Management of radioiodine refractory differentiated thyroid cancer: the Latin American perspective.

Radioiodine (RAI) refractory differentiated thyroid cancer is an uncommon and challenging situation that requires a multidisciplinary approach to therapeutic strategies. The definition of RAI-refractoriness is usually a clear situation in specialized centers. However, the right moment for initiation of multikinase inhibitors (MKI), the time and availability for genomic testing, and the possibility of prescribing MKI and selective kinase inhibitors differ worldwide.Latin America (LA) refers to the territories of the world that stretch across two regions: North America (including Central America and the Caribbean) and South America, containing 8.5% of the world's population. In this manuscript, we critically review the current standard approach recommended for patients with RAI refractory differentiated thyroid cancer, emphasizing the challenges faced in LA. To achieve this objective, the Latin American Thyroid Society (LATS) convened a panel of experts from Brazil, Argentina, Chile, and Colombia. Access to MKI compounds continues to be a challenge in all LA countries. This is true not only for MKI but also for the new selective tyrosine kinase inhibitor, which will also require genomic testing, that is not widely available. Thus, as precision medicine advances, significant disparities will be made more evident, and despite efforts to improve coverage and reimbursement, molecular-based precision medicine remains inaccessible to most of the LA population. Efforts should be undertaken to alleviate the discrepancies between the current state-of-the-art care for RAI-refractory differentiated thyroid cancer and the present situation in Latin America.

Papillary Thyroid Microcarcinoma: Insights from a Cohort of 257 Thyroidectomized Patients.

Papillary thyroid microcarcinoma management evolved, and less aggressive strategies are now considered. Questions, however, remain on these tumors' behavior, particularly on developing countries' real ground healthcare scenarios. Our aim is to gather insights on the natural history of papillary thyroid microcarcinoma on patients treated with thyroidectomy in Brazil. Consecutive patients diagnosed with papillary thyroid microcarcinoma had their clinical characteristics, interventions, and outcomes described. Patients were classified as incidental or nonincidental based on the diagnosis after or before surgery, respectively. A sum of 257 patients were included, 84.0% of which were women, and the mean age was of 48.3±13.5 years. The mean tumor size was of 0.68±0.26 cm, 30.4% were multifocal, 24.5% had cervical metastasis, and 0.4% distant metastasis. The nonincidental and incidental tumors differed in tumor size (0.72±0.24 and 0.60±0.28 cm, respectively, p=0.003) and in presence of cervical metastasis (31.3% and 11.9%, respectively, p<0.001). Male sex, nonincidental diagnosis, and younger age were independent predictors of cervical metastasis. After 5.5 years (P25-75 2.5-9.7) of follow-up, only 3.8% of patients had persistent structural disease (3.4% cervical). Predictors of persistent disease at multivariate analysis included cervical metastasis and multicentricity. In conclusion, incidental and nonincidental papillary thyroid microcarcinoma patients of the population studied displayed excellent outcomes. Cervical metastasis and multicentricity were frequent findings and prognostic factors for persistent disease.

BRAF mutations in thyroid cancer.

PURPOSE OF REVIEW: Activating mutations in the mitogen-activated protein kinase (MAPK) pathway play an important role in papillary (PTC) and anaplastic (ATC) thyroid cancer. The aim of this review is to discuss the impact of BRAF mutations on clinical features and treatment of patients with thyroid cancer. RECENT FINDINGS: Despite the unfavorable course associated with PTCs harboring BRAF V600E mutation, its prognostic role remains debated. BRAF V600E-driven tumors exhibit high Extracellular signal-regulated kinase phosphorylation, leading to unregulated cell proliferation and inhibition of the required genes for radioiodine responsiveness in thyroid cancer. The mechanism associated with the variable BRAF-mutant tumor aggressiveness remains unclear and other pathways are likely to co-operate to promote cancer progression. Overexpression of the Notch signaling and loss of individual switch/ sucrose non-fermentable chromatin-remodeling complexes subunits might be involved. The combination of the BRAF inhibitor dabrafenib and the mitogen-activated protein kinase kinase inhibitor trametinib has shown remarkable results in clinical trials of patients with BRAF-mutated ATCs. SUMMARY: The impact of BRAF mutations on the clinical outcomes of PTC remains debatable. In ATCs, in turn, BRAF mutations identify patients eligible for targeted therapy, which is now considered in two settings: as neoadjuvant for unresectable tumors and as a treatment for metastatic or unresectable disease.

