Vandetanib Experience in a Patient with Ectopic Cushing Syndrome in Metastatic Medullary Thyroid Cancer

Abstract

Aim: Medullary thyroid cancer (MTC) constitutes 1-2% of all thyroid cancers. Ectopic Cushing's syndrome (ECS) developsin 0.6% of MTC cases. We wanted to present a case with metastatic MTC and ectopic Cushing's syndrome.
Case: A thirty-seven-year-old male patient was performed bilateral total thyroidectomy and left neck dissection in 2011. Histopathological findings revealed a metastatic MTC. He had a lung and neck lymph node metastases at the time of diagnosis. He received conventional chemotherapy and sunitinib treatment. He was a stable disease without treatment for the past two years. He had cushingoid appearance in October
2016. Laboratory results are shown in Table 1. RET mutation was negative. Bilateral adrenal glands and pituitary were normal. The colonoscopic examination detectedof the diverticulas. We diagnosed ECS due to metastatic MTC. Bilateral adrenalectomy was considered. However anesthesia was seen as high risk due to multiple rib fractures and operation could not be performed. Ketocanazole was given for ECS. Twenty days after treatment with ketoconazole, vandetanib treatment started. Urinary cortisol level was decreased to 14 mcg/day in the 6th months after vandetanib treatment. Potassium level was normal after 2 weeks of
treatment. In the first year of vandetanib treatment, a new metastatic lesion in the liver was detected with PET-CT. The patient is still under vandetanib treatment.
Conclusion: Ectopic Cushing syndrome due to metastatic MTC is very rare. In the literature, there are some data about the efficiacy of vandetanib treatment in metastatic MTC and ECS. In our case. progression with vandetanib treatment can be explained that it can not be used effective dose and time due to the side effects.