Morbidity and Outcomes of Primary Tumor Management in Patients with Widely Metastatic Well-Differentiated Small Bowel Neuroendocrine Tumors.

BACKGROUND: The benefit of primary tumor resection in distant metastatic small bowel neuroendocrine tumors (SBNETs) is controversial, with treatment-based morbidity not well-defined. We aimed to determine the impact of primary tumor resection on development of disease-specific complications in patients with metastatic well-differentiated SBNETs. PATIENTS AND METHODS: A retrospective analysis was performed of patients diagnosed with metastatic well-differentiated jejunal/ileal SBNETs at a single tertiary care cancer center from 1980 to 2016. Outcomes were compared on the basis of treatment selected at diagnosis between patients who underwent initial medical treatment or primary tumor resection. RESULTS: Among 180 patients, 71 underwent medical management and 109 primary tumor resection. Median follow-up was 116 months. Median event-free survival did not differ between treatment approaches (log-rank p = 0.2). In patients medically managed first, 16/71 (23%) required surgery due to obstruction, perforation, or bleeding. These same complications led to resection at presentation in 31/109 (28%) surgically treated patients. Development of an obstruction from the primary tumor was not associated with disease progression/recurrence (HR 1.14, 95% CI 0.75-1.75) with all patients recovering postoperatively. Ongoing tumor progression requiring secondary laparotomy was associated with worse mortality (HR 7.51, 95% CI 3.3-16.9; p < 0.001) and occurred in 20/109 (18%) primary tumor resection and 7/16 (44%) initially medically treated patients. CONCLUSIONS: Rates of event-free survival among patients with metastatic SBNETs do not differ on the basis of primary tumor management. The development of an obstruction from the primary tumor was not associated with worse outcomes with all patients salvaged. Regardless of initial treatment selected, patients with metastatic SBNET should be closely followed for early signs of primary tumor complications.

Novel prognostic nomogram for predicting recurrence-free survival in medullary thyroid carcinoma.

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/.

FGFR2::TACC2 fusion as a novel KIT-independent mechanism of targeted therapy failure in a multidrug-resistant gastrointestinal stromal tumor.

Genetic alterations in FGF/FGFR pathway are infrequent in gastrointestinal stromal tumors (GIST), with rare cases of quadruple wildtype GISTs harboring FGFR1 gene fusions and mutations. Additionally, FGF/FGFR overexpression was shown to promote drug resistance to kinase inhibitors in GISTs. However, FGFR gene fusions have not been directly implicated as a mechanism of drug resistance in GISTs. Herein, we report a patient presenting with a primary small bowel spindle cell GIST and concurrent peritoneal and liver metastases displaying an imatinib-sensitive KIT exon 11 in-frame deletion. After an initial 9-month benefit to imatinib, the patient experienced intraabdominal peritoneal recurrence owing to secondary KIT exon 13 missense mutation and FGFR4 amplification. Despite several additional rounds of tyrosine kinase inhibitors (TKI), the patient's disease progressed after 2 years and presented with multiple peritoneal and liver metastases, including one pericolonic mass harboring secondary KIT exon 18 missense mutation, and a concurrent transverse colonic mass with a FGFR2::TACC2 fusion and AKT2 amplification. All tumors, including primary and recurrent masses, harbored an MGA c.7272 T > G (p.Y2424*) nonsense mutation and CDKN2A/CDKN2B/MTAP deletions. The transcolonic mass showed elevated mitotic count (18/10 HPF), as well as significant decrease in CD117 and DOG1 expression, in contrast to all the other resistant nodules that displayed diffuse and strong CD117 and DOG1 immunostaining. The FGFR2::TACC2 fusion resulted from a 742 kb intrachromosomal inversion at the chr10q26.3 locus, leading to a fusion between exons 1-17 of FGFR2 and exons 7-17 TACC2, which preserves the extracellular and protein tyrosine kinase domains of FGFR2. We present the first report of a multidrug-resistant GIST patient who developed an FGFR2 gene fusion as a secondary genetic event to the selective pressure of various TKIs. This case also highlights the heterogeneous escape mechanisms to targeted therapy across various tumor nodules, spanning from both KIT-dependent and KIT-independent off-target activation pathways.