Reappraising the Diagnostic Accuracy of Post-Treatment Whole-Body Scans for Differentiated Thyroid Carcinoma.

Initial treatment for differentiated thyroid carcinoma (DTC) often consists of surgery and the administration of radioiodine. In this context, post-treatment Whole-Body Scans (ptWBS) are currently recommended, but data on its diagnostic accuracy are rare. The aim of the study was to evaluate the performance of ptWBS for distant metastasis in DTC patients. We included DTC patients who received radioiodine and underwent ptWBS between 2009-2015. The medical data were independently reviewed by two specialists to evaluate the concordance of positive distant ptWBS uptake and distant metastasis documented by imaging exams (gold standard). We studied 268 DTC patients. The mean age was 46±16 years (82% women), and papillary thyroid carcinoma was diagnosed in 87% of the patients. The median tumor size was 2.7 cm, 40% had lymph node involvement, and 11% had distant metastasis. Twenty-eight patients (10%) had distant ptWBS uptake, and nine of them (32%) were false-positives. In addition, nine false-negative ptWBS uptakes were identified. The overall performance of ptWBS showed 68% sensitivity and 96% specificity with significantly different performance according to the American Thyroid Association (ATA) risk groups. While the ptWBS performance for ATA low-intermediate-risk showed 29% sensitivity, 97% specificity, and Kappa of 0.19, the ATA high-risk group ptWBS displayed high sensitivity (82%), specificity (100%), and good agreement (Kappa 0.74). ptWBS is useful for a subgroup of ATA high-risk DTC patients. The overall poor performance of ptWBS suggests that it should be reconsidered for routine use in ATA at low to intermediate risk: the exam has little value to this subgroup.

Global DNA methylation profile in medullary thyroid cancer patients.

BACKGROUND: Changes in global DNA methylation have been suggested to cause genomic instability leading to increased risk of cancer. The accumulation of epigenetic changes is believed to contribute to tumorigenesis and dedifferentiation, but the effects of such changes in thyroid cancer are still yet defined. OBJECTIVE: To evaluate the global DNA methylation levels in thyroid cancer patients. METHODS: Total DNA was extracted from peripheral blood leukocytes of the medullary thyroid carcinoma (MTC) and papillary thyroid carcinoma (PTC) patients and the methylation pattern was evaluated using the Imprint Methylated DNA Quantification kit (Sigma-Aldrich). RESULTS: A total of 42 patients were analyzed (24 MTC, 12 PTC, and 6 controls). For MTC, the mean age was 41 ±â€¯20 years, 54% were women and 12 cases were sporadic. The median calcitonin level at diagnosis was 1692 (637-8865), 65% of the MTC patients had local metastases and 23% distant metastases. For PTC, the median age was 43 ±â€¯15 years, 58% were women and 50% had local metastases. The percentage of overall methylation differed according to the tumor subtype. Patients with MTC had a higher level of DNA methylation when compared to individuals with PTC (35 (24-48) vs. 17 (6.5-20.5); P = 0.002, respectively). Interestingly, among patients with MTC, individuals with the sporadic form of the disease had a higher level of methylation when compared to the hereditary form (25 (16-37) vs. 43 (33-52); P = 0.025, respectively). No association was observed between global methylation levels and clinical and/or oncological characteristics of the disease. CONCLUSION: Global methylation levels were higher in MTC as compared to PTC patients. These results suggest the overall DNA methylation profile may be influenced by the histological subtype of thyroid cancer.

Advances and controversies in the management of medullary thyroid carcinoma.

PURPOSE OF REVIEW: Medullary thyroid carcinoma (MTC) comprises approximately 4% of all malignant thyroid neoplasms. Although the majority of patients have a good prognosis, a subgroup of patients develops progressive disease and requires systemic therapy. Here, we focused on the current MTC therapeutic approaches and discussed the advantages and disadvantages of molecular targeted therapies. RECENT FINDINGS: Targeted molecular therapies that inhibit RET and other tyrosine kinase receptors involved in angiogenesis have been shown to improve progression-free survival in patients with advanced MTC. Two drugs, vandetanib and cabozantinib, have been approved for the treatment of progressive or symptomatic MTC, and several others have exhibited variable efficacy. No tyrosine kinase inhibitor has been shown to improve survival. Although no definitive recommendation can currently be made, cumulative data indicate that knowledge of the tumor mutational profile may facilitate improvements in targeted therapy for MTC. SUMMARY: Tyrosine kinase inhibitors are effective therapeutic agents for the treatment of progressive MTC. Nevertheless, it is not clear who will benefit the most from therapy, and the decision regarding when and how to initiate the treatment should be made based on the patient's medical history and tumor behavior. Hopefully, in the near future, molecular profiling of MTC can be used to determine the most effective molecular therapeutic target.

