Endocrine Abstracts

Introduction: Medullary thyroid carcinoma (MTC) constitutes 3.5-5% of all thyroid cancers. Routine biochemical diagnostics include determination of calcitonin (CT), procalcitonin (PCT) and carcinoembryonic antigen (CEA). XIAP (X-linked inhibitor of apoptosis protein) and survivin belong to the family of proteins – inhibitors of apoptosis (IAP). Using tissue microarrays, the expression levels of XIAP and survivin were tested in patients with medullary thyroid cancer. The study showed different expression of these biomarkers in patients with MTC at different stages of the disease. The clinical evaluation of the determination of these two proteins in blood in patients with medullary thyroid cancer has not been evaluated.

Materials and Methods: Thirty-four patients with MTC were included in the study. Patients were divided into two groups. Patients with confirmed active MTC (n=15) and patients with confirmed MTC in the stable phase, without recurrence or metastasis (n=19). The control group consisted of 40 healthy subjects. Serum CT and PCT levels were determined by the CLIA immunoassay. The concentration of CEA was determined by IRMA immunoassays, and the concentration of XIAP and survivin were determined in plasma by ELISA immunoassay.

Results: Levels of the tested biomarkers were assessed in patients with MTC in the active form of the disease, in patients with stable MTC and in the control group. Statistically significant differences were found between the study groups. The study groups were compared with each other: XIAP: MTC (active form) vs. control group: P=0.797; Survivin: MTC (active form) vs. control group: P=0.857, XIAP: MTC (stable form) vs. control group: P=0.793, and Survivin: MTC (stable form) vs. control group: P=0.844. ROC curves were used to compare the biomarkers studied in the group of patients with MTC (active form) vs. the group of healthy subjects. AUC (95%CI): XIAP 0.477 (0.296;0.657; P=0.866), Survivin 0.483 (0.302;0.664; P=0.951); CT 0.940 (0.857;1.203; P<0.001); PCT 1.000 (P<0.001); CEA 0.855 (0.704;1.004; P<0.001).

Conclusion: Determination of concentrations of new biomarkers: XIAP and survivin in the diagnostics of MTC can complement biochemical diagnosis in this group of patients.