Prophylactic Lateral Neck Dissection for Medullary Thyroid Carcinoma is not Associated with Improved Survival.

BACKGROUND: Patients with medullary thyroid carcinoma (MTC) often receive lateral lymph node dissection with total thyroidectomy when calcitonin levels are elevated, even in the absence of structural disease, but the effect of this intervention on disease-specific outcomes is not known. PATIENTS AND METHODS: We retrospectively reviewed patients from 1986 to 2017 who underwent thyroidectomy with curative intent for MTC at our institution. The association of disease-specific survival and clinicopathologic features was examined using univariate and multivariate Cox regression. RESULTS: We identified 316 patients who underwent curative resection for MTC. Overall and disease-specific survival were 76% and 86%, respectively, at 10 years. To investigate the effect of prophylactic ipsilateral lateral lymph node dissection, we analyzed 89 patients without known structural disease in the neck lymph nodes at the time of resection and preoperative calcitonin > 200 pg/ml, of whom 45 had an ipsilateral lateral lymph node dissection (LND) and 44 did not. There were no differences in tumor size or preoperative calcitonin levels. There was no difference at 10 years in cumulative incidence of recurrence in the neck (20.9% LND vs. 30.4% no LND, p = 0.46), cumulative incidence of distant recurrence (18.3% vs. 18.4%, p = 0.97), disease-specific survival (86% vs. 93%, p = 0.53), or overall survival (82% vs. 90%, p = 0.6). CONCLUSION: Lateral neck dissection in the absence of clinical or radiologic abnormal lymph nodes is not associated with improved survival in patients with MTC.

Grading of medullary thyroid carcinoma on the basis of tumor necrosis and high mitotic rate is an independent predictor of poor outcome.

Medullary thyroid carcinoma (MTC) is a rare nonfollicular cell-derived tumor. A robust grading system may help better stratify patients at risk for recurrence and death from disease. In total, 144 MTC between 1988 and 2018 were subjected to a detailed histopathologic evaluation. Clinical and pathologic data were correlated with disease specific survival (DSS), local recurrence free survival (LRFS)  and distant metastasis free survival (DMFS). Median age was 53 years (range: 3-88). Median tumor size was 1.8 cm (range: 0.2-11). Lymph node metastases were present in 84 (58%) cases while distant metastases at presentation were found in 9 (6%) patients. Seven (5%) had ≥5 mitoses/10 HPFs. Tumor necrosis was present in 30 cases (20%) while lymphovascular invasion occurred in 41 (28%) of tumors. Extra-thyroidal extension was found in 44 (31%) and positive margins were seen in 19 (14%). There was a strong correlation between increasing tumor size and tumor necrosis (p < 0.001). Median follow up was 39 months. In univariate analysis, male gender, higher American Joint Committee on Cancer (AJCC) stage group, larger tumor size, tumor necrosis, high mitotic index (≥5/10 HPF), nodal status, size of largest nodal metastasis, and elevated postoperative serum calcitonin predicted worse DSS, LRFS, and DMFS (p < 0.05). Extra-thyroidal extension correlated with DSS and DMFS while positive margins and distant metastasis at presentation imparted worse DSS (p < 0.05). In multivariate analysis, tumor necrosis and mitotic activity (5 mitosis/10 HPFs as the cutoff) were the only independent predictors for DSS (p = 0.008 and 0.026, respectively). Tumor necrosis was the sole independent prognostic factor for LRFS and DMFS (p = 0.001 and 0.003, respectively). The presence of tumor necrosis and high mitotic rate are powerful independent prognostic factors in MTC and outperform serum calcitonin and stage. We propose a grading system based on tumor necrosis and mitotic activity to better stratify MTC patients for counseling, post-resection surveillance, and therapy.

