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In this review, we explore the underlying molecular biology of medullary thyroid carcinoma (MTC) and its interplay with the host immune system. MTC is consistently driven by a small number of specific pathogenic variants, beyond which few additional genetic events are required for tumorigenesis. This explains the exceedingly low tumour mutational burden seen in most MTC, in contrast to other cancers. However, because of the low tumour mutational burden (TMB), there is a correspondingly low level of tumour-associated neoantigens that are presented to the host immune system. This reduces tumour visibility and vigour of the anti-tumour immune response and suggests the efficacy of immunotherapy in MTC is likely to be poor, acknowledging this inference is largely based on the extrapolation of data from other tumour types. The dominance of specific RET (REarranged during Transfection) pathogenic variants in MTC tumorigenesis rationalizes the observed efficacy of the targeted RET-specific tyrosine kinase inhibitors (TKIs) in comparison to multi-kinase inhibitors (MKIs). Therapeutic durability of pathway inhibitors is an ongoing research focus. It may be limited by the selection pressure TKI treatment creates, promoting survival of resistant tumour cell clones that can escape pathway inhibition through binding-site mutations, activation of alternate pathways, and modulation of the cellular and cytokine milieu of the tumour microenvironment (TME).

Aims: Recently, there have been attempts to improve prognostication and therefore better guide treatment for patients with medullary thyroid carcinoma (MTC). In 2022, the International MTC Grading System (IMTCGS) was developed and validated using a multi-institutional cohort of 327 patients. The aim of the current study was to build upon the findings of the IMTCGS to develop and validate a prognostic nomogram to predict recurrence-free survival (RFS) in MTC., Methods and Results: Data from 300 patients with MTC from five centres across the USA, Europe, and Australia were used to develop a prognostic nomogram that included the following variables: age, sex, AJCC stage, tumour size, mitotic count, necrosis, Ki67 index, lymphovascular invasion, microscopic extrathyroidal extension, and margin status. A process of 10-fold cross-validation was used to optimize the model's performance. To assess discrimination and calibration, the area-under-the-curve (AUC) of a receiver operating characteristic (ROC) curve, concordance-index (C-index), and dissimilarity index (D-index) were calculated. Finally, the model was externally validated using a separate cohort of 87 MTC patients. The model demonstrated very strong performance, with an AUC of 0.94, a C-index of 0.876, and a D-index of 19.06. When applied to the external validation cohort, the model had an AUC of 0.9., Conclusions: Using well-established clinicopathological prognostic variables, we developed and externally validated a robust multivariate prediction model for RFS in patients with resected MTC. The model demonstrates excellent predictive capability and may help guide decisions on patient management. The nomogram is freely available online at https://nomograms.shinyapps.io/MTC_ML_DFS/., (© 2024 The Authors. Histopathology published by John Wiley & Sons Ltd.)

Background: There remains uncertainty regarding the optimal extent of initial surgery and management of recurrent disease in medullary thyroid cancer (MTC). We aim to describe the patterns of disease recurrence and outcomes of the reoperative surgery in a cohort of consecutively treated patients at a specialized tertiary referral center., Patients and Methods: A retrospective cohort study of 235 surgically treated patients with MTC at a tertiary referral center was performed using prospectively collected data., Results: In the study period 1986-2022, 235 patients underwent surgery for MTC. Of these, 45 (19%) patients had reoperative surgery for cervical nodal recurrence at a median (range) 2.1 (0.3-16) years following the index procedure. After a median follow-up of 4 years, 38 (84%) patients remain free of structural cervical recurrence, although 15 (33%) underwent 2 or more reoperative procedures. No long-term complications occurred after reoperative surgery. Local cervical recurrence was independently predicted by pathologically involved nodal status (OR 5.10, P = .01) and failure to achieve biochemical cure (OR 5.0, P = .009). Local recurrence did not adversely affect overall survival and was not associated with distant recurrence (HR 0.93, P = .83). Overall survival was independently predicted by high pathological grade (HR 10.0, P = .002) and the presence of metastatic disease at presentation (HR 8.27, P = 0018)., Conclusion: Loco-regional recurrence in MTC does not impact overall survival, or the development of metastatic disease, demonstrating the safety of the staged approach to the clinically node-negative lateral neck. When recurrent disease is technically resectable, reoperative surgery can be undertaken with minimal morbidity in a specialized center and facilitates structural disease control., (© The Author(s) 2023. Published by Oxford University Press.)

Diffuse sclerosing variant papillary thyroid carcinoma (DS-PTC) is characterized clinically by a predilection for children and young adults, bulky neck nodes, and pulmonary metastases. Previous studies have suggested infrequent BRAF V600E mutation but common RET gene rearrangements. Using strict criteria, we studied 43 DS-PTCs (1.9% of unselected PTCs in our unit). Seventy-nine percent harbored pathogenic gene rearrangements involving RET, NTRK3, NTRK1, ALK, or BRAF; with the remainder driven by BRAF V600E mutations. All 10 pediatric cases were all gene rearranged (P = .02). Compared with BRAF V600E -mutated tumors, gene rearrangement was characterized by psammoma bodies involving the entire lobe (P = .038), follicular predominant or mixed follicular architecture (P = .003), pulmonary metastases (24% vs none, P = .04), and absent classical, so-called "BRAF-like" atypia (P = .014). There was no correlation between the presence of gene rearrangement and recurrence-free survival. Features associated with persistent/recurrent disease included pediatric population (P = .030), gene-rearranged tumors (P = .020), microscopic extrathyroidal extension (P = .009), metastases at presentation (P = .007), and stage II disease (P = .015). We conclude that DS-PTC represents 1.9% of papillary thyroid carcinomas and that actionable gene rearrangements are extremely common in DS-PTC. DS-PTC can be divided into 2 distinct molecular subtypes and all BRAF V600E -negative tumors (1.5% of papillary thyroid carcinomas) are driven by potentially actionable oncogenic fusions., (Crown Copyright © 2023. Published by Elsevier Inc. All rights reserved.)

