Current Consensus on I-131 MIBG Therapy / 대한핵의학회잡지

Metaiodobenzylguanidine (MIBG) is structurally similar to the neurotransmitter norepinephrine and specifically targets neuroendocrine cells including some neuroendocrine tumors. Iodine-131 (I-131)-labeled MIBG (I-131 MIBG) therapy for neuroendocrine tumors has been performed for more than a quarter-century. The indications of I-131 MIBG therapy include treatment-resistant neuroblastoma (NB), unresectable or metastatic pheochromocytoma (PC) and paraganglioma (PG), unresectable or metastatic carcinoid tumors, and unresectable or metastatic medullary thyroid cancer (MTC). I-131 MIBG therapy is one of the considerable effective treatments in patients with advanced NB, PC, and PG. On the other hand, I-131 MIBG therapy is an alternative method after more effective novel therapies are used such as radiolabeled somatostatin analogs and tyrosine kinase inhibitors in patients with advanced carcinoid tumors and MTC. No-carrier-aided (NCA) I-131 MIBG has more favorable potential compared to the conventional I-131 MIBG. Astatine-211-labeled meta-astatobenzylguanidine (At-211 MABG) has massive potential in patients with neuroendocrine tumors. Further studies about the therapeutic protocols of I-131 MIBG including NCA I-131 MIBG in the clinical setting and At-211 MABG in both the preclinical and clinical settings are needed.

Current Consensus on I-131 MIBG Therapy / 대한핵의학회잡지

Metaiodobenzylguanidine (MIBG) is structurally similar to the neurotransmitter norepinephrine and specifically targets neuroendocrine cells including some neuroendocrine tumors. Iodine-131 (I-131)-labeled MIBG (I-131 MIBG) therapy for neuroendocrine tumors has been performed for more than a quarter-century. The indications of I-131 MIBG therapy include treatment-resistant neuroblastoma (NB), unresectable or metastatic pheochromocytoma (PC) and paraganglioma (PG), unresectable or metastatic carcinoid tumors, and unresectable or metastatic medullary thyroid cancer (MTC). I-131 MIBG therapy is one of the considerable effective treatments in patients with advanced NB, PC, and PG. On the other hand, I-131 MIBG therapy is an alternative method after more effective novel therapies are used such as radiolabeled somatostatin analogs and tyrosine kinase inhibitors in patients with advanced carcinoid tumors and MTC. No-carrier-aided (NCA) I-131 MIBG has more favorable potential compared to the conventional I-131 MIBG. Astatine-211-labeled meta-astatobenzylguanidine (At-211 MABG) has massive potential in patients with neuroendocrine tumors. Further studies about the therapeutic protocols of I-131 MIBG including NCA I-131 MIBG in the clinical setting and At-211 MABG in both the preclinical and clinical settings are needed.

Extremity radioactive iodine uptake on post-therapeutic whole body scan in patients with differentiated thyroid cancer

Objective[s]: we investigated a frequency of lower extremity uptake on the radioactive iodine [RAI] whole body scan [WBS] after RAI treatment in patients with differentiated thyroid cancer, in order to retrospectively examine whether or not the frequency was pathological

Methods: this retrospective study included 170 patients with thyroid cancer, undergoing RAI treatment. Overall, 99r [58%] and 71 [42%] patients received single and multiple RAI treatments, respectively. Post-therapeutic WBS was acquired after 3 days of RAI administration. For patients with multiple RAI treatments, the WBS of their last RAI treatment was evaluated. Lower extremity uptake on post-therapeutic WBS was classified into 3 categories: bilateral femoral uptake [type A], bilateral femoral and tibia uptake [type B], and uptake in bilateral upper and lower extremities [type C]. Then, the patients with RAI uptake in the lower extremities on WBS were analyzed with clinical parameters

Results: overall, 99 patients [58%] had the extremity uptake on their posttherapeutic RAI WBS. As the results indicated, 42, 53, and 4 patients had type A, type B, and type C uptakes, respectively. Lower extremity uptake was significantly associated with younger age, not only in subjects with multiple RAI treatments but also in all the patients [P<0.05]. Accumulation in patients with multiple RAI treatments was more frequent than patients with single RAI treatment [P<0.05]. Lower extremity uptake was not associated with counts of the white blood cell count, hemoglobin level, platelet count, estimated glomerular filtration rate, effective half-time of RAI, serum TSH level, and anti-Tg concentration

Conclusion: about half of the patients had lower extremity uptake on the posttherapeutic RAI WBS, especially younger patients and those with multiple courses of RAI treatment. Bilateral lower extremity's RAI uptake on the posttherapeutic WBS should be considered as physiological RAI distribution in bone marrow

Thyroid hormone replacement one day before [131]I therapy in patients with well-differentiated thyroid cancer

The current study aimed to determine the efficacy of radioiodine-131 [131I] ablation therapy with thyroid hormone replacement one day before [131]I administration in patients with well-differentiated thyroid cancer [DTC]. This retrospective study included 29 patients who underwent [131]I therapies twice for DTC during 6-12 months. Since all the patients obviously had residual lesions by their serum thymoglobulin levels or their scintigrams at the first therapies, they underwent the second [131]I therapies without diagnostic scintigraphy after the first therapies. After confirming the sufficient elevation of TSH concentration, thyroid hormone replacement was resumed one day before [131]I administration [3.7-7.4GBq]. The ablation rate of thyroid remnant at the first [131]I therapy was evaluated by comparing [131]I post-therapeutic images of the two treatments. Three patients were administrated thyroid hormone after [131]I therapy because of insufficient TSH concentration under thyroid hormone withdrawal. In the remaining 26 patients, 41 thyroid remnant accumulations were detected in all 26 patients at the first [131]I therapy. Based on the second [131]I post-therapeutic images, successful ablation was confirmed in 24 of 26 patients [92.3%] and 38 of 41 sites [92.7%], which was comparable with historically reported ablation rates. Thyroid hormone replacement one day before [131]I therapy could provide a sufficiently high ablation rate in patients with DTC