Outcomes of adrenal-sparing surgery or total adrenalectomy in phaeochromocytoma associated with multiple endocrine neoplasia type 2: an international retrospective population-based study.

BACKGROUND: The prevention of medullary thyroid cancer in patients with multiple endocrine neoplasia type 2 syndrome has demonstrated the ability of molecular diagnosis and prophylactic surgery to improve patient outcomes. However, the other major neoplasia associated with multiple endocrine neoplasia type 2, phaeochromocytoma, is not as well characterised in terms of occurrence and treatment outcomes. In this study, we aimed to systematically characterise the outcomes of management of phaeochromocytoma associated with multiple endocrine neoplasia type 2. METHODS: This multinational observational retrospective population-based study compiled data on patients with multiple endocrine neoplasia type 2 from 30 academic medical centres across Europe, the Americas, and Asia. Patients were included if they were carriers of germline pathogenic mutations of the RET gene, or were first-degree relatives with histologically proven medullary thyroid cancer and phaeochromocytoma. We gathered clinical information about patients'RET genotype, type of treatment for phaeochromocytoma (ie, unilateral or bilateral operations as adrenalectomy or adrenal-sparing surgery, and as open or endoscopic operations), and postoperative outcomes (adrenal function, malignancy, and death). The type of surgery was decided by each investigator and the timing of surgery was patient driven. The primary aim of our analysis was to compare disease-free survival after either adrenal-sparing surgery or adrenalectomy. FINDINGS: 1210 patients with multiple endocrine neoplasia type 2 were included in our database, 563 of whom had phaeochromocytoma. Treatment was adrenalectomy in 438 (79%) of 552 operated patients, and adrenal-sparing surgery in 114 (21%). Phaeochromocytoma recurrence occurred in four (3%) of 153 of the operated glands after adrenal-sparing surgery after 6-13 years, compared with 11 (2%) of 717 glands operated by adrenalectomy (p=0.57). Postoperative adrenal insufficiency or steroid dependency developed in 292 (86%) of 339 patients with bilateral phaeochromocytoma who underwent surgery. However, 47 (57%) of 82 patients with bilateral phaeochromocytoma who underwent adrenal-sparing surgery did not become steroid dependent. INTERPRETATION: The treatment of multiple endocrine neoplasia type 2-related phaeochromocytoma continues to rely on adrenalectomies with their associated Addisonian-like complications and consequent lifelong dependency on steroids. Adrenal-sparing surgery, a highly successful treatment option in experienced centres, should be the surgical approach of choice to reduce these complications.

AdE-1, a new inotropic Na(+) channel toxin from Aiptasia diaphana, is similar to, yet distinct from, known anemone Na(+) channel toxins.

Heart failure is one of the most prevalent causes of death in the western world. Sea anemone contains a myriad of short peptide neurotoxins affecting many pharmacological targets, several of which possess cardiotonic activity. In the present study we describe the isolation and characterization of AdE-1 (ion channel modifier), a novel cardiotonic peptide from the sea anemone Aiptasia diaphana, which differs from other cnidarian toxins. Although AdE-1 has the same cysteine residue arrangement as sea anemone type 1 and 2 Na(+) channel toxins, its sequence contains many substitutions in conserved and essential sites and its overall homology to other toxins identified to date is low (<36%). Physiologically, AdE-1 increases the amplitude of cardiomyocyte contraction and slows the late phase of the twitch relaxation velocity with no induction of spontaneous twitching. It increases action potential duration of cardiomyocytes with no effect on its threshold and on the cell's resting potential. Similar to other sea anemone Na(+) channel toxins such as Av2 (Anemonia viridis toxin II), AdE-1 markedly inhibits Na(+) current inactivation with no significant effect on current activation, suggesting a similar mechanism of action. However, its effects on twitch relaxation velocity, action potential amplitude and on the time to peak suggest that this novel toxin affects cardiomyocyte function via a more complex mechanism. Additionally, Av2's characteristic delayed and early after-depolarizations were not observed. Despite its structural differences, AdE-1 physiologic effectiveness is comparable with Av2 with a similar ED(50) value to blowfly larvae. This finding raises questions regarding the extent of the universality of structure-function in sea anemone Na(+) channel toxins.

