Clinical efficacy of first and second series of peptide receptor radionuclide therapy in patients with neuroendocrine neoplasm: a cohort study.

OBJECTIVES: Peptide receptor radionuclide therapy (PRRT) is an established treatment for metastatic neuroendocrine neoplasms (NEN). However, only limited data exists for the effect of multiple series of PRRT. The aim of this study was to investigate PFS and OS inNEN patients treated with multiple series of PRRT conforming to the ENETS treatment protocol. METHODS: We included all patients with gastrointestinal (GI), pancreatic and bronchopulmonary (BP) NEN treated with PRRT from 2008 to 2018. We used Kaplan-Meier estimation to evaluate PFS and OS with subgroup analysis of primary tumor, Ki67-index, type of radioisotope and number of PRRT series. RESULTS: 133 patients (female/male 61/72) were included, median age 70 (interquartile range 64-76) years. GI-NEN comprised 62%, pancreatic 23% and BP 11%. Median Ki67-index was 5%. After first PRRTG1- and G2-tumors had PFS of 25 and 22 months, compared to 11 months in G3-NENs (p < .05) and PFS was longer in G1/G2 GI-NENs than BP-NEN (30vs. 12 months, p < .05). After retreatment with a second series of PRRT, the overall PFS (G1-G3) was 19 months, with G1- and G2-tumors having the highest PFS of 19 and 22 months, respectively. Overall, the GI and BP tumors had an OS of 54 and 51 months. CONCLUSIONS: PRRT is an effective therapy with long-term PFS and OS, especially in G1 and G2 NENs, and with better prognosis in GI-NEN compared with BP-NENs. OS and PFS was shorter after the second series of PRRT compared with the first, however results were still encouraging.

Clinical value of 11C-methionine positron emission tomography in persistent primary hyperparathyroidism-A case report with a mediastinal parathyroid adenoma.

INTRODUCTION: Primary hyperparathyroidism (PHPT) is a common endocrine disorder caused by pathologic growth of one or more of the parathyroid glands. Parathyroidectomies (PTX) in patients with PHPT are procedures with low morbidity, few complications, and a high cure rate. However, the parathyroid glands may be found at various anatomical locations and occasionally they are intrathoracic. CASE PRESENTATION: We present a 57-year-old patient with PHPT. Before the first and second operation, the preoperative imaging indicated pathologic parathyroid tissue in the neck. Due to postoperative persistent hypercalcemia we performed a 11C-methionine positron emission tomography (11C-MET-PET/CT). The scan showed a focus with increased activity in the mediastinum. Due to persistent disease, an ectopic parathyroid gland in the mediastinum was suspected. At a third operation, the parathyroid adenoma was resected through an anterolateral thoracotomy. Biochemical values normalized and bone mineral density improved postoperatively. Hence, an ectopic localization of a parathyroid gland should be considered during the preoperative planning of a PTX, especially in the re-operative setting. A multidisciplinary effort is necessary to address an intrathoracic adenoma. CONCLUSION: Ectopic parathyroid glands should be suspected when positive sestaMIBI uptake is seen in the mediastinum and other types of imaging (e.g. contrast enhanced CT scan or PET-CT) may confirm the finding of an ectopic parathyroid adenoma. From the present case and previous studies we found 11C-MET-PET/CT valuable in difficult PHPT cases.