Lymph node metastasis in thyroid cancer is common and associated with an increased risk of locoregional recurrence (LRR). Although therapeutic central neck dissection is well established, prophylactic central node dissection (pCND) for microscopic occult nodal involvement is controversial and recommendations are based on low-level evidence. The potential benefits of pCND such as reducing LRR and re-operation, refining staging, and improving surveillance are enthusiastically debated and the decision to perform pCND must be weighed up against the increased risks of complications., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: The diagnosis of follicular carcinoma is often difficult to make on pathological analysis, as the histological distinction from follicular adenoma rests solely on the presence of capsular or vascular invasion. Even on retrospective review of the histopathology after the disease biology has declared itself as malignant, the pathological diagnosis of malignancy may not be possible to make., Methods: We report three cases in which patients were initially diagnosed with benign follicular lesions, but re-presented with locally recurrent disease and a subsequent malignant disease course., Results: We describe a rare entity of follicular thyroid carcinoma that demonstrates a locally recurrent and eventually metastatic disease phenotype, despite persistently benign pathological findings., Conclusion: We highlight that if local recurrence occurs in discrete anatomical tissue planes, or in the thyroid bed following open total thyroidectomy for 'benign multinodular goitre', the possibility of this rare presentation of follicular thyroid carcinoma should be considered., (© 2023 The Authors. ANZ Journal of Surgery published by John Wiley & Sons Australia, Ltd on behalf of Royal Australasian College of Surgeons.)

Background: The 2015 American Thyroid Association (ATA) Guidelines permit thyroid lobectomy (TL) or total thyroidectomy in the management of low-risk papillary thyroid cancer (PTC). As definitive risk-stratification is only possible post-operatively, some patients may require completion thyroidectomy (CT) after final histopathological analysis., Methods: A retrospective cohort study of patients undergoing surgery for low-risk PTC in a tertiary referral centre was undertaken. Consecutive adult patients treated from January 2013 to March 2021 were divided into two groups (pre- and post-publication of ATA Guidelines on 01/01/2016). Only those eligible for lobectomy under rule 35(B) of the ATA Guidelines were included: Bethesda V/VI cytology, 1-4 cm post-operative size and without pre-operative evidence of extrathyroidal extension or nodal metastases. We examined rates of TL, CT, local recurrence and surgical complications., Results: There were 1488 primary surgical procedures performed for PTC on consecutive adult patients during the study period, of which 461 were eligible for TL. Mean tumour size ( P  = 0.20) and mean age ( P  = 0.78) were similar between time periods. The TL rate increased significantly from 4.5 to 18% in the post-publication period ( P < 0.001). The proportion of TL patients requiring CT (43 vs 38%) was similar between groups ( P  = 1.0). There was no significant change in complications ( P  = 0.55) or local recurrence rates ( P  = 0.24)., Conclusion: The introduction of the 2015 ATA Guidelines resulted in a modest but significant increase in the rate of lobectomy for eligible PTC patients. In the post-publication period, 38% of patients who underwent TL ultimately required CT after complete pathological analysis., Competing Interests: The authors declare that they have no relevant or material financial interests that relate to the research described in this paper., (© the author(s).)

Background: Pheochromocytoma and paraganglioma (PPGL) are rare neuroendocrine tumours, often associated with germline mutations that influence the disease biology and clinical course. We aimed to describe the genotypic and phenotypic characteristics of a consecutive series of PPGL patients and correlate mutation status with clinical outcomes., Methods: We performed a retrospective cohort study of all PPGL patients who presented to a tertiary referral centre between March 2005 and February 2022. Genotypic, phenotypic and follow-up data were analysed., Results: A total of 140 patients were included. Of these, 94 (67%) patients underwent genetic testing and a mutation was detected in 36 (38%) patients. Mutation presence was associated with younger age, smaller tumour size and bilateral adrenal tumours. Disease recurrence occurred at a median time of 5.4 (IQR 2.8-11.0) years after treatment in 21 (15%) patients, of which 14 (67%) had a mutation in a susceptibility gene. Recurrence pattern was influenced by mutation type; higher local recurrence risk for SDHA, SDHB, and MEN2B disease, and higher metastatic risk for SDHB, VHL and MEN2A disease. Recurrence occurred in three (3%) patients with mutation absence. Multivariate analysis revealed that age  ≤40 years and mutation presence were associated with increased risk of disease recurrence., Conclusions: Genotypic characteristics strongly influence disease presentation and recurrence risk, which may occur more than 5 years after initial treatment. Routine genetic testing of PPGL patients is warranted given the high prevalence of mutations, allowing for prognostication and tailored follow-up. In the presence of germline mutations, follow-up should be life-long., (© 2022. The Author(s) under exclusive licence to Société Internationale de Chirurgie.)

Background: The mortality rate is low in endocrine surgery, making it a difficult outcome to use for quality improvement in individual units. Lessons from population data sets are of value in improving outcomes. Data from the Australian and New Zealand Audit of Surgical Mortality (ANZASM) were used here to understand and elucidate potential systems issues that may contribute to preventable deaths., Methods: ANZASM data relating to 30-day mortality after thyroidectomy, parathyroidectomy, and adrenalectomy from 2009 to 2020 were reviewed. Mortality rates were calculated using billing data. Thematic analysis of independent assessor reports was conducted to produce a coding framework., Results: A total of 67 deaths were reported, with an estimated mortality rate of 0.03-0.07 per cent (38 for thyroidectomy (0.03-0.06 per cent), 16 for parathyroidectomy (0.03-0.06 per cent), 13 for adrenalectomy (0.15-0.33 per cent)). Twenty-seven deaths (40 per cent) were precipitated by clinically significant adverse events, and 18 (27 per cent) were judged to be preventable by independent ANZASM assessors. Recurrent themes included inadequate preoperative assessment, lack of anticipation of intraoperative pitfalls, and failure to recognize and effectively address postoperative complications. Several novel themes were reiterated, such as occult ischaemic heart disease associated with death after parathyroid surgery, unexpected intraoperative difficulties from adrenal metastasis, and complications due to anticoagulation therapy after thyroid surgery., Conclusion: This study represents a large-scale national report of deaths after endocrine surgery and provides insights into these rare events. Although the overall mortality rate is low, 27 per cent of deaths involved systems issues that were preventable following independent peer review., (© The Author(s) 2022. Published by Oxford University Press on behalf of BJS Society Ltd.)