Predicting malignancy in patients with adrenal tumors using 18 F-FDG-PET/CT SUVmax.

BACKGROUND AND OBJECTIVES: 18 F-fluorodeoxyglucose positron emission tomography/computed tomography (18 F-FDG-PET/CT) parameters may help distinguish malignant from benign adrenal tumors, but few have been externally validated or determined based on definitive pathological confirmation. We determined and validated a threshold for 18 F-FDG-PET/CT maximum standard uptake value (SUVmax) in patients who underwent adrenalectomy for a nonfunctional tumor. METHODS: Database review identified patients with 18 F-FDG-PET/CT images available (training cohort), or only SUVmax values (validation cohort). Discriminative accuracy was assessed by area under the curve (AUC), and the optimal cutoff value estimated by maximally selected Wilcoxon rank statistics. RESULTS: Of identified patients (n = 171), 86 had adrenal metastases, 20 adrenal cortical carcinoma, and 27 adrenal cortical adenoma. In the training cohort (n = 96), SUVmax was significantly higher in malignant versus benign tumors (median 8.3 vs. 3.0, p < .001), with an AUC of 0.857. Tumor size did not differ. The optimal cutoff SUVmax was 4.6 (p < .01). In the validation cohort (n = 75), this cutoff had a sensitivity of 75% and specificity 55%. CONCLUSIONS: 18 F-FDG-PET/CT SUVmax was associated with malignancy. Validation indicated that SUVmax ≥ 4.6 was suggestive of malignancy, while lower values did not reliably predict benign tumor.

Adrenal Metastasectomy in the Presence and Absence of Extraadrenal Metastatic Disease.

OBJECTIVE: To determine if there are differences in overall survival (OS) or event-free survival (EFS) in patients with and without concomitant extra-adrenal metastases undergoing adrenal metastasectomy. BACKGROUND: There is growing interest in the use of local therapies in patients with oligometastatic disease. Previously published series have indicated that long-term survival is possible with resection. Adrenalectomy has been used to treat adrenal metastases in select patients. METHODS: Patients who underwent adrenal metastasectomy from 1994 to 2015 were identified from a prospectively maintained institutional database of adrenalectomy patients, excluding adrenalectomies due to tumor extension or for palliation. Sites of disease, treatment history, and survival data were extracted from chart review. RESULTS: One hundred seventy-four patients were included. Tumor histology included 68 nonsmall cell lung cancer, 34 renal cancer, 18 colorectal cancer, 11 melanoma cancer, 10 hepatocellular cancer, 8 sarcoma cancer, and 25 other cancers. The median follow-up among survivors was 5.2 (1-21) years. OS at 3 and 5 years was 50% and 40%, respectively. Patients with (n = 83) and without (n = 91) extra-adrenal metastases did not differ with respect to age, adrenal tumor size, or margin status. Median OS (3.3 years for patients with concomitant extra-adrenal metastases and 3.0 years for patients with isolated adrenal metastases; P = 0.816) and EFS (9.39 vs 9.59 months; P = 0.87) were similar. Factors negatively associated with OS included adrenal tumor size (P < 0.01), renal primary versus other (P < 0.01), and adrenal margin status (P < 0.01). CONCLUSIONS: In selected patients undergoing adrenal metastasectomy, there were no significant differences in OS or EFS between patients with and without concomitant extra-adrenal metastases.

Long-Term Oncologic Outcomes After Curative Resection of Familial Medullary Thyroid Carcinoma.

