Medullary Thyroid Carcinoma Preferentially Secreting Procalcitonin

Authors and affiliations:
Maria João Bugalho 1,2,3, Deolinda Madureira 4, Rita Domingues 2, Teresa Pereira 5 and Luísa Cortez 6

1 Endocrinology Service, Portuguese Institute of Oncology Francisco Gentil EPE, Lisbon, Portugal.

2 Research Unit of Molecular Pathobiology, Portuguese Institute of Oncology Francisco Gentil EPE, Lisbon, Portugal.

3 University Clinic of Endocrinology, Faculty of Medical Sciences, Nova University of Lisbon, Lisbon, Portugal.

4 Laboratory of Endocrinology, Portuguese Institute of Oncology Francisco Gentil EPE, Lisbon, Portugal.

5 Pathological Anatomy Service, Portuguese Institute of Oncology Francisco Gentil EPE, Lisbon, Portugal.

6 Endocrinology Service, Hospital Curry Cabral EPE, Lisbon, Portugal.

Abstract:
Abstract Background: Calcitonin (CT) is a useful pre and postoperative tumor marker for management of medullary thyroid cancer (MTC). A few cases of non-secreting carcinomas have been reported. Case presentation: A 55-yr-old man with multinodular goiter was diagnosed with MTC after a total thyroidectomy. Post operative basal and pentagastrin stimulated serum CT levels were normal (<10 pg/ml). Additionally, molecular analysis of RET (germline and tumoral DNA) revealed no mutations. Four years after surgery, there was evidence of recurrence in the left thyroid bed, lymph node enlargement within the right lung hilum and liver metastases. Serum calcitonin was no higher than 50 pg/ml. Factors able to justify erroneous calcitonin results were excluded. Contrasting with the inappropriately low levels of CT, increasingly high levels of proCT and CEA paralleled disease progression while CT remained stable. Tumor reduction (partial response) under treatment with Sunitinib was accompanied by a remarkable decrease of proCT and CEA. Conclusions: CT is not always the predominant product of the calcitonin gene in the circulation of patients with MTC. In a few cases, as illustrated herein, proCT might have a higher accuracy for diagnosis and follow-up. Impaired proteolytic cleavage of the proCT is a possible explanation for this finding. Measurement of proCT is suggested in apparently non-secreting MTC cases.

Journal:
Thyroid

Link:
http://online.liebertpub.com/doi/abs/10.1089/thy.2013.0664