biphasic and sarcomatoid tumors and 88 controls with plaques; some samples were up to 15 years old. Group 2 (Australia) had 80 cases and 75 controls, and group 3 (Germany) had 36 cases and 72 controls. Blood was drawn between 1996 and 2014.
• Exposure: The study measured calretinin and mesothelin levels in blood. Asbestos exposure was not measured. Controls had benign asbestos-related disease (pleural plaques and/or asbestosis). The German controls came from a surveillance cohort of workers with previous asbestos exposure and a recognized occupational disease. No fiber types or doses are given.
• Main results:
  • Group 1 (Australia), all subtypes combined: median calretinin was 0.79 ng/mL in MM cases versus less than 0.19 ng/mL in controls (p = 0.0197).
  • Group 1, by subtype: median calretinin was 1.00 ng/mL for epithelioid, 0.29 ng/mL for sarcomatoid and 1.53 ng/mL for biphasic MM. Sarcomatoid cases did not differ significantly from controls (p = 0.2200).
  • Group 1, mesothelin: levels in MM cases differed significantly from controls for every subtype, including sarcomatoid (p < 0.0001).
  • Groups 2 and 3, sarcomatoid cases excluded: median calretinin was 1.10 ng/mL in Australian cases versus less than 0.01 ng/mL in Australian controls, and 1.01 ng/mL in German cases versus 0.20 ng/mL in German controls. Calretinin levels did not differ significantly between the two countries, either for cases (p = 0.8210) or for controls (p = 0.0773).
  • Groups 2 and 3 pooled (116 cases, 147 controls): with the false-positive rate set at 5% (95% specificity), calretinin detected 71% of cases (82 of 116) and mesothelin 69% (80 of 116). At a 1% false-positive rate, calretinin detected 52% and mesothelin 61%.
  • Groups 2 and 3 pooled, area under the ROC curve (a measure of overall accuracy): nonparametric value 0.86 (95% CI, 0.82 to 0.91) for calretinin and 0.89 (95% CI, 0.85 to 0.93) for mesothelin.
  • Groups 2 and 3 pooled, combined test: with specificity set at 97% and either marker being positive enough for a positive result, sensitivity was 75%, compared with 66% for mesothelin alone.
  • All three groups, storage time: the authors observed no influence of storage time on calretinin concentrations. There was no significant correlation in cases and a weak correlation in controls. The odds ratio of a false-positive calretinin test in controls was 1.02 (95% CI, 1.01 to 1.03).
  • Groups 2 and 3 pooled, age: calretinin showed no significant correlation with age. In controls, ten more years of age was associated with 1.87-fold more false-positive calretinin tests (95% CI, 1.10 to 3.20) and 2.28-fold more false-positive mesothelin tests (95% CI, 1.30 to 4.00).
• The authors' conclusion: The authors concluded that calretinin was verified as a blood-based marker for MM. They described the assay as robust, with performance comparable to mesothelin. They stated that it detects epithelioid and biphasic MM but not the sarcomatoid form, and that it warrants validation in a prospective study.
• Limitations the authors state:
  • The authors state that the case-control design tends to overestimate sensitivity compared with a prospective design.
  • Because the disease is rare, the authors had to use archived samples.
  • Samples came mainly from already diagnosed, often later-stage cases. The authors expect marker levels to be lower in people who do not yet have symptoms.
  • The authors state that a nested case-control study would have been the preferred design.

Topics

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

Medical terms in this study, explained in our Lexicon: Calretinin, Biomarker, Mesothelioma, Malignant Mesothelioma, Latency, Tumor Marker, Mesothelin, Case-Control Study.

Related studies

• Mesothelin, Calretinin, and Megakaryocyte Potentiating Factor as Biomarkers of Malignant Pleural Mesothelioma — C. Jiménez-Ramírez, S. Casjens, et al. (2019)
• Biomarkers for Predicting Malignant Pleural Mesothelioma in a Mexican Population — G. Aguilar-Madrid, B. Pesch, et al. (2018)
• Prediagnostic detection of mesothelioma by circulating calretinin and mesothelin - a case-control comparison nested into a prospective cohort of asbestos-exposed workers — G. Johnen, K. Burek, et al. (2018)
• Assessment of miR-103a-3p in leukocytes-No diagnostic benefit in combination with the blood-based biomarkers mesothelin and calretinin for malignant pleural mesothelioma diagnosis — C. Jiménez-Ramírez, D. Gilbert Weber, et al. (2022)
• Combination of MiR-103a-3p and mesothelin improves the biomarker performance of malignant mesothelioma diagnosis — D.G. Weber, S. Casjens, et al. (2014)
• Development of an enzyme-linked immunosorbent assay for the detection of human calretinin in plasma and serum of mesothelioma patients — I. Raiko, I. Sander, et al. (2010)

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