The role of procalcitonin and ProGRP in the follow-up of medullary thyroid carcinoma

Fernandes Andreia Martins; Micaela Batista; Silva Leandro Augusto; Elvas Ana Rita; Joana Couto; Martins Raquel G.; Jacinta Santos; Teresa Martins; Nuno Cunha; Fernando Rodrigues

doi:10.1530/endoabs.110.EP1429

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Endocrine Abstracts (2025) 110 EP1429 | DOI: 10.1530/endoabs.110.EP1429

ECEESPE2025 ePoster Presentations Thyroid (198 abstracts)

The role of procalcitonin and ProGRP in the follow-up of medullary thyroid carcinoma

Andreia Martins Fernandes ¹ , Micaela Batista ¹ , Leandro Augusto Silva ¹ , Ana Rita Elvas ¹ , Joana Couto ¹ , Raquel G. Martins ¹ , Jacinta Santos ¹ , Teresa Martins ² , Nuno Cunha ³ & Fernando Rodrigues ¹

Author affiliations

¹Portuguese Oncology Institute of Coimbra, Endocrinology Department, Coimbra, Portugal; ²Portuguese Oncology Institute of Coimbra, Coimbra, Portugal; ³Portuguese Oncology Institute of Coimbra, Laboratory Medicine Department, Coimbra, Portugal.

JOINT3803

Introduction: Calcitonin (Ctn) and carcinoembryonic antigen (CEA) are the primary tumour markers for medullary thyroid carcinoma (MTC) follow-up. Procalcitonin (ProCtn) and Progastrin-releasing Peptide (ProGRP) have been suggested as complementary markers for MTC, but the available data are still limited.

Aims: To evaluate the performance of ProCtn and ProGRP in post-surgical follow-up of MTC.

Materials and methods: Ctn, ProCtn, and ProGRP levels were measured at the last follow-up in a total of 85 patients: 21 controls with non-MTC thyroid disease and 64 patients with surgically treated MTC.

Results: In the control group, all patients had normal Ctn, ProCtn and ProGRP levels. Among the 64 patients with MTC, 35 (54.7%) were female, with a median age at diagnosis of 60 years. 46 patients had sporadic MTC and 18 hereditary MTC. The median follow-up time was 93.7 months. At the end of the follow-up, 25 patients (39.1%) showed no evidence of disease, 27 (42.2%) presented with biochemical evidence, and 12 (18.8%) exhibited structural evidence. ProCtn and Ctn (r = 0.939) and ProGRP and Ctn (r = 0.781) values were strongly correlated (P <0.001). Median ProCtn and ProGRP values differed across the groups - no evidence of disease, biochemical evidence, and structural evidence - at 0.06 ng/ml, 0.7 ng/ml, and 9.8 ng/ml for ProCtn, and 40.2 pg/ml, 62.6 pg/ml, and 536.6 pg/ml for ProGRP, respectively (P <0.001). No patients with structural disease had normal Ctn levels. Among those with elevated Ctn levels of ≤150 pg/ml, 10/20 (50%) had normal ProCtn, and 14/18 (77.8%) had normal ProGRP. None of the patients with elevated Ctn and normal ProCtn or ProGRP levels showed evidence of structural disease. The most accurate ROC-derived cut-off values for identifying structural disease were settled at 138.4 pg/ml for Ctn [AUC: 0.94 (95%CI 0.88-1), P <0.001] with 91.7% sensitivity, 82.7% specificity, 55% positive predictive value (PPV), and 97.7% negative predictive value (NPV); at 1.76 ng/ml for ProCtn [AUC: 0.96 (95%CI 0.9-1), P <0.001] with 90.9% sensitivity, 87.8% specificity, 62.5% PPV, and 97.7% NPV; and at 161.4 pg/ml for ProGRP [AUC:0.98 (95%CI 0.94-1), P <0.001] with 88.9% sensitivity, 97.9% specificity, 88.9% PPV, and 97.9% NPV.

Conclusions: ProCtn and ProGRP strongly correlate with Ctn in MTC follow-up. The established cut-off values for Ctn and ProCtn demonstrate excellent sensitivity and NPV in detecting structural disease, while ProGRP provides high specificity, PPV, and good sensitivity. These findings suggest that they may be promising complementary markers, but further research is needed to validate their clinical utility.