Role of VEGF-A and its receptors in sporadic and MEN2-associated pheochromocytoma.

Pheochromocytoma (PHEO), a rare catecholamine producing tumor arising from the chromaffin cells, may occurs sporadically (76%-80%) or as part of inherited syndromes (20%-24%). Angiogenesis is a fundamental step in tumor proliferation and vascular endothelial growth factor (VEGF-A) is the most well-characterized angiogenic factor. The role of angiogenic markers in PHEO is not fully understood; investigations were therefore made to evaluate the expression of VEGF-A and its receptors in PHEO and correlate to clinical parameters. Twenty-nine samples of PHEO were evaluated for VEGF-A, VEGF receptor-1 (VEGFR-1) VEGFR-2 expression and microvessel density (MVD) by immunohistochemistry. Clinical data were reviewed in medical records. The mean age of patients was 38±14 years, and 69% were woman. VEGF-A, VEGFR-1 and VEGFR-2 staining were detected in nearly all PHEO samples. No significant correlation was observed between VEGF-A, VEGFR-1, VEGFR-2 expression or MVD and age at diagnosis, tumor size or sporadic and hereditary PHEO. However, the levels of expression of these molecules were significantly higher in malignant PHEO samples (p=0.027, p=0.003 and p=0.026, respectively).VEGF-A and its receptors were shown to be up-regulated in malignant PHEO, suggesting that these molecules might be considered as therapeutic targets for unresectable or metastatic tumors.

Distinct transcriptional and prognostic impacts of TERT promoter mutations C228T and C250T in papillary thyroid carcinoma.

TERT promoter mutations C228T and C250T are associated with disease aggressiveness and poor clinical outcomes in patients with papillary thyroid carcinomas. However, very little is known about the transcriptional consequences of these mutations and whether they both carry similar oncogenic potential. Here we characterized the transcriptional disturbances and clinical outcomes associated with the presence of each of these two mutations using data derived from The Cancer Genome Atlas. We observed that tumors harboring the C228T mutation (n=27) exhibited a 16-fold increase in TERT mRNA levels (P=5.3x10-42), whereas C250T tumors (n=8) showed only a 2-fold increase in expression (P=0.034). The C228T mutation was associated with the activation of signaling pathways controlling the cell cycle, cellular division, and extracellular matrix degradation. Univariate analysis demonstrated that the C228T mutation was associated with older age at diagnosis, large tumor size, lymph node invasion, and distant metastases at diagnosis. The C228T mutation was also associated with worse progression-free interval (PFI) in comparison to WT tumors (HR=5,04; P<0.001). This association remained significant in a multivariate analyses (HR=3.74, P=0.003) adjusting for BRAF-V600E status and ATA risk group. Our data indicate that TERT promoter mutations C228T and C250T have distinct transcriptional consequences in PTC, suggesting a greater oncogenic potential for the C228T mutation. TERT promoter mutation C228T may be a useful prognostic marker to identify patients at high risk of distant recurrence. Clinical data for the C250T mutation is still limited, with no evidence up to date to confirm its prognostic significance.

Survival Outcomes in Thyroid Cancer Patients with Co-Occurring Breast Cancer: Evidence of Mortality Risk Attenuation.

BACKGROUND: Previous studies have reported a strong correlation between breast cancer (BC) and thyroid cancer (TC) incidence. However, the clinical and oncological impact of these associations are not yet fully understood. Here, we aimed to explore the differences in clinicopathological characteristics between TC patients with and without BC, and the effect of a history of positive BC on TC survival. METHODS: We retrospectively compared the clinical characteristics and survival rates of patients with TC alone and those with TC and BC in a primary cohort at our institution and in a second cohort using the Surveillance, Epidemiology, and End Results (SEER) database. RESULTS: In our institutional cohort, survival rates were similar between patients with TC alone and those with TC-associated BC. However, using SEER data, we found that BC had a protective effect on TC patients and was associated with reduced TC mortality rates (hazard ratio [HR] = 0.72, 95% confidence interval [CI] 0.57 to 0.92; P = .026). After stratifying the TC patients according to co-occurring BC subtypes, we observed that higher survival rates were restricted to patients with coexisting luminal A BC (P = .015), which exhibit positive hormone receptors and do not express HER-2. CONCLUSION: These findings suggest that hormone pathways may play a role in the co-occurrence of thyroid and breast cancers. Patients with TC coexisting with luminal A BC have higher survival rates. However, further studies on the mechanisms underlying the association between BC and TC are warranted.