In this article, we aim to describe our modern-day approach to total thyroidectomy, detailing the subtle refinements of our technique, as it has evolved over three decades and 21 000 cases. Since Delbridge's seminal paper in 2003, the major changes to our approach include a retrograde approach to the recurrent laryngeal nerve that allows dissection of the distal RLN from fascial bands within the ligament of Berry before medialisation of the thyroid lobe. Routine use of intraoperative nerve monitoring systems has increased our awareness of temporary neuropraxia, facilitated a reduction in the risk of bilateral RLN palsy and improved our identification and preservation of the external branch of the superior laryngeal nerve. The increasing use of advanced energy devices has been associated with a reduction in post-operative haematoma rates. We adopt a low threshold to parathyroid auto-transplantation, unless all glands are assessed to be clearly not at risk, and routinely supplement patients with Caltrate in the immediate post-operative period to minimize the risk of symptomatic hypocalcaemia. Ultimately, when we reflect on the subtle refinements that have contributed to improved outcomes, the fundamental principles of exposure and dissection that have evolved over decades remain the basis of our surgical approach and must continue to do so., (© 2022 Royal Australasian College of Surgeons.)

Background: Medullary thyroid carcinoma (MTC) can be targeted with tyrosine kinase inhibitors (TKIs). We aimed to report the outcomes of surgically managed MTC and to evaluate the impact of TKI use on patient survival., Methods: Consecutive patients treated surgically for MTC from 1986 to 2020 were identified from a prospectively collected database and were compared on the basis of stage at operation and TKI use. The primary outcome was overall survival (OS)., Results: Among 154 patients with a median age of 52 years, 40% presented with stage I/II disease and 60% presented with advanced (stage III or IV) disease. During a median follow-up of 7.5 years, 21% received TKIs for systemic disease. Those presenting with advanced disease were more likely to receive a TKI (31% vs. 7%), present with tumor invasion of the recurrent laryngeal nerve (RLN; 12% vs. 0%) and undergo reoperation (42% vs. 23%) compared with stage I-II patients. For the 11 patients found to have invasion of the RLN, five had preoperative functional vocal cords. Five-year OS was 84% for advanced disease, and stage IV patients who received TKIs had a median survival of 21 years, versus 15 years for those who did not (p = 0.3)., Conclusions: Surgery achieves long-term survival for patients with advanced disease, however these patients are at greater risk of requiring RLN resection due to invasion. A significant OS benefit was not seen for TKI use. For patients with local invasion, neoadjuvant TKI therapy may have a role in reducing local morbidity if confirmed to be of benefit in clinical trials., (© 2021. Society of Surgical Oncology.)

The debate regarding the surgical management of low-risk differentiated thyroid cancer (DTC) is ongoing. The recommended extent of surgery in DTC is based on an assessment of the predicted risk of recurrence and recent guidelines reflect an evolving philosophy of de-escalation of surgical management, informed by a growing understanding of the determinants of tumour biology and important prognostic factors. However, our current clinical and pathological risk stratification processes are imperfect and hence there is significant variation in clinical practice. Surgeons face the challenge of finding the balance between avoiding overtreatment, minimizing complications and providing adequate oncological management. This article discusses the nuances of the current management guidelines as well as the important considerations in preoperative decision making., (© 2021 Royal Australasian College of Surgeons.)

Background: Prophylactic central lymph node dissection (CLND) in papillary thyroid cancer (PTC) is controversial. We aimed to investigate if prophylactic CLND aids risk stratification and contributes to the decision for postoperative RAI ablation., Methods: Patients undergoing thyroidectomy for PTC and prophylactic CLND were identified from an endocrine surgical unit database. Pathology reports where reviewed for number and size of lymph nodes and patients stratified by risk according to the ATA guidelines., Results: 426 patients were identified with PTC ≤4 cm and prophylactic CLND. 96 patients (23%) had central lymph node metastasis (CLNM) that qualified them for the intermediate risk group. In 17 patients (4%), the CLNM data led to upgrading independently of other histopathological characteristics. Correcting for multiple variables, CLNM was an independent factor contributing to RAI treatment., Conclusion: Prophylactic CLND provides information to aid the selection of RAI ablation independent of primary cancer histology for risk stratification in 4% of patients. This benefit should be carefully balanced with the risk of CLND and patient treatment choice when deciding on management of PTC ≤4 cm., Competing Interests: Declaration of competing interestcoi The authors have no conflicts of interest., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: The occurrence of distant metastasis (DM) is the most important prognostic factor influencing survival outcomes in differentiated thyroid cancer (DTC). Identifying patients who are likely to develop DM and offering these cases more aggressive surgical approaches and I-131 therapy, is paramount to achieving the best possible outcomes. DM on presentation in DTC are uncommon, with an incidence of 1-9%. However, the incidence of DTC is rising and the disease affects a relatively young cohort of patients. The aims of this study were to investigate predictive factors in the development of DM by comparing a homogenous group of DTC patients with and without DM, and to illustrate the overall and disease-specific survival (DSS) rates of DTC patients presenting with DM., Methods: A matched case-control study of patients with DTC and DM was undertaken. The study group comprised a consecutive series of cases with DM treated in the period 1968-2014. Patients with DM at initial presentation were identified (DTC-DM group). A control group of patients without DM were matched based on age, gender, tumour size and histological subtype. The primary outcome measures were overall and disease-free survival. Secondary outcome measures were lymph node involvement (LNI), extra-thyroidal extension (ETE) of tumour and presence of BRAFV600E mutation identified on immunohistochemistry., Results: A total of 2547 patients with DTC were reviewed and of these 83 (3.26%) had DM at initial presentation. At 5 and 10 years, the overall survival rates for DTC-DM patients were 89.6% and 64%, respectively. The 5 and 10 year DSS rates for DTC-DM cases were 90.2% and 67.3%, respectively. When compared to the DTC group, the DTC-DM group had significantly higher rates of ETE (63% vs. 29.5%, P < 0.0001) and LNI (32.5% vs. 18.8%, P = 0.044). Among patients with papillary thyroid cancer (PTC), the presence of BRAFV600E mutation was significantly associated with DM (62.2% vs. 36.8%, P = 0.028)., Conclusion: ETE, LNI and BRAFV600E mutation in PTC are significant predictors for the development of distant metastatic disease., (© 2021 Royal Australasian College of Surgeons.)