INTRODUCTION: Long-term outcomes after curative resection in patients with germline RET mutations and medullary thyroid cancer (MTC) are highly variable and mutation-specific oncologic outcomes are not well-described. METHODS: Sixty-six patients identified from 1986 to 2017 from a single-institution cancer database were assessed for recurrence and survival using Kaplan-Meier estimates, and correlated with clinicopathologic features using log-rank or Cox proportional hazards. RESULTS: Median follow-up was 9.3 years (range 0.3-31.5), median tumor diameter was 1.5 cm (range 0.1-7.5), and preoperative calcitonin was known in 41 patients [median 636 (range 0-9600)]. Overall survival (OS) of the cohort was 94% at 10 years, the cumulative incidence of locoregional recurrence was 38% at 10 years, and 19/24 (79%) patients underwent repeat neck operation. The cumulative incidence of distant recurrence was 27% at 10 years. Predictors of distant recurrence were tumor size, positive lymph nodes, and pre- and postoperative carcinoembryonic antigen, but not calcitonin. M918T mutation-bearing patients had 10-year distant recurrence-free survival of 0%, compared with 83% in all other patients (p < 0.001), and equivalent 10-year OS (100% vs. 92%; p = 0.49). CONCLUSIONS: Structural and metastatic recurrence is common in patients with germline RET mutations, and MTC and can occur 20 years after initial treatment, however survival remains high. Management should focus on optimal surveillance strategies and long-term control of structural disease.

Complete Responses to Mitotane in Metastatic Adrenocortical Carcinoma-A New Look at an Old Drug.

PURPOSE: Based largely on reports that predate modern reporting standards, mitotane has been considered a systemic treatment option for both hormone control and antitumor control of metastatic adrenocortical cancer (ACC), although the therapeutic window is narrow. METHODS: We searched electronic medical records to identify patients with metastatic ACC treated and prescribed single-agent mitotane at Memorial Sloan Kettering Cancer Center from March 15, 1989-September 18, 2015. Reference radiologists reviewed all imaging and determined efficacy according to Response Evaluation Criteria in Solid Tumors 1.1. Patient demographics, toxicities, and treatment outcomes were reviewed. Next-generation sequencing was performed in selected cases. RESULTS: Thirty-six patients were identified. The mean age was 54 and 50% had functional tumors. Grade 3 or greater toxicities were documented in 16 out of 36 patients (44%) and 17% had documented long term adrenal insufficiency. Progression of the disease as the best response occurred in 30 out of 36 patients (83%) and one patient (3%) experienced clinical progression. Three patients achieved a complete response (CR) (8%), one patient achieved a partial response (3%), and one patient (3%) had stable disease after slow disease progression prior to initiation of therapy (durable for 6 months). All responders had nonfunctional tumors. Next-generation sequencing in two of the three CR patients was performed and failed to identify any novel alterations. CONCLUSION: In this retrospective series, mitotane had a low response rate and low tumor control rate; however, a disproportionately high complete response rate suggested it should be used in selected individuals. Adrenal insufficiency is common with mitotane use and aggressive treatment with steroid supplementation should be considered when appropriate to avoid excess toxicities. Biomarkers are desperately needed to further define this disease. IMPLICATIONS FOR PRACTICE: This is the first objective report of single-agent mitotane using modern objective criteria. Although the vast majority of patients did not respond (and toxicity was high), we identified a remarkable 8% complete response rate (i.e. cure) in biopsy proven stage IV adrenocortical cancer patients. Biomarkers are desperately needed for this rare disease.

Observation versus Resection for Small Asymptomatic Pancreatic Neuroendocrine Tumors: A Matched Case-Control Study.