Neoadjuvant Treatment of Locally Advanced Thyroid Cancer: A Preliminary Latin American Experience.

Background: Surgical resection is not always achievable in thyroid cancer patients. Neoadjuvant therapy is rarely used, but recent trends favor multikinase inhibitors or selective tyrosine kinase inhibitors. These aim to reduce tumor volume, enabling previously unfeasible surgeries. Patients and Methods: Consecutive patients with locally advanced malignant thyroid tumors who received systemic therapies with a neoadjuvant intention were included in this retrospective multicenter case series conducted in five Latin American referral centers. Primary outcomes were pre- versus postneoadjuvant response evaluations using the Response Evaluation Criteria in Solid Tumors, feasibility of surgery, and completeness of resection. Secondary outcomes were mortality and status at the last visit. Results: Twenty-seven patients were included in this analysis. Patients with unresectable differentiated thyroid cancer (DTC) or poorly differentiated thyroid cancer (PDTC) received sorafenib (n = 6) or lenvatinib (n = 12), those with medullary thyroid cancer (MTC) were treated with vandetanib (n = 5) or selpercatinib (n = 1), and those with anaplastic thyroid cancer (ATC) harboring a BRAFV600E mutation (n = 3) received dabrafenib and trametinib. The median patient age was 66 years (range 12-82), and 52% of the patients were female. In patients with PTC and PDTC, the median reduction in the diameter of the primary tumor was 25% (range 0-100%) after a median of 6 months of treatment. Surgical intervention was performed in 10 (55%) of the patients. Among these, six patients (60%) achieved R0/R1 resection status. Six patients with MTC had a median reduction in tumor diameter of 24.5% (range 1-49) after a median treatment time of 9.5 months. Only one patient receiving selpercatinib, with a tumoral reduction of 25% could undergo surgery, resulting in an R2 resection due to extensive mediastinal extension. Three patients with ATC showed a median tumor diameter reduction of 42% (range 6.7-50) after a median treatment time of 2 months. Two patients underwent surgical intervention and achieved R1 and R2 resection, respectively. Conclusions: While neoadjuvant therapy achieved tumoral responses, surgical resection was feasible in 55% of DTC, 33% of ATC, and 16% of MTC patients, with R0/R1 resection in 26% of the cohort, underscoring the need for patient selection and further research in this area.

Active surveillance of nodal metastasis in differentiated thyroid carcinoma: a systematic review and meta-analysis.

PURPOSE: Cervical lymph nodes (LN) represent the most common site of recurrence in differentiated thyroid cancer (DTC), frequently requiring repeated interventions that contribute to increase morbidity to a usually indolent disease. Data on active surveillance (AS) of nodal metastasis are limited. Therefore, we performed a systematic review and meta-analysis to evaluate AS in nodal metastasis of DTC patients. METHODS: MEDLINE, EMBASE, and Cochrane databases were searched up to July 2023 for studies including DTC patients with metastatic LN who were followed up with AS. The primary outcome was disease progression, according to the study's definition. Additional outcomes were LN enlargement ≥3 mm, occurrence of new cervical metastasis, and conversion from AS to surgical treatment. RESULTS: The search identified 375 studies and seven were included, comprising 486 patients with metastatic nodal DTC. Most were female (69.5%) and had papillary thyroid cancer (99.8%). The mean AS follow-up ranged from 28-86 months. Following each study's definition of progression, the pooled incidence was 28% [95% confidence interval (CI), 20-37%]. The pooled incidence of LN growth ≥ 3 mm was 21% [95% CI, 17-25%] and the emergence of new LN sites was 19% [95% CI, 14-25%]. Combining growth of 3 mm and the emergence of new LN criteria, we found an incidence of 26% [95% CI, 20-33%]. The incidence of neck dissection during AS was 18% [95% CI, 12-26%]. CONCLUSIONS: AS seems to be a suitable strategy for selected DTC patients with small nodal disease, avoiding or postponing surgical reintervention. PROSPERO REGISTRATION: CRD42023438293.

Differentiated thyroid carcinoma: what the nonspecialists needs to know.