Background: Post-operative management after phaeochromocytoma resection includes monitoring of blood pressure and blood sugar, and vigilance for haemorrhage. Guidelines recommend 24 h of continuous blood pressure monitoring, usually necessitating HDU/ICU admission. We hypothesised that most patients undergoing phaeochromocytoma resection do not require post-operative HDU/ICU admission. We aim to describe current Australian and New Zealand perioperative management of phaeochromocytoma and determine whether it is safe to omit HDU/ICU care for most patients., Methods: We collected retrospective data on patients undergoing excision of phaeochromocytoma in 12 centres around Australia and New Zealand between 2007 and 2019. Data collected included preoperative medical management, anaesthetic management, vasopressor support, HDU/ICU admission and complications., Results: A total of 223 patients were included in the study, 173 (77%) of whom were admitted to HDU/ICU post-operatively. The group of patients treated in ICU was similar to the group of patients treated on the ward in terms of demographic and tumour characteristics, and there were significant differences in the proportion of patients admitted to HDU/ICU between centres. Of patients admitted to ICU, 71 (41%) received vasopressor support. This was weaned within 24 h in 55 (77%) patients. Patients with larger tumours (> 6 cm) and a transfusion requirement are more likely to require prolonged inotropic support. Among patients admitted to the ward, there were no complications that required escalation of care., Conclusions: Although not widespread practice in Australia and New Zealand, it appears safe for the majority of patients undergoing minimally invasive resection of phaeochromocytoma to be admitted to the ward post-operatively.

Background: The landscape of patients with end-stage renal disease is changing with the increasing availability of kidney transplantation. In the near future, a less aggressive approach to treat secondary hyperparathyroidism might be beneficial. We report outcomes of parathyroidectomy for end-stage renal disease-related hyperparathyroidism comparing the outcomes of limited, subtotal, and total parathyroidectomy., Methods: We performed a retrospective analysis of prospectively collected data. Patients were divided into 3 parathyroidectomy subgroups: limited (<3 glands removed), subtotal (3-3.5 glands), and total (4 glands) parathyroidectomy. Primary outcome was serum levels of parathyroid hormone. Secondary endpoints were serum levels of calcium, phosphate, and alkaline phosphatase, postoperative complications, and persistent or recurrent disease rates., Results: In total, 195 patients were included for analysis of whom 13.8% underwent limited parathyroidectomy, 46.7% subtotal parathyroidectomy, and 39.5% total parathyroidectomy. Preoperative parathyroid hormone levels (pg/mL) were 471 (210-868), 1,087 (627-1,795), and 1,070 (475-1,632) for the limited, subtotal, and total parathyroidectomy groups, respectively (P < .001). A decrease in serum parathyroid hormone was seen in all groups; however, postoperative levels remained greater in the limited parathyroidectomy group compared to the subtotal and total parathyroidectomy groups (P < .001). Serum calcium, phosphate, and alkaline phosphatase levels decreased in all groups to within the reference range. In the limited parathyroidectomy group, persistent disease and recurrence occurred more frequently (P = .02 and P = .07, respectively)., Conclusion: Subtotal parathyroidectomy is the optimal strategy in an era with an increasing availability of kidney transplantation and improved regimens of dialysis. In this changing practice, the approach to parathyroid surgery, however, might shift to a less aggressive and patient-tailored approach., (Copyright © 2020 Elsevier Inc. All rights reserved.)

We investigated the prognostic value of a range of histologic parameters in medullary thyroid carcinoma (MTC) to design a grading system to predict overall survival. We assessed 76 patients with MTCs undergoing primary tumor resection for age, sex, tumor size, vascular space invasion, lymph node metastasis, multiple endocrine neoplasia type 2 (MEN2) status, mitotic count, Ki-67 proliferative index, spindled morphology, sheet-like growth pattern, coagulative necrosis, incipient necrosis, nuclear grade, multinucleation, prominent nucleoli, fibrosis, and amyloid deposition. In addition to the clinical features of age and the diagnosis of MEN2, the only histologic features that significantly predicted reduced overall survival were Ki-67 proliferative index, mitotic count, and the presence of coagulative necrosis. Using a combination of these 3 variables, we propose a 3-tiered grading system based solely on proliferative activity (Ki-67 proliferative index and mitotic count) and necrosis. There were 62 (82%) low-grade MTCs (low proliferative activity, no necrosis), 9 (12%) intermediate grade (low proliferative activity and necrosis present, or intermediate proliferative activity and no necrosis), and 5 (7%) high grade (intermediate proliferative activity and necrosis present, or high proliferative activity with or without necrosis). The mean overall survival was 193, 146, and 45 months, respectively (P=0.0001) for the 3 grades. The grading system remained prognostic when controlled for other factors associated with survival including age and known MEN2 syndrome. We conclude that this proposed grading system, which uses only a combination of proliferative activity (Ki-67 index, mitotic count) and coagulative necrosis, is a strong predictor of overall survival in MTC.