OBJECTIVE: To analyze the natural history of small asymptomatic pancreatic neuroendocrine tumors (PanNET) and to present a matched comparison between groups who underwent either initial observation or resection. Management approach for small PanNET is uncertain. METHODS: Incidentally discovered, sporadic, small (<3 cm), stage I-II PanNET were analyzed retrospectively between 1993 and 2013. Diagnosis was determined either by pathology or imaging characteristics. Intention-to-treat analysis was applied. RESULTS: A total of 464 patients were reviewed. Observation was recommended for 104 patients (observation group), and these patients were matched to 77 patients in the resection group based on tumor size at initial imaging. The observation group was significantly older (median 63 vs. 59 years, p = 0.04) and tended towards shorter follow-up (44 vs. 57 months, p = 0.06). Within the observation group, 26 of the 104 patients (25 %) underwent subsequent tumor resection after a median observation interval of 30 months (range 7-135). At the time of last follow-up of the observation group, the median tumor size had not changed (1.2 cm, p = 0.7), and no patient had developed evidence of metastases. Within the resection group, low-grade (G1) pathology was recorded in 72 (95 %) tumors and 5 (6 %) developed a recurrence, which occurred after a median of 5.1 (range 2.9-8.1) years. No patient in either group died from disease. Death from other causes occurred in 11 of 181 (6 %) patients. CONCLUSIONS: In this study, no patient who was initially observed developed metastases or died from disease after a median follow-up of 44 months. Observation for stable, small, incidentally discovered PanNET is reasonable in selected patients.

Complete metastasectomy for renal cell carcinoma: Comparison of five solid organ sites.

BACKGROUND AND OBJECTIVES: Patients with metastatic RCC can undergo metastasectomy to improve survival time. Our goal was to provide and compare characteristics and oncological outcomes of RCC patients who underwent complete metastasectomy at a single organ site. METHODS: A total of 138 RCC patients were identified as undergoing complete metastasectomy at a single organ site including adrenal, lung, liver, pancreas, or thyroid. Competing risk regression analysis was used to assess RFS and CSS adjusting for several covariates. RESULTS: In this highly selected cohort, RFS and CSS was 27% and 84% at 5 years following metastasectomy, respectively. Univariate analysis revealed that removal of multiple tumors, younger age, and a shorter interval between nephrectomy and metastasis was associated with worse RFS. Larger tumors and sarcomatoid histology at nephrectomy was associated with worse CSS. We found no evidence that metastases at the time of RCC diagnosis influenced recurrence or survival. Tumor size, number of metastases resected, and time from nephrectomy to first recurrence was significantly different, but recurrence rates were not found to be significantly different, when compared across all organ sites. CONCLUSIONS: These findings inform clinical and surgical management of select RCC patients with isolated metastasis to one of several organ sites. J. Surg. Oncol. 2016;114:375-379. © 2016 Wiley Periodicals, Inc.

Oncologic outcomes after completion thyroidectomy for patients with well-differentiated thyroid carcinoma.

BACKGROUND: At our institution, thyroid lobectomy is employed as a definitive operation for unifocal intrathyroidal low risk cancers and thus completion thyroidectomy is rarely performed. The purpose of this study was to identify the indications for selective completion thyroidectomy and to report oncologic outcomes. METHODS: A retrospective review was performed to identify patients who underwent planned completion thyroidectomy for well-differentiated thyroid carcinoma (WDTC) from 2001 to 2010 based on initial lobectomy pathology. Assessment for risk of recurrence was based on the American Thyroid Association Initial Risk Stratification. RESULTS: During the 10-year study period, 79 patients underwent completion thyroidectomy for WDTC. Forty-four (56 %) patients were low risk and 35 (44 %) were intermediate risk. Completion thyroidectomy was recommended for 64 patients, whereas 15 patients were given an option of surveillance but ultimately decided to have surgery. Patients in the "recommended group" had more T3 tumors and fewer T1a tumors (p = 0.005 and 0.006, respectively). These patients also were more likely to be intermediate risk (p = 0.008) and to present with aggressive histology (p = 0.002). The rate of contralateral tumors (n = 27) was similar between both groups (35 and 33 %, respectively). Contralateral cancers were micropapillary in 24 of 27 (89 %) patients, 10 (40 %) of whom had multifocal disease. There were two pulmonary recurrences and no local-regional recurrences (median follow-up of 42.3 months). CONCLUSIONS: Completion thyroidectomy is infrequent and performed for a select group of intermediate and low risk WDTCs at our institution with low recurrence rates. Incidental multifocal and unifocal contralateral cancers are common after completion thyroidectomy.