Differentiated thyroid carcinoma (DTC) accounts for most cases of thyroid cancer, and the heterogeneity of DTC requires that management decisions be taken by a multidisciplinary team involving endocrinologists, head and neck surgeons, nuclear medicine physicians, pathologists, radiologists, radiation oncologists, and medical oncologists. It is important for nonspecialists to recognize and refer patients with DTC who will benefit from a specialized approach. Recent advances in knowledge and changes in management of DTC call for the need to raise awareness on the part of these nonspecialist physicians, including general endocrinologists and medical oncologists at large. We provide an overview of diagnostic and therapeutic principles in DTC, especially those that bear direct implication on day-to-day management of these patients by generalists. Patients with DTC may be broadly categorized as having localized, locally persistent/recurrent, or metastatic disease. Current recommendations for DTC include a three-tiered system that classifies patients with localized disease into low, intermediate, or high risk of persistent or recurrent disease. Risk stratification should be performed at baseline and repeated on an ongoing basis, depending on clinical evolution. One of the overarching goals in the management of DTC is the need to personalize treatment by tailoring its modality and intensity according to ongoing prognostic stratification, evolving knowledge about the disease, and patient characteristics and preference. In metastatic disease that is refractory to radioactive iodine, thyroid tumors are being reclassified into molecular subtypes that better reflect their biological properties and for which molecular alterations can be targeted with specific agents.

Dual targeting of MAPK and PI3K pathways unlocks redifferentiation of Braf-mutated thyroid cancer organoids.

Thyroid cancer is the most common endocrine malignancy and several genetic events have been described to promote the development of thyroid carcinogenesis. Besides the effects of specific mutations on thyroid cancer development, the molecular mechanisms controlling tumorigenesis, tumor behavior, and drug resistance are still largely unknown. Cancer organoids have been proposed as a powerful tool to study aspects related to tumor development and progression and appear promising to test individual responses to therapies. Here, using mESC-derived thyroid organoids, we developed a BrafV637E-inducible model able to recapitulate the features of papillary thyroid cancer in vitro. Overexpression of the murine BrafV637E mutation, equivalent to BrafV600E in humans, rapidly triggers to MAPK activation, cell dedifferentiation, and disruption of follicular organization. BrafV637E-expressing organoids show a transcriptomic signature for p53, focal adhesion, ECM-receptor interactions, EMT, and inflammatory signaling pathways. Finally, PTC-like thyroid organoids were used for drug screening assays. The combination of MAPK and PI3K inhibitors reversed BrafV637E oncogene-promoted cell dedifferentiation while restoring thyroid follicle organization and function in vitro. Our results demonstrate that pluripotent stem cells-derived thyroid cancer organoids can mimic tumor development and features while providing an efficient tool for testing novel targeted therapies.

Not Only RET but NF1 and Chromosomal Instability Are Seen in Young Patients with Sporadic Medullary Thyroid Carcinoma.

Context: Genetic analysis of sporadic medullary thyroid carcinoma (MTC) has revealed somatic variants in RET, RAS, and occasionally other genes. However, around 20% of patients with sporadic MTC lack a known genetic driver. Objective: To uncover potential new somatic or germline drivers, we analyze a distinct cohort of patients with sporadic, very early-onset, and aggressive MTC. Methods: Germline and somatic DNA exome sequencing was performed in 19 patients, previously tested negative for germline RET variants. Results: Exome sequencing of 19 germline samples confirmed the absence of RET and identified an NF1 pathogenic variant in 1 patient. Somatic sequencing was successful in 15 tumors revealing RET variants in 80%, predominantly p.Met918Thr, which was associated with disease aggressiveness. In RET-negative tumors, pathogenic variants were found in HRAS and NF1. The NF1 germline and somatic variants were observed in a patient without a prior clinical diagnosis of neurofibromatosis type 1, demonstrating that the loss of heterozygosity of NF1 functions as a potential MTC driver. Somatic copy number alterations analysis revealed chromosomal alterations in 53.3% of tumors, predominantly in RET-positive cases, with losses in chromosomes 9 and 22 being the most prevalent. Conclusion: This study reveals that within a cohort of early-onset nonhereditary MTC, RET remains the major driver gene. In RET-negative tumors, NF1 and RAS are drivers of sporadic MTC. In addition, in young patients without a RET germline mutation, a careful clinical evaluation with a consideration of germline NF1 gene analysis is ideal to exclude Neurofibromatosis type 1 (NF1).

Classification of Thyroid Tumors Based on DNA Methylation Patterns.

