Prediagnostic detection of mesothelioma by circulating calretinin and mesothelin - a case-control comparison nested into a prospective cohort of asbestos-exposed workers

Abstract

Malignant mesothelioma (MM) is strongly associated with a previous asbestos exposure. To improve timely detection of MM in asbestos workers, better screening tools - like minimally-invasive biomarkers - are desirable. Between 2008 and 2018 2,769 patients with benign asbestos-related diseases were recruited to participate in annual screens. Using a nested case-control design the protein markers calretinin and mesothelin were determined by enzyme-linked immunosorbent assays in prediagnostic plasma samples of 34 MM cases as well as 136 matched controls from the cohort. Conditional on a pre-defined specificity of 98% for calretinin and 99% for mesothelin the markers reached individual sensitivities of 31% and 23%, respectively, when including the incident cases with samples taken between one and 15 months before diagnosis. The combination of both markers increased the sensitivity to 46% at 98% specificity. Marker complementation increased with earlier sampling. The marker combination improves the sensitivity of the individual markers, indicating a useful complementation and suggesting that additional markers may further improve the performance. This is the first prospective cohort study to evaluate a detection of MM by calretinin and its combination with mesothelin up to about a year before clinical diagnosis. Whether an earlier diagnosis will result in reduced mortality has yet to be demonstrated.

Figure 1

Study design and characteristics of the MoMar cohort. 2,769 asbestos-exposed workers with non-malignant asbestos-associated diseases participated in the study. Over a period of ten years, patients were invited annually for a medical exam and blood sampling. The patients participated up to ten times in the serial exams. Samples were stored in a biobank. At the completion of recruitment, incident MM cases were matched 1:4 to controls from the cohort, using a nested design, and biomarkers were determined.

Figure 2

Distribution of marker concentrations in cases and controls. Concentrations of (A) calretinin (ng/ml) and (B) mesothelin (nM) in prediagnostic plasma samples of 31 MM cases and 136 matched controls. P-values were obtained from the two-sided Wilcoxon rank-sum test. Whiskers represent the minimum and maximum.

Figure 3

ROC analysis of calretinin, mesothelin, and the combination of both markers for the 1–44 months interval. ROC curves and AUC values (confidence intervals are listed in Table 3) of the individual and combined markers, based on 31 MM cases and 136 controls. All of the samples are included that have been obtained 1–44 months before diagnosis. The marker combination is based on a “best case” sequential combination.

Figure 4

ROC analysis of calretinin, mesothelin, and the combination of both markers for the 1–15 months interval. ROC curves and AUC values (confidence intervals are listed in Table 3) of the individual and combined markers, based on 26 MM cases and 136 controls. Only samples are included that have been obtained 1–15 months before diagnosis. The marker combination is based on a “best case” sequential combination.

Figure 5

Venn diagram of all eligible MM cases of the cohort and correlation with marker results. A total of 12 MM tumors in 31 eligible cases were detected at a specificity of 98%. Calretinin detected eight and mesothelin six tumors, with two tumors detected by both markers. MM subtypes are indicated. The three sarcomatoid MM are labeled red, the six biphasic MM green, the 19 epithelioid MM blue, and the three MM without known histology grey. All cases within the 1–44 months interval between sample collection and diagnosis are shown, the cases within the 1–15 months interval are highlighted by a thick bordering.