Pancreatic metastasectomy: the Memorial Sloan-Kettering experience and a review of the literature.

Isolated pancreatic metastases may occur in patients with many types of cancer. Several retrospective case series have been published demonstrating the feasibility of resection in selected patients. Here we report our experience with pancreatic metastasectomy in 70 patients and review the published literature. Our findings suggest that long-term survival is associated with resection in selected patients but these outcomes must be weighed against the significant morbidity that is associated with pancreatic resection.

Imaging and management of a small cell lung cancer metastasis/adrenal adenoma collision tumor: a case report and review of the literature.

OBJECTIVE: We report a case of an adrenal collision tumor composed of a small cell lung carcinoma metastasis and a benign adrenal adenoma identified preoperatively on FDG-PET, CT and MRI and confirmed pathologically. METHODS: The patient's history, preoperative imaging characteristics, postoperative course, and histopathology are described. A review of the literature addressing adrenal collision tumors is provided. RESULTS: A 47-year-old female was found to have a left upper lobe lung mass and an adrenal lesion on imaging. FDG-PET, CT and MRI of the adrenal suggested a metastatic lesion adjacent to an adrenal adenoma. CT-guided biopsy of the adrenal gland was consistent with a small cell lung cancer metastasis. The patient underwent systemic chemotherapy and had complete resolution of the left upper lobe mass. Post-treatment FDG-PET demonstrated a persistently enlarged adrenal gland with decreased but persistent FDG uptake. The patient underwent adrenalectomy and pathologic examination demonstrated a small cell lung cancer/adenoma collision tumor. CONCLUSIONS: This case and a review of the literature demonstrate that FDG, CT and MR imaging can all characterize the separate components of collision tumors within the adrenal gland.

RBM10 loss induces aberrant splicing of cytoskeletal and extracellular matrix mRNAs and promotes metastatic fitness.

RBM10 modulates transcriptome-wide cassette exon splicing. Loss-of-function RBM10 mutations are enriched in thyroid cancers with distant metastases. Analysis of transcriptomes and genes mis-spliced by RBM10 loss showed pro-migratory and RHO/RAC signaling signatures. RBM10 loss increases cell velocity. Cytoskeletal and ECM transcripts subject to exon-inclusion events included vinculin (VCL), tenascin C (TNC) and CD44. Knockdown of the VCL exon inclusion transcript in RBM10-null cells reduced cell velocity, whereas knockdown of TNC and CD44 exon-inclusion isoforms reduced invasiveness. RAC1-GTP levels were increased in RBM10-null cells. Mouse Hras G12V /Rbm1O KO thyrocytes develop metastases that are reversed by RBM10 or by combined knockdown of VCL, CD44 and TNC inclusion isoforms. Thus, RBM10 loss generates exon inclusions in transcripts regulating ECM-cytoskeletal interactions, leading to RAC1 activation and metastatic competency. Moreover, a CRISPR-Cas9 screen for synthetic lethality with RBM10 loss identified NFkB effectors as central to viability, providing a therapeutic target for these lethal thyroid cancers.

RAS-Mutated Cytologically Indeterminate Thyroid Nodules: Prevalence of Malignancy and Behavior Under Active Surveillance.

