Endocrine Abstracts

Introduction: Multiple endocrine neoplasia type 2B (MEN 2B) is an aggressive disorder characterized by medullary thyroid cancer (MTC) and pheochromocytoma. Peptide receptor radionuclide therapy (PRRT) with 177Lu-DOTATATE is an effective new treatment for inoperable or metastatic neuroendocrine tumors (NETs). Hematologic problems, myelodysplastic syndrome or leukemia can be seen after alkylating agent and peptide receptor radionuclide therapy treatments. We present metastatic meduller thyroid cancer patient with MEN 2B who developed acute leukemia after treatment with 177 Lu-labeled peptide receptor radionuclide.

Case: 28-year-old female was diagnosed with MEN 2B (thyroid medullary carcinoma, bilateral pheochromocytoma, and mucosal neurinoma) in 2015. Bilateral adrenalectomy and bilateral thyroidectomy with neck dissection was performed. The patients RET gen mutation was heterozygote positive. Liver biopsy for a liver mass showed metastasis of medullary thyroid carcinoma. F18-FDG-PET-CT revealed metastases in liver, lungs, and bone therefore she received alkylating chemotherapy of 6-cycles. ⁶⁸Ga-labeled somatostatin analogue PET/CT was revealed progression in metastatic lesions(somatostatin receptor positive) and increase in calcitonin levels after 12 months from the last cycle of chemotherapy. Six doses of Lu-177 DOTATATE was administered. After 9 months from the last dose of Lu-177 DOTATATE treatment progression in metastatic lesions and increase in calcitonin levels occurred and a new treatment was planned. However, her blood count revealed pancytopenia and bone marrow aspiration revealed promyelocytic cells. Genetic tests and flow cytometry analysis was consistent with acute promyelocytic leukemia (AML M3). Chemotherapy was planned for leukemia after ATRA treatment.

Conclusion: A decrease in bone marrow reserve, more rarely myelodysplastic syndrome (MDS) and leukemia may occur after PRRT. As with our patient, the risk of MDS increases when alkylating agents and PRRT are used together. Researchers state that acute leukemia (AL) occurred after a median follow-up of 55 months after first therapy (range 32–125 months). In our patient, acute promyelocytic leukemia occurred 18 months after the first PRRT treatment.