Risk assessment for distant metastasis in differentiated thyroid cancer using molecular profiling: A matched case-control study

DNA Methylation Dynamics and Prognostic Implications in Metastatic Differentiated Thyroid Cancer

Background: Distant metastases (DM) are the leading cause of thyroid cancer-related death in patients with differentiated thyroid cancer (DTC). Despite significant progress in understanding DNA methylation in DTC, the methylation landscape of metastatic primary tumors and DM remains unclear. Our primary objective was to investigate DNA methylation dynamics during DTC progression, with a secondary goal of assessing potential clinical implications. Materials and Methods: We conducted a multicenter retrospective study in patients with DTC who underwent surgery at five university hospitals. We profiled DNA methylation in a discovery series of 97 samples (15 normal tissues, 30 non-metastatic [non-mDTC], and 35 metastatic [mDTC] primary DTC, and 17 paired metastases [lymph nodes and DM]). Results were validated in an independent series of 17 non-mDTC and 13 mDTC. We used receiver operating characteristic curve analysis to evaluate the identified prognostic CpG-signature. Results: DNA methylation alterations, mostly hypomethylation, increased progressively from primary tumors to DM, both in papillary (PTC) and follicular (FTC) thyroid carcinomas. Compared with normal tissue, non-metastatic primary PTC (non-mPTC) exhibited more hypomethylated than hypermethylated CpGs in contrast to non-metastatic primary FTC (non-mFTC). However, metastatic tumors, both mPTC and mFTC, predominantly exhibited hypomethylated CpGs. The overlap of differentially methylated CpGs (DMe-CpGs) was low between non-mPTC and non-mFTC (14% non-mPTC DMe-CpGs present in non-mFTC) but significantly higher between mPTC and mFTC (60% mPTC DMe-CpGs present in mFTC), underscoring the convergence of epigenetic changes during metastatic progression. The presence of many de novo DMe-CpGs from metastatic primary tumors (83% from mPTC and 40% from mFTC) in DM, including metachronous DM, supports the hypothesis that DM originates from a major subclone of the primary tumor. We identified and validated a 156-CpG signature in primary tumors capable of distinguishing between non-mDTC and mDTC, offering potential prognostic value for DM development regardless of histology. Conclusions: These results show a progressive increase in DNA methylation alterations, mainly hypomethylation, during PTC and FTC metastatic progression, suggesting a linear model, though the DNA methylation dynamics differs between the two histological types. The analysis of the 156-CpG signature in primary tumors may help identify patients with DTC at high risk for DM, enhancing a more personalized treatment.

The value of preoperative molecular testing in the management of Bethesda V and Bethesda VI thyroid tumors

The incidence of thyroid cancer has increased over recent years due to the fact that several diagnostic tools, such as neck ultrasound and fine-needle aspiration, are being ever more widely adopted. Lately, another modality which might provide significant information preoperatively on the aggressiveness of a thyroid tumor, its prognosis, and its recurrence rate is molecular testing. We reviewed the literature with regard to the role of preoperative molecular testing in patients with Bethesda V and Bethesda VI thyroid nodules and its impact on choice of the optimal treatment strategy. Several molecular mutations and alterations are associated with thyroid cancer and its biological behavior, such as BRAF-V600E, RET, and TERT promoter. Although the value of preoperative molecular testing for indeterminate nodules (Bethesda III and Bethesda IV) have been analyzed in numerous studies, the impact of preoperative molecular testing on Bethesda V and Bethesda VI thyroid nodules is not adequately described in the current literature. The preoperative recognition of specific molecular mutations, such as BRAFV600E and TERT promoter mutation, might provide more individualized management for thyroid cancer patients by altering the surgical approach and the extent of surgery for patients diagnosed with a more aggressive or iodine-resistant subtype of thyroid cancer.Thyroid cancer is characterized by multiple genetic mutations and alterations and, as a result, preoperative molecular testing of malignant nodules could be a very useful tool for surgeons, enabling them to decide on the most appropriate surgical approach for each patient.

Histopathologic and Clinical Features of Bethesda III-VI Nodules Harboring Isolated RAS Mutations

OBJECTIVE

Although thyroid tumors possessing isolated RAS mutations are generally considered to be indolent, the oncologic outcomes of tumors evaluated with comprehensive molecular testing have not been well characterized.