The incidence of thyroid cancer is rapidly increasing, mostly due to the overdiagnosis and overtreatment of differentiated thyroid cancer (TC). The increasing use of potent preclinical models, high throughput molecular technologies, and gene expression microarrays have provided a deeper understanding of molecular characteristics in cancer. Hence, molecular markers have become a potent tool also in TC management to distinguish benign from malignant lesions, predict aggressive biology, prognosis, recurrence, as well as for identification of novel therapeutic targets. In differentiated TC, molecular markers are mainly used as an adjunct to guide management of indeterminate nodules on fine needle aspiration biopsies. In contrast, in advanced thyroid cancer, molecular markers enable targeted treatments of affected signalling pathways. Identification of the driver mutation of targetable kinases in advanced TC can select treatment with mutation targeted tyrosine kinase inhibitors (TKI) to slow growth and reverse adverse effects of the mutations, when traditional treatments fail. This review will outline the molecular landscape and discuss the impact of molecular markers on diagnosis, surveillance and treatment of differentiated, poorly differentiated and anaplastic follicular TC.

Background: Papillary thyroid microcarcinoma is a subtype of thyroid cancer that may be managed with active surveillance rather than immediate surgery. Active surveillance decreases complication rates and may decrease health care costs. This study aims to analyze complication rates of thyroid surgery, papillary thyroid microcarcinoma recurrence, and survival rates. Additionally, the costs of surgery versus hypothetic active surveillance for papillary thyroid microcarcinoma are compared in an Australian cohort., Methods: Papillary thyroid microcarcinoma patients were included from a prospectively collected surgical cohort of patients treated for papillary thyroid cancer between 1985 and 2017. The primary outcomes were the complications of thyroid surgery, recurrence-free survival, overall survival, and cost of surgical treatment and active surveillance., Results: In a total of 349 patients with papillary microcarcinoma with a median age of 48 years (range, 18-90 years), the permanent operative complications rate was 3.7%. Postoperative radioactive iodine did not decrease recurrence-free survival (P = .3). The total cost of surgical treatment was $10,226 Australian dollars, whereas hypothetic active surveillance was at a yearly cost of $756 Australian dollars. Estimated cost of surgical papillary thyroid microcarcinoma treatment was equivalent to the cost of 16.2 years of active surveillance., Conclusion: Surgery may have a long-term economic advantage for younger Australian patients with papillary thyroid microcarcinoma who are likely to require more than 16.2 years of follow-up in an active surveillance scheme., (Copyright © 2019. Published by Elsevier Inc.)

Thyroid neoplasia is common and requires appropriate clinical workup with imaging and fine-needle aspiration (FNA) biopsy to evaluate for cancer. Yet, up to 20% of thyroid nodule FNA biopsies will be indeterminate in diagnosis based on cytological evaluation. Genomic approaches to characterize the malignant potential of nodules showed initial promise but have provided only modest improvement in diagnosis. Here, we describe a method using metabolic analysis by desorption electrospray ionization mass spectrometry (DESI-MS) imaging for direct analysis and diagnosis of follicular cell-derived neoplasia tissues and FNA biopsies. DESI-MS was used to analyze 178 tissue samples to determine the molecular signatures of normal, benign follicular adenoma (FTA), and malignant follicular carcinoma (FTC) and papillary carcinoma (PTC) thyroid tissues. Statistical classifiers, including benign thyroid versus PTC and benign thyroid versus FTC, were built and validated with 114,125 mass spectra, with accuracy assessed in correlation with clinical pathology. Clinical FNA smears were prospectively collected and analyzed using DESI-MS imaging, and the performance of the statistical classifiers was tested with 69 prospectively collected clinical FNA smears. High performance was achieved for both models when predicting on the FNA test set, which included 24 nodules with indeterminate preoperative cytology, with accuracies of 93% and 89%. Our results strongly suggest that DESI-MS imaging is a valuable technology for identification of malignant potential of thyroid nodules., Competing Interests: Competing interest statement: R.J.D., J.Z., E.A., W.Y., J.S., and L.S.E. are inventors on a provisional patent application owned by the Board of Regents of the University of Texas System and Baylor College of Medicine that relates to the use of mass spectrometry to diagnose thyroid cancer. L.S.E. and Nicholas Winograd are coauthors on a 2019 Q&A article.

Adrenocortical carcinoma (ACC) has high recurrence rates and poor prognosis with limited response to conventional cancer therapy. Recent contributions of high-throughput transcriptomic profiling identified microRNA-497 (miR-497) as significantly underexpressed, while lncRNA MALAT1 (metastasis-associated lung adenocarcinoma transcript 1) as overexpressed in ACC. miR-497 is located in the chromosomal region 17p13.1, in which there is a high frequency of loss of heterozygosity in ACC. We aim to investigate the interaction of miR-497 and MALAT1 in ACC and its functional roles in the process of tumourigenesis. In this study, we demonstrated miR-497 post-transcriptionally repressed MALAT1 while MALAT1 also competes for miR-497 binding to its molecular target, EIF4E (eukaryotic translation initiation factor 4E). We showed that overexpression of miR-497 and silencing of MALAT1 suppressed cellular proliferation and induced cell cycle arrest through downregulation of EIF4E expression. Furthermore, MALAT1 directly binds to SFPQ (splicing factor proline and glutamine rich) protein, indicating its multifaceted roles in ACC pathophysiology. This is the first study to identify the feedback axis of miR-497-MALAT1/EIF4E in ACC tumourigenesis, providing novel insights into the molecular functions of noncoding RNAs in ACC.

