Polycythemia after vandetanib treatment in metastatic medullary thyroid carcinoma: A rare case report

Abstract

Medullary thyroid cancer is a neuroendocrine tumor of the thyroid gland and its frequency is 1–2% among all thyroid cancers. Their prognosis is poor with a 10-year survival rate of 40%. Vandetanib, an oral tyrosine kinase inhibitor, is an effective treatment option for unresectable locally advanced or metastatic medullary thyroid cancer. The most common side effects are hypertension, diarrhea, dermatitis, fatigue, nausea, and headache. It also has very important cardiac side effects such as QT prolongation and torsades de pointes. Erythrocytosis (polycythemia) is an abnormal elevation of hemoglobin and/or hematocrit levels in complete blood count. Smoking, obstructive sleep apnea and other pulmonary diseases are common secondary polycythemia causes. Besides; it is known that, some drugs such as recombinant erythropoiesis-stimulating agents, androgens and anabolic steroids can cause secondary polycythemia. To our knowledge, vandetanib associate polycythemia has been described in only one case previously. We present a case with metastatic medullar thyroid cancer who is under treatment with vandetanib and developed drug-related secondary polycythemia. This is the second case report in the literature.

Keywords

• Medullary thyroid cancer
• Vandetanib
• Polycythemia