Background: Alterations in DNA methylation are stable epigenetic events that can serve as clinical biomarkers. The aim of this study was to analyze methylation patterns among various follicular cell-derived thyroid neoplasms to identify disease subtypes and help understand and classify thyroid tumors. Methods: We employed an unsupervised machine learning method for class discovery to search for distinct methylation patterns among various thyroid neoplasms. Our algorithm was not provided with any clinical or pathological information, relying exclusively on DNA methylation data to classify samples. We analyzed 810 thyroid samples (n = 256 for discovery and n = 554 for validation), including benign and malignant tumors, as well as normal thyroid tissue. Results: Our unsupervised algorithm identified that samples could be classified into three subtypes based solely on their methylation profile. These methylation subtypes were strongly associated with histological diagnosis (p < 0.001) and were therefore named normal-like, follicular-like, and papillary thyroid carcinoma (PTC)-like. Follicular adenomas, follicular carcinomas, oncocytic adenomas, and oncocytic carcinomas clustered together forming the follicular-like methylation subtype. Conversely, classic papillary thyroid carcinomas (cPTC) and tall cell PTC clustered together forming the PTC-like subtype. These methylation subtypes were also strongly associated with genomic drivers: 98.7% BRAFV600E-driven cancers were PTC like, whereas 96.0% RAS-driven cancers had a follicular-like methylation pattern. Interestingly, unlike other diagnoses, follicular variant PTC (FVPTC) samples were split into two methylation clusters (follicular like and PTC like), indicating a heterogeneous group likely to be formed by two distinct diseases. FVPTC samples with a follicular-like methylation pattern were enriched for RAS mutations (36.4% vs. 8.0%; p < 0.001), whereas FVPTC- with PTC-like methylation patterns were enriched for BRAFV600E mutations (52.0% vs. 0%, Fisher exact p = 0.004) and RET fusions (16.0% vs. 0%, Fisher exact p = 0.003). Conclusions: Our data provide novel insights into the epigenetic alterations of thyroid tumors. Since our classification method relies on a fully unsupervised machine learning approach for subtype discovery, our results offer a robust background to support the classification of thyroid neoplasms based on methylation patterns.

Active Surveillance of Differentiated Thyroid Cancer Metastatic Cervical Lymph Nodes: A Retrospective Single-Center Cohort Study.

Background: The most frequent site of recurrence of differentiated thyroid cancer (DTC) is cervical lymph nodes (LNs), which often necessitates repeated surgical interventions and morbidity in a generally indolent disease. Data on active surveillance (AS) of small cervical nodal metastasis are still scarce, particularly in real-world clinical settings. In this study, we evaluated the DTC outcomes of AS of metastatic cervical LNs and explored factors associated with disease progression. Methods: We conducted a retrospective cohort study, including DTC patients with biopsy-proven metastatic cervical LNs, who were followed on AS in a tertiary care, university-based institution in Brazil. The inclusion criteria were cervical metastasis ≤2.0 cm and an AS duration of at least 6 months. We excluded lesions with aggressive histology, those in close proximity to or invading local structures. The primary outcome was disease progression (enlargement ≥3 mm in any diameter or a new cervical metastasis). Results: Data from 40 patients were analyzed. Most were female (77.5%) and had papillary thyroid cancer (97.5%). The mean age was 47.0 (± standard deviation 15.8) years. The 8th edition of the tumor, node, metastasis stage (TNM8) staging for DTC was as follows: 29 in stage I (74.4%), 8 in stage II (20.5%), and 2 in stage IV (5.0%). The median maximum LN diameter was 0.9 (interquartile range [IQR], 0.8-1.3) cm, and the median AS follow-up duration was 27.5 (IQR, 16.5-47.3) months. Disease progression occurred in 14 (35%) patients: 7 (17.5%) due to enlargement ≥3 mm, and 7 (17.5%) had new cervical metastasis. The cervical progression-free survival was 51.0 (confidence interval, 47.0-55.0) months. No demographic, oncological, or biochemical factors were associated with disease progression. Of the 14 patients with disease progression, 8 were referred for surgery. No permanent surgical complications were reported. Of the six patients who remained on AS despite disease progression, five showed no further progression during subsequent follow-up (range 6-40 months). Conclusions: We observed that most small metastatic cervical LNs remained stable and were safely managed with AS. Nevertheless, these observations are limited by the retrospective design, small sample size, and short follow-up. Further prospective and long-term studies are warranted.