Background: Medullary thyroid carcinoma (MTC) presents a disproportionate number of thyroid cancer deaths due to limited treatment options beyond surgery. Gain-of-function mutations of the human REarranged during Transfection ( RET ) proto-oncogene have been well-established as the key driver of MTC tumorigenesis. RET has been targeted by tyrosine kinase inhibitors (TKIs), such as cabozantinib and vandetanib. However, clinical results have been disappointing, with regular dose reductions and inevitable progression. This study aimed to identify RET-regulated microRNAs (miRNAs) and explore their potential as novel therapeutic targets. Methods: Small RNA sequencing was performed in MTC TT cells before and after RET inhibition to identify RET-regulated miRNAs of significance. In vitro gain-of-function studies were performed to investigate cellular and molecular effects of potential miRNAs on cell phenotypes. Systemic delivery of miRNA in MTC xenografts using EDV™ nanocells, targeted to epidermal growth factor receptor on tumor cells, was employed to assess the therapeutic potential and possible modulation of TKI responses. Results: The study demonstrates the tumor suppressive role of a specific RET-regulated miRNA, microRNA-153-3p (miR-153-3p), in MTC. Targeted intravenous delivery of miR-153-3p impeded the tumor growth in MTC xenografts. Furthermore, combined treatment with miR-153-3p plus cabozantinib caused greater growth inhibition and appeared to reverse cabozantinib resistance. Mechanistically, miR-153-3p targets ribosomal protein S6 kinase B1 (RPS6KB1) of mTOR signaling and reduced downstream phosphorylation of Bcl-2 associated death promoter. Conclusion: This study provides evidence to establish systemic miRNA replacement plus TKIs as a novel therapeutic for patients with metastatic, progressive MTC.

Background: Adrenocortical carcinoma (ACC) is a rare endocrine cancer with treatments limited in efficacy for metastatic disease. New molecular targeted therapies have yet to improve patient outcomes. In contrast, established treatment regimens of adrenolytics and chemotherapy have demonstrated treatment benefit, although admittedly in a minority of patients. Identification of microRNAs (miRNAs) in patients responsive to adjuvant therapy may offer a means to sensitize patients with progressive disease to existing adjuvant regimens., Materials and Methods: Samples from primary ACC tumors of 10 Stage IV patients were examined for differentially expressed miRNAs between a "sensitive" and "resistant" cohort. Candidate microRNAs were restored via transfection in two functional ACC cell lines. Gain of function and effects on apoptosis and cell cycle were assessed., Results: microRNA-431 (miR-431) was underexpressed in patients with ACC with progressive disease undergoing adjuvant therapy. Restoration of miR-431 in vitro decreased the half maximal inhibitory concentrations of doxorubicin and mitotane, with markedly increased apoptosis. We found that a reversal of epithelial-mesenchymal transition underlies the action of miR-431 with doxorubicin treatment, with Zinc Finger E-Box Binding Homeobox 1 implicated as the molecular target of miR-431 in ACC., Conclusion: This is the first report of the potential of miRNA therapy to sensitize ACC to current established adjuvant therapy regimens, which may mitigate the resistance underlying treatment failure in patients with advanced ACC. Effective and well-studied methods of targeted miRNA delivery in existence hints at the imminent translatability of these findings., Implications for Practice: Adrenocortical carcinoma (ACC) is a rare endocrine cancer with outcomes not improving despite extensive research and new targeted therapies. Mitotane and etoposide/doxorubicin/cisplatin chemotherapy is trial validated for improved recurrence-free survival. However, a minority of patients experience sustained benefit. Significant side effects exist for this regimen, with patients often unable to attain target drug doses shown to give survival benefit. This preclinical study examines the role of microRNAs in sensitizing ACC to doxorubicin or mitotane. This study offers an important bridge between new and existing cancer treatments, offering an imminently translatable approach to the treatment of adrenocortical carcinoma., Competing Interests: Disclosures of potential conflicts of interest may be found at the end of this article., (© AlphaMed Press 2019.)

Background: Low-risk differentiated thyroid cancers may, according to the American Thyroid Association (ATA) 2015 guidelines, be managed initially with lobectomy. However, definitive risk categorization requires pathological assessment of the specimen, resulting in completion thyroidectomy being recommended when discordance between preoperative and postoperative staging occurs. This study sought to establish the expected rate of completion thyroidectomy in patients with papillary thyroid cancer (PTC) treated by lobectomy., Methods: Patients with PTC treated over 5 years (2013-2017 inclusive) and meeting the ATA criteria for lobectomy were identified from the prospectively developed database of a high-volume, university department of endocrine surgery. Concordance between the ATA initial and final recommendation, and the putative rate of completion thyroidectomy were calculated. Multivariable analysis was used to assess preoperative factors as predictors of the need for total thyroidectomy., Results: Of 275 patients with PTC who met ATA preoperative criteria for lobectomy there was concordance between this and the final recommendation in 158 (57·5 per cent) and discordance in 117 (43·5 per cent). Most common reasons for discordance were: angioinvasion (30·8 per cent), local invasion (23·9 per cent) or both (20·5 per cent). Four patients (1·5 per cent) had permanent hypoparathyroidism. On multivariable analysis, age, sex, tumour size and family history did not independently predict the final treatment required., Conclusion: Although many patients may be treated adequately with lobectomy, just under half would require completion thyroidectomy. Further work is needed on preoperative risk stratification but, before this, total thyroidectomy remains the treatment of choice for low-risk 1-4-cm PTC in the hands of high-volume thyroid surgeons who can demonstrate low complication rates.

Background: Adrenocortical carcinoma is a rare and heterogeneous malignancy with poor outcomes. Recent research has suggested that outcomes may be improved by centralization of care in specialist centres. We review our evolving 21-year experience in managing adrenocortical carcinoma with a view towards outcomes and lessons learnt., Methods: A retrospective study of patients treated in our specialist endocrine surgical unit over 21 years was undertaken., Results: Thirty-five patients were treated from diagnosis, 29 forming a primary study cohort. Additionally, seven patients were referred to us for quaternary care, forming a secondary study cohort. The European Network for the Study of Adrenal Tumours (ENSAT) stage and immunohistochemical marker Ki-67 index were strong prognostic indicators for survival., Conclusions: Early stage, complete resection and Ki-67 <10% are the best prognosticators for survival. Aggressive surgical resection at index operation and of recurrent oligometastatic disease along with multimodal adjuvant treatment has led to long-term survivors of patients with Stage 4 disease in our aggregate cohort., (© 2019 Royal Australasian College of Surgeons.)