METHODS

We performed a retrospective cohort study of 368 consecutive patients with Bethesda III-VI thyroid nodules at a single institution (2016-2021) who underwent molecular testing with ThyroSeq v3. Patients with isolated RAS mutations were identified, and those with isolated BRAF V600E-mutated cancers were used as comparators. Outcomes of interest included rate of malignancy, high-risk histopathologic features, and structural disease recurrence.

RESULTS

A total of 50 patients (14%) had an isolated RAS-mutated nodule, of whom 41 underwent surgery (median age, 43 years; female, 83%). The malignancy rate on final pathology was 46%, whereas 32% of patients had noninvasive follicular thyroid neoplasm with papillary-like nuclear features and 22% had benign histopathology. In comparison, the isolated BRAF-mutated cohort (86 [24%] patients; median age, 45 years; female, 68%) had a 100% rate of malignancy. Only 2 (11%) of the isolated RAS patients with malignant histopathology had lymph node metastasis, compared with 34 (39%) of the BRAF cohort (P = .016). Over a median follow-up of 5 years, no patients with isolated RAS mutations had a structural recurrence compared with 5 patients (6%) in the isolated BRAF cohort.

CONCLUSION

Bethesda III-VI thyroid nodules with isolated RAS mutations have a low rate of aggressive histopathologic features and are unlikely to recur. Thyroid lobectomy may be sufficient treatment for these tumors.

TERT promoter mutations and additional molecular alterations in thyroid fine-needle aspiration specimens: A multi-institutional study with histopathologic follow-up

OBJECTIVES

TERT promoter mutations are not infrequently encountered in thyroid carcinomas; however, it is unclear if additional molecular alterations may play a role in determining tumor behavior.

METHODS

Fine-needle aspiration (FNA) specimens from 32 patients with TERT promoter mutations detected by ThyroSeq v3 from 4 institutions were included in the study. FNA diagnoses, molecular results, and surgical follow-up were retrospectively reviewed and analyzed.

RESULTS

There were 5 benign and 27 malignant neoplasms, including 7 high-grade thyroid carcinomas (HGCs) on histopathologic follow-up. Of 4 cases with an isolated TERT mutation, 3 (75%) cases were malignant. Of 17 cases harboring a co-occurring TERT mutation with 1 additional molecular alteration, 13 (76%) displayed malignancy on histopathologic follow-up. All 11 cases with TERT mutations plus 2 or more additional molecular alterations were malignant on follow-up. Furthermore, HGC was not seen in cases with an isolated TERT mutation, while 80% of cases harboring TERT mutations plus 3 additional molecular alterations showed HGC.

CONCLUSIONS

TERT promoter mutations are commonly associated with malignancy, particularly HGCs, when multiple co-occurring molecular alterations are present. However, TERT promoter mutations may occasionally be detected in benign thyroid neoplasms when encountered in isolation or with fewer than 2 additional molecular alterations.

The Surgical Management of Intracranial Metastasis Secondary to Follicular Cell-Derived Thyroid Carcinoma

BACKGROUND

Intracranial metastases (ICM) from follicular cell-derived thyroid carcinoma (FCDTC) are rare and are associated with a poor prognosis. The objective of this study is to report our experience in the surgical management of patients with ICM secondary to FCDTC.

METHODS

Patients with FCDTC who underwent surgical resection of an ICM were identified at our institution from 1998 to 2018.

RESULTS

Thirty-two patients were included in this study. Nineteen patients (59%) had involvement of the brain parenchyma only, 8 (25%) had a dural-based metastasis, 3 (9%) had a calvarial metastasis with dural extension, and 2 (6%) had a skull base metastasis with dural extension. In patients who had an R0-1 resection, the estimated lesional control at the site of resection was 91% at 3 years. However, overall ICM control was 37% at 3 years due to the progression of other ICM lesions. The 1-year disease-specific survival (DSS) was 87% and 5-year DSS was 37%.

CONCLUSIONS

ICM management in FCDTC is based on the size, number, and location of metastatic lesions. Complete resection of ICM may provide lesional control at the site of resection, however, DSS is poor due to the presence of other ICMs and metastases at multiple distant sites.

Molecular testing stratifies the risk of structural recurrence in high risk differentiated thyroid cancer: a retrospective cohort study

Background

High-risk differentiated thyroid cancer in 2015 American Thyroid Association risk stratification system (ATA-RSS) exhibits a significantly increased probability of recurrence and poor outcomes. This study aimed to investigate the molecular profiles of high-risk differentiated thyroid cancer and to assess the role of molecular testing in enhancing prognostic risk stratification.

