Search

Objective: Our study aimed to analyse temporal trends in radioactive iodine (RAI) treatment for thyroid cancer over the past decade; to analyse key factors associated with clinical decisions in RAI dosing; and to confirm lower activities of RAI for low-risk patients were not associated with an increased risk of recurrence. Methods: Retrospective analysis of 1,323 patients who received RAI at a quaternary centre in Australia between 2008 and 2018 was performed. Prospectively collected data included age, gender, histology, and American Joint Committee on Cancer stage (7th ed). American Thyroid Association risk was calculated retrospectively. Results: The median activities of RAI administered to low-risk patients decreased from 3.85 GBq (104 mCi) in 2008–2016 to 2.0 GBq (54 mCi) in 2017–2018. The principal driver of this change was an increased use of 1 GBq (27 mCi) from 1.3% of prescriptions in 2008–2011 to 18.5% in 2017–2018. In patients assigned as low risk per ATA stratification, lower activities of 1 GBq or 2 GBq (27 mCi or 54 mCi) were not associated with an increased risk of recurrence. In patients assigned to intermediate- or high-risk categories who received RAI as adjuvant therapy, there was no difference in risk of recurrence between 4 GBq (108 mCi) and 6 GBq (162 mCi). Conclusions: Our data demonstrate an evolution of RAI activities consistent with translation of ATA guidelines into clinical practice. Use of lower RAI activities was not associated with an increase in recurrence in low-risk thyroid cancer patients. Our data also suggest lower RAI activities may be as efficacious for adjuvant therapy in intermediate- and high-risk patients.

Context Hyperglucagonemia in the absence of glucagonomas is rare. Biallelic-inactivating mutations in the glucagon receptor gene (GCGR) cause glucagon cell hyperplasia and neoplasia (GCHN), also termed Mahvash syndrome. Here, we report the first case to our knowledge of GCHN presenting with hypercalcemia and demonstrate a unique relationship between calcium and α-cell hyperplasia. Case Description A 47-year-old man presented with severe PTH-independent hypercalcemia, 13.95 mg/dL (3.48 mmol/L). Imaging and extensive pathology tests yielded no conclusive cause. Glucagon levels >300 times the upper limit of normal were discovered. Subtotal pancreatectomy identified α-cell hyperplasia and neoplasia with metastatic disease in lymph nodes. Genomic analysis confirmed a homozygous missense variant in GCGR (Asp63Asn). This is a previously described pathologic variant and has a known association with GCHN. Conclusions Inactivating mutations of the glucagon receptor gene lead to nonfunctional hyperglucagonemia and are associated with GCHN. Homozygous or compound heterozygous GCGR mutations are associated with α-cell hyperplasia, a known precursor to pancreatic neuroendocrine tumors that can metastasize. Hypercalcemia is an unreported consequence of GCHN with an unclear mechanism.

Pheochromocytoma (PC) is a neuroendocrine tumor that originates from chromaffin cells of the adrenal medulla. The production of catecholamines, including epinephrine, norepinephrine and dopamine, may lead to haemodynamic instability. Over 30 % of PCs are associated with germline mutations, including re-arranged in transfection (RET) mutations seen in multiple endocrine neoplasia type 2 (MEN2) syndromes. Around 40 % of individuals with MEN2 develop PC, though it is rarely the presenting feature. Compared to sporadic PC, MEN2-associated PC is more likely to be epinephine secreting and demonstrate bilateral adrenal involvement, and is less likely to be malignant. The diagnosis of PC requires clinical suspicion and biochemical testing, followed by imaging studies. Novel nuclear medicine modalities, including FDG positron emission tomography (PET) and 68Ga DOTATATE PET have added to the conventional techniques of 123 I-metaiodobenzylguanindine (MIBG) scintigraphy, computer tomography and magnetic resonance imaging. Treatment of PC is surgical and requires peri-operative alpha and, frequently, beta blockade. Novel surgical techniques, such as adrenal sparing surgery and a laparoscopic approach, have decreased peri-operative morbidity. Surveillance for PC is life long, due to the risk of metastatic disease.