Background: Since 2004, end-stage renal disease related hyperparathyroidism patients are treated mainly with cinacalcet, which ceased to be subsidized through the Australian Pharmaceutical Benefits Scheme in 2015. We aimed to investigate the impact of these changes on the treatment strategy in the Australian end-stage renal disease population., Methods: The following groups were formed according to the date of parathyroidectomy: A, before calcimimetics; B, during the era of calcimimetics; and C, after cinacalcet removal by the Australian Pharmaceutical Benefits Scheme. The primary outcome was time from start of dialysis to parathyroidectomy. Regression analysis was used to examine trends in parathyroidectomy rates., Results: Between 1998 and 2016, 195 parathyroidectomies were performed. Median time to referral was 69 (33-123), 67 (31-110) and 44 (23-102) months for groups A, B, and C, respectively (P = .55). Parathyroidectomy rates increased throughout the years (CI 0.09-1.13, R 2 =0.27, P = .02). A trend toward a dip in parathyroidectomy rates was seen during the era of cinacalcet (P = .08). Median preoperative parathyroid hormone levels increased significantly (842 [418-1,553] versus 1,040 [564-1,810] versus 1,350 [1,037-1,923] pg/mL, for groups A, B, and C, respectively [P < .01])., Conclusion: Parathyroidectomy rates seem to vary according to the availability of cinacalcet. This change in treatment strategy is accompanied with increased preoperative parathyroid hormone levels, reflecting delayed surgery and increased disease severity., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The gene CDC73 (previously known as HRPT2) encodes the protein parafibromin. Biallelic mutation of CDC73 is strongly associated with malignancy in parathyroid tumors. Heterozygous germline mutations cause hyperparathyroidism jaw tumor syndrome,which is associated with a high life-time risk of parathyroid carcinoma. Therefore loss of parafibromin expression by immunohistochemistry may triage genetic testing for hyperparathyroidism jaw tumor syndrome and be associated with malignant behavior in atypical parathyroid tumors. We share our experience that parafibromin-negative parathyroid tumors show distinctive morphology. We searched our institutional database for parathyroid tumors demonstrating complete loss of nuclear expression of parafibromin with internal positive controls. Forty-three parafibromin-negative tumors from 40 (5.1%) of 789 patients undergoing immunohistochemistry were identified. Thirty-three (77%) were external consultation cases; the estimated incidence in unselected tumors was 0.19%. Sixteen (37.2%) fulfilled World Health Organization 2017 criteria for parathyroid carcinoma and 63% had serum calcium greater than 3mmol/L. One of 27 (3.7%) noninvasive but parafibromin-negative tumors subsequently metastasized. Parafibromin-negative patients were younger (mean, 36 vs. 63 y; P<0.001) and had larger tumors (mean, 3.04 vs. 0.62 g; P<0.001). Not all patients had full testing, but 26 patients had pathogenic CDC73 mutation/deletions confirmed in tumor (n=23) and/or germline (n=16). Parafibromin-negative tumors demonstrated distinctive morphology including extensive sheet-like rather than acinar growth, eosinophilic cytoplasm, nuclear enlargement with distinctive coarse chromatin, perinuclear cytoplasmic clearing, a prominent arborizing vasculature, and, frequently, a thick capsule. Microcystic change was found in 21 (48.8%). In conclusion, there are previously unrecognized morphologic clues to parafibromin loss/CDC73 mutation in parathyroid tumors which, given the association with malignancy and syndromic disease, are important to recognize.

Medullary thyroid carcinoma (MTC) is an aggressive and rare cancer with limited treatment options for metastatic disease. Due to this, there is a need for a better understanding of MTC biology in the hope of improved treatments. One area of improved understanding of cancer biology is epigenetics. Epigenetics is defined as cellular processes which alter gene expression independent of changes in the primary DNA sequence. These processes include modifications such as DNA methylation, microRNA deregulation and post-translational histone modifications, all of which have been implicated in tumorigenesis of MTC. Transcription of the main driver of MTC - the REarranged during Transfection (RET) proto-oncogene can also be modulated by epigenetic alterations. This review will present a review of MTC and its epigenetic links with a particular focus on targeting epigenetic mechanisms as novel therapeutic strategies., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Background: Integrity of the recurrent laryngeal nerve (RLN) and the external branch of the superior laryngeal nerve (EBSLN) can be checked by intraoperative nerve monitoring (IONM) after visualization. The aim of this study was to determine the prevalence and nature of voice dysfunction following thyroid surgery with routine IONM., Methods: Thyroidectomies were performed with routine division of strap muscles and nerve monitoring to confirm integrity of the RLN and EBSLN following dissection. Patients were assessed for vocal function before surgery and at 1 and 3 months after operation. Assessment included use of the Voice Handicap Index (VHI) 10, maximum phonation time, fundamental frequency, pitch range, harmonic to noise ratio, cepstral peak prominence and smoothed cepstral peak prominence., Results: A total of 172 nerves at risk were analysed in 102 consecutive patients undergoing elective thyroid surgery. In 23·3 per cent of EBSLNs and 0·6 per cent of RLNs nerve identification required the assistance of IONM in addition to visualization. Nerve integrity was confirmed during surgery for 98·8 per cent of EBSLNs and 98·3 per cent of RLNs. There were no differences between preoperative and postoperative VHI-10 scores. Acoustic voice assessment showed small changes in maximum phonation time at 1 and 3 months after surgery., Conclusion: Where there is routine division of strap muscles, thyroidectomy using nerve monitoring confirmation of RLN and EBSLN function following dissection results in no clinically significant voice change.