Methods

In a single-center study conducted at Fujian Cancer Hospital, Fujian Province, China, a consecutive cohort of differentiated thyroid cancer patients identified as high-risk under 2015 ATA-RSS criteria were retrospectively assessed, spanning from November 1, 2019, to March 31, 2022. Molecular characterize groups were conducted using an 18-gene next-generation sequencing assay. Patients harboring mutations in the TERT promoter, TP53, or PIK3CA genes were categorized as the high molecular risk group, while all others were assigned to the non-high molecular risk group.

Results

Among the 108 cases, 32 (29.6%) fell into the high molecular risk group, characterized by a significantly older mean age (57.8 vs. 42.6 years, p < 0.001), larger tumor size (3.1 cm vs. 2.0 cm, p = 0.003), a higher incidence of aggressive pathological subtypes (43.8% vs. 7.9%, p < 0.001), and an increased occurrence of distant metastasis (34.4% vs. 7.9%, p = 0.001). Over a median follow-up period of 32.5 months, this high-risk group demonstrated an elevated risk of local recurrence (32.1% vs. 9.5%, HR: 3.18, 95% CI: 1.15-8.78) and metachronous distant metastasis (38.1% vs. 2.9%, HR: 12.54, 95% CI: 2.60-60.41). Multivariate COX regression analysis confirmed that molecular characterize groups (HR: 5.77, 95% CI: 2.18-15.23, p < 0.001) and tumor size (HR: 1.32, 95% CI: 1.00-1.74, p = 0.047) independently predicted recurrence-free survival.

Conclusion

ATA-RSS high-risk differentiated thyroid cancer often presents with late-hit genetic alterations, which are strongly associated with increased likelihood of structural recurrence. Molecular testing offers a precise approach to recurrence risk stratification in high-risk cases, enabling personalized follow-up and treatment strategies tailored to the specific prognostic profile.

Role of Publicly-Funded Molecular Testing in Surgical Management of Thyroid Nodules within Canadian Medicare: Clinical Assessment of ThyroSeqv3 Molecular Test Pilot Project at McGill University

ImportanceRecently, the Québec public health care system established a pilot project to cover costs of molecular testing for select patients with cytologically-indeterminate thyroid nodules.ObjectiveThis study aimed to evaluate the clinical utility of the ThyroSeqv3 molecular test pilot project at McGill University in surgical management of thyroid nodules within Canada's single-payer health care system.DesignMulticenter cohort study, in liaison with the Québec Health Ministry.SettingJewish General Hospital and Royal Victoria Hospital in Montreal, Canada.ParticipantsPatients with a Bethesda III or IV and TIRADS 3 or 4 thyroid nodule measuring between 1 and 4 cm in size on ultrasound were analyzed across pre- and post-pilot project phases.InterventionThe pre-pilot project surgical control group included patients who underwent surgical intervention, excluding those who opted for out-of-pocket molecular testing. The post-pilot project surgical exposure group encompassed participants in the pilot project, undergoing publicly-funded ThyroSeqv3 molecular testing and subsequent surgical intervention.Main Outcome MeasuresSurgical malignancy/noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) rate.ResultsA total of 314 patients qualified for the pilot project, with 207 (65.9%) having Bethesda III nodules and 107 (34.1%) having Bethesda IV nodules. Molecular testing yielded a result of negative in 238 (75.8%) cases and positive in 76 (24.2%) cases. Histopathology reports of positive patients who opted for surgery revealed a surgical malignancy/NIFTP rate of 73.1%. The surgical malignancy/NIFTP rate at our institution prior to the implementation of the pilot project for patients adhering to the inclusion criteria was statistically significantly lower at 47.9% (P = .0025).ConclusionsThe ThyroSeqv3 molecular test pilot project has improved upon physicians' traditional clinical practice by enabling a wider patient population to access this otherwise costly technology. It not only curtailed futile diagnostic hemithyroidectomies but also led to a more discerning allocation of surgeries, as corroborated by an increased surgical malignancy/NIFTP rate post-implementation.RelevanceThe results of our study suggest that publicly-funded molecular testing could contribute positively to the Canadian single-payer health care system by optimizing patient outcomes as well as fiscal policy.