Background: Genomic profiling is now available for risk stratification of cytologically indeterminate thyroid nodules (ITNs). Mutations in RAS genes (HRAS, NRAS, KRAS) are found in both benign and malignant thyroid nodules, although isolated RAS mutations are rarely associated with aggressive tumors. Because the long-term behavior of RAS-mutant ITNs is not well understood, most undergo immediate surgery. In this multicenter retrospective cohort study, we characterize tumor growth kinetics of RAS-mutant ITNs followed with active surveillance (AS) using serial ultrasound (US) scans and examine the histopathologic diagnoses of those surgically resected. Methods: US and histopathologic data were analyzed retrospectively from two cohorts: (1) RAS-mutant ITNs managed with AS at three institutions (2010-2023) and (2) RAS-mutant ITNs managed with immediate surgery at two institutions (2016-2020). AS cohort subjects had ≥3 months of follow-up and two or more US scans. Cumulative incidence of nodule growth was determined by the Kaplan-Meier method and growth by ≥72% change in tumor volume. Pathological diagnoses for the immediate surgery cohort were analyzed separately. Results: Sixty-two patients with 63 RAS-mutated ITNs under AS had a median diameter of 1.7 cm (interquartile range [IQR] 1.2-2.6) at time of diagnosis. During a median AS period of 23 months (IQR 9.5-53.5 months), growth was observed in 12 of 63 nodules (19.0%), with a cumulative incidence of 1.9% (1 year), 23.0% (3 years), and 28.0% (5 years). Most nodules (81.0%) demonstrated stability. Surgery was ultimately performed in 6 nodules, of which 1 (16.7%) was malignant. In the cohort of 209 RAS-mutant ITNs triaged to immediate surgery, 33% were malignant (23.9% American Thyroid Association [ATA] low-risk cancers, 7.2% ATA intermediate-risk, and 1.9% ATA high-risk. During a median follow-up of 6.9 (IQR 4.4-7.1) years, there were no disease-specific deaths in these patients. Conclusions: We describe the behavior of RAS-mutant ITNs under AS and find that most demonstrate stability over time. Of the resected RAS-mutant nodules, most were benign; of the cancers, most were ATA low-risk. Immediate surgical resection of all RAS-mutant ITNs appears to be a low-value practice. Further research is needed to help define cases most appropriate for AS or immediate surgery.

Tumor proximity to the recurrent laryngeal nerve in patients with primary hyperparathyroidism undergoing parathyroidectomy.

BACKGROUND: Recurrent laryngeal nerve (RLN) injury is a rare complication for patients undergoing neck exploration for primary hyperparathyroidism (pHPT). Distances between RLNs and parathyroid adenomas have not been previously published. In this study we used a RLN monitor to identify the RLN and to measure the proximity to parathyroid tumors. METHODS: Patients with pHPT (n = 136) underwent neck exploration and had the clinical data recorded prospectively. Adenomas were recorded in 1 of 4 locations (right upper, right lower, left upper, left lower). Measurement of RLN to adenoma distances were recorded intraoperatively with the gland in situ. The RLN location was confirmed with a RLN monitor. RESULTS: The average RLN to adenoma distance was 0.52 ± 0.52 cm. Adenomas in the right upper position were significantly closer to the nerve (0.25 ± 0.39 cm) compared with adenomas in the left upper (0.48 ± 0.61 cm, p = .03), left lower (0.70 ± 0.53 cm, p < .001), and right lower position (1.02 ± 0.56 cm, p < .001). Left upper adenomas were also significantly closer to the nerve compared with right lower adenomas (p < .001). Adenomas in the right upper position abutted the nerve more often (47 %) compared with adenomas in other positions (p = .001). There were no perioperative characteristics that predicted tumor abutment. There were no permanent RLN injuries. CONCLUSION: In patients with sporadic pHPT, parathyroid adenomas in the right upper location have, on average, greater proximity to the RLN and are more often directly abutting compared with adenomas in other locations.

Primary Mesenchymal Tumors of the Thyroid Gland: A Modern Retrospective Cohort Including the First Case of TFE3-Translocated Malignant Perivascular Epithelioid Cell Tumor (PEComa).