To easily edit the genome of naïve human embryonic stem cells (hESC), we introduced a dual cassette encoding an inducible Cas9 into the AAVS1 site of naïve hESC (iCas9). The iCas9 line retained karyotypic stability, expression of pluripotency markers, differentiation potential, and stability in 5iLA and EPS pluripotency conditions. The iCas9 line induced efficient homology-directed repair (HDR) and non-homologous end joining (NHEJ) based mutations through CRISPR-Cas9 system. We utilized the iCas9 line to study the epigenetic regulator, PRC2 in early human pluripotency. The PRC2 requirement distinguishes between early pluripotency stages, however, what regulates PRC2 activity in these stages is not understood. We show reduced H3K27me3 and pluripotency markers in JARID2 2iL-I-F hESC mutants, indicating JARID2 requirement in maintenance of hESC 2iL-I-F state. These data suggest that JARID2 regulates PRC2 in 2iL-I-F state and the lack of PRC2 function in 5iLA state may be due to lack of sufficient JARID2 protein.

The search for targeted novel therapies for cancer is ongoing. MicroRNAs (miRNAs) display a number of characteristics making them an attractive and realisable option. In this review, we explore these applications, ranging from diagnostics, prognostics, disease surveillance, to being a primary therapy or a tool to sensitise patients to treatment modalities such as chemotherapy and radiotherapy. We take a particular perspective towards miRNAs and their impact on rare cancers. Advancement in the delivery of miRNAs, from viral vectors and liposomal delivery to nanoparticle based, has led to a number of pre-clinical and clinical applications for microRNA cancer therapeutics. This is promising, especially in the setting of rare cancers.

MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression in a sequence-specific manner. Due to its association with an assortment of diseases, miRNAs have been extensively studied in the last decade. In this review, the current understanding of the role of miRNAs in the pathophysiology of adrenal tumors is discussed. The recent contributions of high-throughput miRNA profiling studies have identified miRNAs that have functional and molecular roles in adrenal tumorigenesis. With respect to the biological heterogeneity of adrenal tumors and the limitations of the current treatments, an improved understanding of miRNAs may hold potential diagnostic and therapeutic value to facilitate better clinical management., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Background: Bilateral recurrent laryngeal nerve (RLN) palsy following total thyroidectomy is a rare complication, however, poses significant morbidity to the patient when it does occur. The purpose of this paper was to determine the incidence of bilateral RLN palsy in a specialized thyroid unit and determine whether the routine use of intraoperative nerve monitoring (IONM) would alter the outcome., Methods: This is a retrospective review of prospectively gathered data. A total of 7406 patients underwent total thyroidectomy at the University of Sydney Endocrine Surgical Unit between January 1990 and February 2014. IONM was utilized on a selective basis and we sought to assess whether IONM would have altered outcome in those patients who developed bilateral RLN palsy., Results: Of the 7406 patients who underwent total thyroidectomy, seven patients (0.09%) developed bilateral RLN palsy during the study period. There was one permanent RLN palsy (0.01%) and routine IONM may have prevented one death and altered the outcome in two of the seven patients., Conclusion: Bilateral RLN palsy is a rare entity occurring in one out of 1000 cases in a specialized thyroid unit. IONM may facilitate the decision to pursue delayed surgery where the signal is lost on the first surgical side and has the potential to avoid bilateral RLN palsy following total thyroidectomy., (© 2015 Royal Australasian College of Surgeons.)

Extramedullary plasmacytoma (EMP) accounts for only 3% of plasma cell malignancies; others include multiple myeloma, plasma cell leukemia and solitary plasmacytoma of bone. The majority of EMPs are found in the upper respiratory tract. Other sites include the GI tract, bladder, CNS, thyroid, breast, testes, parotid gland, lymph nodes and skin. There are eight cases in the literature of adrenal plasmacytoma, however, only two were bilateral. We describe our recent experience of bilateral adrenal plasmacytoma and review of the literature. While EMP may present as aggressive locally destructive lesions, excellent local control can be achieved in a majority of cases. Follow-up should be lifelong due to risk of progression to multiple myeloma., Competing Interests: Financial & competing interests disclosure The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. No writing assistance was utilized in the production of this manuscript.

Background: Papillary thyroid cancer (PTC) frequently disseminates into cervical lymph nodes. Lateral node involvement is described in up to 50 % patients undergoing prophylactic lateral neck dissection. This study aimed to assess this finding and identify which factors predict for occult lateral node disease., Methods: Patients with fine needle aspiration-confirmed PTC (Bethesda V or VI), without evidence of cervical lymph node metastases, underwent a total thyroidectomy with prophylactic ipsilateral central and level 3 dissection. Level 3 nodes were removed by compartmental dissection or by sampling the sentinel nodes overlying the jugular vein, according to surgeon preference. Data were collected prospectively from January 2011 to August 2014. Statistical analysis was performed by SPSS software., Results: A total of 137 patients underwent total thyroidectomy with prophylactic ipsilateral central and level 3 dissection for PTC. The incidence of occult level 3 disease was 30 % (41/137 patients). A total of 48 % of patients (66/137) harbored occult central neck disease. A total of 80.5 % of patients with pN1b disease had macrometastases (≥2 mm), and 15 % exhibited skip metastases with central compartment sparing. In patients with pN1b disease, a median of 6 level 3 nodes were retrieved, with an average involved nodal ratio of 0.29. Multivariate regression demonstrated risk factors for occult lateral neck metastasis include tumor size (odds ratio 1.1), upper pole tumors (odds ratio 6.6), and vascular invasion (odds ratio 3.2) (p < 0.05)., Conclusions: PTC is associated with a significant incidence of occult central and lateral nodal metastases. In patients undergoing prophylactic central neck dissection, inclusion of level 3 dissection should be considered in patients with large upper lobe cancers.