An Undetectable Postoperative Calcitonin Level Is Associated with Long-Term Disease-Free Survival in Medullary Thyroid Carcinoma: Results of a Retrospective Cohort Study.

Background: Calcitonin measurement is widely used in the diagnosis, prognosis, and follow-up of patients with medullary thyroid carcinoma (MTC). The prognostic value of undetectable postoperative calcitonin (POCal) in long-term disease outcomes remains uncertain. Objective: The aim of this study is to evaluate POCal as a prognostic marker for long-term MTC disease status. Methods: A retrospective cohort study was carried out. We collected data from the medical records of patients with MTC attending two tertiary teaching hospitals. Patients were divided according to POCal into two groups: undetectable (below the detection limit) or detectable. The outcome was determined at the last medical visit and defined as disease free (undetectable calcitonin and no evidence of disease on imaging), persistent disease (detectable calcitonin with or without structural disease), or disease-related death. Results: Three hundred thirty-four MTC patients were included in the study. The mean age at diagnosis was 41.1 ± 18.6 years; 202 patients (60.5%) were women; and 167 patients (50.0%) had sporadic MTC. The median tumor size was 2.0 cm (1.1-3.5 cm); 164 patients (49.1%) had lymph node metastasis and 63 patients (18.9%) had distant metastasis. At the first postoperative evaluation (3-6 months after surgery), 141 patients had undetectable POCal (mean age = 37.9 years, 70.9% women, median tumor size 1.5 cm [0.7-2.5 cm]; 28 [19.9%] had lymph node metastasis and none had distant metastasis). After a median follow-up of 7.7 years (2.1-13.2 years), 127 (90.1%) of these patients were free of disease, whereas 14 (9.9%) had persistent biochemical disease with stable calcitonin levels. No patient with undetectable POCal died of the disease. In the detectable POCal group (mean age = 42.9 years, 52.8% women, median tumor size 3.0 cm [1.8-4.2 cm]; 136 [70.5%] had lymph node metastasis and 63 [32.6%] had distant metastasis), 18 (9.2%) patients achieved disease-free status, 51 (26.6%) had biochemical disease, and 61 (31.6%) had persistent structural disease. Sixty-three (32.6%) patients died of disease-related events. Further analysis using a multivariate model identified undetectable POCal as an independent prognostic variable for disease-free status (HR = 5.33, CI = 2.86-9.94; p < 0.001). Conclusions: POCal is a strong prognostic marker for long-term disease-free survival and might help define follow-up strategies for MTC patients.

Age-related variation in malignant cytology rates of thyroid nodules: insights from a retrospective observational study assessing the ACR TI-RADS.

OBJECTIVE: The influence of age on the malignant cytology rate of thyroid nodules remains uncertain. The American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) is currently used to guide subsequent investigations of thyroid nodules, regardless of clinical variables. This study aimed to investigate the impact of age on the malignant cytology rates of thyroid nodules and the diagnostic performance of ACR TI-RADS across different age groups. DESIGN: A retrospective, single-center, observational study. METHODS: Patients aged ≥ 20 years with thyroid nodules, who underwent fine-needle aspiration biopsy between 2012 and 2019 were evaluated. Ultrasound images were used to obtain the TI-RADS data. Malignancy was determined based on suspicious for malignancy (Bethesda V) and malignant (Bethesda VI) cytology results or malignancy in cell block analysis. RESULTS: A total of 1023 nodules from 921 patients (88.2% female) were analyzed. The median age was 58.5 (interquartile range [IQR], 41.1-66.6) years, and the median nodule size was 2.4 (IQR, 1.7-3.6) cm. Stratification by age revealed a decreasing prevalence of malignant cytology across subgroups of 20-39, 40-59, and ≥60 years (10.7%, 8.5%, and 3.7%, respectively; P = .002). After adjusting for sex, multinodularity, nodule size, and ACR TI-RADS category, we observed that each year of age reduced the OR for malignant cytology by 3.0% (95% CI: 0.7%-5.3%; P = .011). When comparing the subgroups of 20-39 and ≥60 years, the malignant cytology rate decreased by half in TI-RADS 4 (from 21.4% to 10.4%) and two-thirds in TI-RADS 5 (from 64.7% to 22.6%). CONCLUSIONS: Our study demonstrated that as patient age increased, the rate of malignant cytology in thyroid nodules decreased. Moreover, age significantly influences the malignancy rates of thyroid nodules classified according to the ACR TI-RADS.