Parsing the thyroid cytopathology suspicious for malignancy diagnosis through molecular-derived risk of malignancy and other related parameters: Insights into nodule characteristics and practice patterns

INTRODUCTION

Thyroid cytopathology cases with suspicious for malignancy (SFM) diagnosis often result in resection. However, molecular testing offers details that may provide additional insights. In this study, the molecular profiles of SFM cases from two institutions that routinely used ThyroSeq v3 (TSV3) were examined.

MATERIALS AND METHODS

Following institutional review board approval, SFM thyroid cytopathology cases with TSV3 results were retrieved from the databases of two institutions. Molecular information including molecular-derived risk of malignancy (MDROM), cytologic-histologic correlation data, and other related parameters were calculated. Statistical comparisons were made with a p <.05 considered significant.

RESULTS

The core data set comprised 114 SFM cases that passed TSV3 quality assurance. All TSV3 results were reported as positive or negative for genomic alterations and all except five cases provided a probability of malignancy estimate. The overall combined baseline MDROM of 75.7% (95% CI, 70.0-81.4) was comparable to the risk of malignancy (74%) published in the Bethesda System. There was a statistically significant difference between the combined MDROMs of resected and unresected cohorts (79.0% vs 58.6%; p = .0153). Interestingly, the MDROMs of the resected cohorts from the two institutions were statistically different (75.0% vs 85.3%; p = .020). Cytologic-histologic correlation revealed malignant outcome in 88.5% of resected cases.

CONCLUSIONS

Molecular analyses of SFM cases demonstrated higher risk genomic alterations that were associated with histologically overt neoplasms, resulting in increased malignancy outcome compared to baseline. MDROM analysis revealed differences in the cytopathologic practice patterns regarding follicular-patterned neoplasms at the two institutions.

Tumor size and molecular risk group are associated with differentiated thyroid cancer recurrence

BACKGROUND

The threshold at which active surveillance can be considered is variable, with some algorithms proposing nonoperative treatment for differentiated thyroid carcinomas ≤2 cm and lobectomy alone for lesions 2.1-4 cm. To inform both decision for and extent of initial surgery, we aim to evaluate whether molecular results can complement tumor size to identify differentiated thyroid carcinomas associated with disease recurrence.

METHODS

Patients from 2007-2013 and 2017-2021 who had initial thyroidectomy (differentiated thyroid carcinoma size 1-4 cm, clinical N0M0) were included. When available, molecular testing results were categorized into 3 previously described molecular risk groups (low, intermediate, and high). Primary outcome was structural recurrence.

RESULTS

Recurrence was diagnosed in 3.8% of 1,739 patients with differentiated thyroid carcinomas. Preoperative variables including size (1-2 cm vs 2.1-4 cm, P = .43), age >55 years (P = .92), and male sex (P = .31) were not associated with recurrence. Molecular testing results were available for 1,020, and after excluding molecular risk group high-risk differentiated thyroid carcinoma, structural recurrences were associated with molecular risk group intermediate risk (7.2% vs molecular risk group low, 0.7%, P < .001), and most likely in differentiated thyroid carcinoma, which were both 2.1-4 cm and molecular risk group intermediate risk (11.3% vs size 1-2 cm 5.8%, P = .04).

CONCLUSION

Overall, structural recurrences for differentiated thyroid carcinomas ≤4 cm were low (<5%) and molecuar testing was the only preoperative variable associated with recurrence. However, when molecular risk group intermediate risk was present, larger tumor size (2.1-4 cm) had a 2-fold greater risk of recurrence compared with tumors 1-2 cm, and size may still be helpful to guide management. When considering de-escalated treatment for the proposed guidelines with a cutoff of 2 cm, initial decision-making may be further optimized with identification of preoperative molecular risk groups.

BRAF V600E positive papillary thyroid carcinoma (TERT and TP53 mutation coexistence excluded): Correlation of clinicopathological features and the extent of surgical treatment and its complications

INTRODUCTION

Papillary thyroid carcinoma (PTC) frequently harbors the BRAF V600E mutation. Recent research suggests that aggressive behavior in BRAF V600E+ PTC may be due to an undetected mutation in the TERT gene. This study aims to observe the clinicopathological features of BRAF V600+ PTC and correlate them with surgical treatment complications.

METHODS

A retrospective analysis was conducted on the BRAF V600E+ PTC cohort from July 2019 to January 2023. The histopathological features and surgical treatment (total thyroidectomy - group A, total thyroidectomy + central block neck dissection - group B) complications were correlated. Patients with TERT and TP53 mutation were excluded. Next-generation sequencing and real-time PCR were used for genetic analysis.

