A new case report demonstrates success in employing selpercatinib to treat a 62-year-old man with ectopic Cushing’s syndrome due to medullary thyroid carcinoma (MTC). The case report, published in Current Oncology, notes that the patient’s Cushing’s features had resolved after 6 months of treatment. After another 6 months, his s-calcitonin had normalized and there was significant tumor volume reduction.

“Patients with [MTC] and ectopic Cushing’s syndrome have a worse prognosis compared to patients with [MTC] but without hypercortisolism,” the authors wrote.

“It is therefore of great importance to detect patients with [MTC] who develop ectopic Cushing’s syndrome and to start cortisol-lowering medical treatment without delay.”

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The case with MTC and Cushing’s syndrome was placed on treatment with metyrapone and hydrocortisone upon the diagnosis of Cushing’s. After a genetic study revealing an oncogenic mutation in exon 16 of the RET gene, treatment with selpercatinib twice daily was started.

Despite having lymph node metastases at that point, after 6 months Cushing’s syndrome was resolved and his s-calcitonin level decreased to 3.5 pmol/L (normal is <3 pmol/L) and the metastases were reduced in size.

Six months later, his s-calcitonin was normal at 1.5 pmol/L and the tumor volume was significantly reduced. Metyrapone and hydrocortisone were discontinued, with no recurrence of hypercortisolism. However, due to adrenal insufficiency, hydrocortisone replacement was restarted.

At 18 months, the patient was in remission and without significant side effects. The authors concluded that selpercatinib could be a promising treatment option for patients with MTC and ectopic Cushing’s syndrome, particularly when other treatments have failed.  


Ragnarsson O, Piasecka M, Hallqvist, A. Successful treatment with selpercatinib for ectopic Cushing’s syndrome due to medullary thyroid cancer. Curr. Oncol. Published online May 12, 2022. doi:10.3390/curroncol29050282