Primary mesenchymal tumors of the thyroid gland are extremely rare, with only case reports and small case series documented in the English literature, many of which were published prior to the era of molecular pathology. In the current study, we aim to present a contemporary multi-centric cohort of thyroid mesenchymal tumors. Nineteen primary thyroid mesenchymal tumors were collected from three tertiary centers. Their clinicopathologic features, immunoprofile, molecular alterations, and outcome were described. Eight cases were classified as benign or intermediate with solitary fibrous tumor being the most common histotype (n = 3). The remaining 11 cases were malignant, including three angiosarcomas, one epithelioid hemangioendothelioma, one adamantinoma-like Ewing sarcoma, one biphasic synovial sarcoma, one malignant melanocytic peripheral nerve sheath tumor (melanotic schwannoma), one myxofibrosarcoma, and two undifferentiated pleomorphic/spindle sarcomas (one of which was radiation-induced). Six tumors showed characteristic diagnostic translocations. We herein also described the first case of thyroid malignant perivascular epithelioid cell tumor (PEComa) with RBM10-TFE3 fusion in a 35-year-old female patient. Thyroid mesenchymal tumors, benign or malignant, are rare with a broad spectrum of possible diagnoses. A comprehensive examination to include histology, immunohistochemistry, and molecular testing is essential for the correct diagnosis and to distinguish them from anaplastic thyroid carcinoma. PEComa may occur as a primary tumor of the thyroid gland, expanding the histologic spectrum of thyroid mesenchymal tumors.

Tumor Grade Predicts for Calcitonin Doubling Times and Disease-Specific Outcomes After Resection of Medullary Thyroid Carcinoma.

Background: Tumor grade is a new validated prognostic factor for medullary thyroid cancer (MTC). Calcitonin doubling time can predict MTC recurrence. We aimed to describe the association of tumor grade with calcitonin doubling and its effect on disease-specific outcomes times after resection. Methods: A retrospective analysis of MTC patients who underwent resection at a single tertiary-care cancer center between 1986 and 2017 were evaluated. Tumors were designated as high-grade MTC if two head and neck pathologists identified mitotic index ≥5 per 2 mm2, tumor necrosis, or a Ki67 proliferative index ≥5% within the tumor. Calcitonin doubling time was calculated using a validated calculator with at least three consecutive levels. Using Cox proportional hazards models, outcomes evaluated included locoregional relapse-free survival (LRFS), distant metastasis-free survival (DMFS), and overall survival (OS). Results: Among 117 patients, 95 were low grade and 22 high grade. Median follow-up was 70.2 months. High-grade patients demonstrated significantly faster calcitonin doubling times when compared with low-grade patients (8.51 ± 3.22 months vs. 38.42 ± 11.19 months; p < 0.001). In addition, most high-grade patients (66.7%) had calcitonin doubling times less than 1 year compared with fewer low-grade patients (1.0%; p < 0.001). High- and low-grade patients were further stratified by those who had calcitonin doubling times less than or greater than 2 years-a previously validated prognostic cutoff point. For patients with calcitonin doubling times less than 2 years, 70% were high grade, while 30% were low grade (p < 0.001). On multivariate analysis comparing grade and calcitonin doubling times, high-grade patients had significantly worse LRFS (hazards ratio [HR] 4.77 [confidence interval; CI 1.19-8.81]), DMFS (HR 7.25 [CI 2.36-22.28]), and OS (HR 6.04 [CI 1.85-19.72]; p < 0.05 for all), while calcitonin doubling times less than 2 years had worse DMFS (HR 7.22 [CI 1.05-49.75]). High-grade patients with calcitonin doubling times less than 2 years had associated worse LRFS and OS (both p < 0.05) compared with low-grade patients. Conclusions: The majority of high-grade MTC patients have calcitonin doubling times less than 2years. Close monitoring should be advocated for patients assessed to have high-grade tumors as they are at risk for poor disease-specific outcomes and structural recurrence.