RESULTS

Out of 121 PTCs, 65 cases showed BRAF V600E mutation with the following features: intracapsular spread (13.8%), extracapsular spread (27.7%), extrathyroidal spread (15.4%), multifocality (26.2%), angioinvasion (12.3%), and local metastasis (27.7%). The incidence of surgical complications in group A/B was: reversible recurrent laryngeal nerve (RLN) paresis 3.7/7.1%, RLN paresis permanent 0/2.4%, paresthesia 6.8/23.8%, hypocalcemia 36.4/61.9% on day 1 and 27.3/33.3% on day 3, and bleeding 2.3/9.5%. There was no significant difference in clinicopathological features between the BRAF V600E+ and BRAF V600E- PTC groups. Group B had a significantly higher incidence of hypoacalcaemia on postoperative day 1 (p = 0.047).

CONCLUSION

The BRAF V600E mutation will certainly remain important in the preoperative diagnosis of PTC. The more radical surgical procedures currently recommended may be abandoned in the future, particularly elective CLND, which has a higher risk of postoperative complications.

Evolving concepts in thyroid cytology

Concepts in thyroid diagnostics are evolving. As cytopathologists, we benefit from understanding the changes taking place in cytopathology practice as well as intersecting areas that may have implications for us. In this review, we discuss recent changes to 1. Classification systems, 2. Ancillary molecular testing modalities, and 3. Key metrics that affect thyroid cytopathology. The recent World Health Organization, Bethesda Thyroid Cytopathology, and American Joint Committee on Cancer classification systems have aspects that are designed to harmonize the clinical, cytopathologic, histomorphologic, and molecular findings for improved communication and patient management. New terminologies such as thyroid follicular nodular disease and low-risk follicular cell-derived thyroid neoplasms are introduced to reflect the subtle biologic nuances involving benign non-neoplastic and low-grade neoplastic conditions. The Bethesda Thyroid Cytopathology System has simplified its terminology, updated risk of malignancy estimates, and expanded the discussions on molecular testing, clinical and imaging assessments, and pediatric cytopathology. There is now a single term for each of the 6 diagnostic categories. The American Joint Committee on Cancer has refined the staging criteria to provide improved stratification of patient prognostication. Molecular testing using next-generation technology now offers large panels of markers that are sensitive for detecting the wide range of thyroid neoplasms. These panels were developed in North America and whether other regions of the world will choose similar tests remain to be seen. Finally, metrics such as molecular-derived risk of malignancy and molecular risk group may be viewed as surrogates of resection information and used to complement diagnostics, management, and quality assurance.

Thyroid Fine-Needle Aspiration: The Current and Future Landscape of Cytopathology

Thyroid cytology is a rapidly evolving field that has seen significant advances in recent years. Its main goal is to accurately diagnose thyroid nodules, differentiate between benign and malignant lesions, and risk stratify nodules when a definitive diagnosis is not possible. The current landscape of thyroid cytology includes the use of fine-needle aspiration for the diagnosis of thyroid nodules with the use of uniform, tiered reporting systems such as the Bethesda System for Reporting Thyroid Cytopathology. In recent years, molecular testing has emerged as a reliable preoperative diagnostic tool that stratifies patients into different risk categories (low, intermediate, or high) with varying probabilities of malignancy and helps guide patient treatment.

The Role of Molecular Markers in Thyroid Cancer Diagnostics and Treatment

Molecular testing for cytologically indeterminate thyroid nodules has demonstrated benefit by reducing the need for diagnostic thyroidectomies and reducing costs. Its use is currently recommended in practice guidelines from the American Thyroid Association and the American Association of Endocrine Surgeons when clinically appropriate. Moreover, there is growing evidence that molecular testing may provide prognostic information and can detect targetable genetic alterations which may expand treatment options for refractory advanced thyroid cancers.

