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Endocrine Abstracts (2023) 92 PS2-17-04 | DOI: 10.1530/endoabs.92.PS2-17-04

ETA2023 Poster Presentations Thyroid Cancer Diagnosis 2 (9 abstracts)

PRO-gastrin-releasing peptide as an additional screening marker in the diagnostic work up for medullary thyroid carcinoma

Leonoor Schonebaum 1 , Mathé van Balkum 1 , W. Edward Visser 2 , Sjoerd van den Berg 3 & Robin Peeters 4

1Academic Center for Thyroid Diseases, Department of Internal Medicine, Rotterdam, Netherlands; 2Erasmus Medical Center, Academic Center for Thyroid Diseases, Department of Internal Medicine, Academic Center for Thyroid Diseases, Rotterdam, Netherlands; 3Erasmus MC, University Medical Center, Rotterdam, The Netherlands, Department of Clinical Chemistry and Department of Internal Medicine, Erasmus MC, University Medical Centre, Rotterdam, The Netherlands, Department of Clinical Chemistry, Erasmus MC, University Medical Center, Rotterdam, The Netherlands, Netherlands; 4Academic Center for Thyroid Diseases, Department of Endocrinology, Erasmus, Department of Internal Medicine, Rotterdam, Netherlands

Background: Patients with medullary thyroid carcinoma (MTC), a neuroendocrine tumour derived from the parafollicular C-cells, often present with metastasized disease. Survival strongly correlates with stage of disease at diagnosis, illustrating the need for early diagnosis. Calcitonin (CT), a well-established tumour marker for MTC, is limited by a high rate of false positives in the screening phase. Promising new markers for MTC are procalcitonin (PCT) and progastrin releasing peptide (proGRP). Where literature has proven non-inferiority for PCT, evidence is lacking for proGRP. Previous studies looking into proGRP had small sample size, mostly retrospective design and large variability in reported sensitivity, specificity and cut-off value. Therefore, the present study prospectively evaluated the clinical performance of proGRP in a large series of patients with pathology proven diagnosis of MTC vs other thyroid disease.

Methods: Serum samples from 278 patients that underwent total thyroidectomy for either benign thyroid disease (n =117), differentiated and other thyroid carcinomas (non-MTC) (n =137) or MTC (n =24) were collected before surgery. Serum proGRP and PCT concentrations were measured using Lumipulse G1200 (Fujirebio), CT was measured using Immulite 2000XPi (Siemens). Cut-offs for CT (10 pg/mL) and PCT (0.15 ng/mL) were based on literature. Cut-off for proGRP (100 pg/mL) was based on previous studies and validated in a local cohort.

Results: Median proGRP concentration (300.5; 69.7 – 1249.8) was significantly higher in MTC compared with benign thyroid disease (30.3; 23.9 – 38.2) and non-MTC (27.1; 21.9 – 34.5) (P < 0.001). Despite, having a good specificity of 99.6%, sensitivity of proGRP was low (70.4%). Therefore, proGRP did not perform better than CT in discriminating between MTC and benign thyroid disease or non-MTC in a screening setting. As expected, PCT performed as good as CT with a sensitivity off 100% and a specificity of 98.5% (CT sensitivity and specificity were 100% and 98.8% respectively). Combining proGRP and CT lead to a perfect specificity (100%), but decreased sensitivity even further (69.2%).

Conclusion: ProGRP alone does not perform better as a screening marker for MTC than CT. Furthermore, there is no added value of combining proGRP and CT in a two-step approach in cases where calcitonin concentration is inconclusive. This study supports the evidence in literature for PCT as a tumour marker in MTC, with PCT having clear advantages over CT given the better (pre-) analytical characteristics, such as inter-assay comparability and protein stability.

Volume 92

45th Annual Meeting of the European Thyroid Association (ETA) 2023

European Thyroid Association 

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