Revisiting the Relationship Between Tumor Size and Risk in Well-Differentiated Thyroid Cancer

Introduction: Large tumor size is associated with poorer outcomes in well-differentiated thyroid cancer, yet it remains unclear whether size >4 cm alone confers increased risk, independent of other markers of aggressive disease. The goal of this study was to assess the relationship between tumor size, other high-risk histopathological features, and survival in well-differentiated thyroid cancer and to evaluate the significance of 4 cm as a cutoff for management decisions. Methods: Patients with well-differentiated thyroid cancer were identified from the National Cancer Database (2010-2015) and categorized by tumor size (i.e., small [≤4 cm] or large [>4 cm]) and presence of high-risk histopathological features (e.g., extrathyroidal extension). First, propensity score matching was used to identify patients who were similar across all other observed characteristics except for small versus large tumor size, and a multivariable Cox proportional hazards model was used to estimate the relationship between tumor size and survival. Second, we assessed whether the presence of high-risk features demonstrates conditional effects on survival based on the presence of tumor size >4 cm using an interaction term. Finally, additional models assessed the relationship between incremental 1 cm increases in tumor size and survival. Analyses were repeated using a validation cohort from the Surveillance, Epidemiology, and End Results Program (2008-2013). Results: Of 193,133 patients in the primary cohort, 7.9% had tumors >4 cm, and 30% had at least one high-risk feature. After matching, tumor size >4 cm was independently associated with worse survival (HR 1.63, p < 0.001). However, tumor size >4 cm and one or more other high-risk features together yielded worse survival than either size >4 cm alone (MMD: 0.70, p < 0.001) or other high-risk features alone (MMD: 0.49, p < 0.001). When assessed in 1 cm increments, the largest increases in hazard of death occurred at 2 cm and 5 cm, not 4 cm. Results from the validation cohort were largely consistent with our primary findings. Conclusions: Concomitant high-risk features confer worse survival than large tumor size alone, and a 4 cm cutoff is not associated with the greatest increase in risk. These findings support a more nuanced approach to tumor size in the management of well-differentiated thyroid cancer.

Prediction of the Aggressive Clinical Course of Papillary Thyroid Carcinoma Based on Fine Needle Aspiration Biopsy Molecular Testing

Molecular genetic events are among the numerous factors affecting the clinical course of papillary thyroid carcinoma (PTC). Recent studies have demonstrated that aberrant expression of miRNA, as well as different thyroid-related genes, correlate with the aggressive clinical course of PTC and unfavorable treatment outcomes, which opens up new avenues for using them in the personalization of the treatment strategy for patients with PTC. In the present work, our goal was to assess the applicability of molecular markers in the preoperative diagnosis of aggressive variants of papillary thyroid cancer. The molecular genetic profile (expression levels of 34 different markers and BRAF mutations) was studied for 108 cytology specimens collected by fine-needle aspiration biopsy in patients with PTC having different clinical manifestations. Statistically significant differences with adjustment for multiple comparisons (p < 0.0015) for clinically aggressive variants of PTC were obtained for four markers: miRNA-146b, miRNA-221, fibronectin 1 (FN1), and cyclin-dependent kinase inhibitor 2A (CDKN2A) genes. A weak statistical correlation (0.0015 < p < 0.05) was observed for miRNA-31, -375, -551b, -148b, -125b, mtDNA, CITED1, TPO, HMGA2, CLU, NIS, SERPINA1, TFF3, and TMPRSS4. The recurrence risk of papillary thyroid carcinoma can be preoperatively predicted using miRNA-221, FN1, and CDKN2A genes.

Genomic characterization of cervical lymph node metastases in papillary thyroid carcinoma following the Chornobyl accident

Childhood radioactive iodine exposure from the Chornobyl accident increased papillary thyroid carcinoma (PTC) risk. While cervical lymph node metastases (cLNM) are well-recognized in pediatric PTC, the PTC metastatic process and potential radiation association are poorly understood. Here, we analyze cLNM occurrence among 428 PTC with genomic landscape analyses and known drivers (131I-exposed = 349, unexposed = 79; mean age = 27.9 years). We show that cLNM are more frequent in PTC with fusion (55%) versus mutation (30%) drivers, although the proportion varies by specific driver gene (RET-fusion = 71%, BRAF-mutation = 38%, RAS-mutation = 5%). cLNM frequency is not associated with other characteristics, including radiation dose. cLNM molecular profiling (N = 47) demonstrates 100% driver concordance with matched primary PTCs and highly concordant mutational spectra. Transcriptome analysis reveals 17 differentially expressed genes, particularly in the HOXC cluster and BRINP3; the strongest differentially expressed microRNA also is near HOXC10. Our findings underscore the critical role of driver alterations and provide promising candidates for elucidating the biological underpinnings of PTC cLNM.

Performance of a multigene genomic classifier and clinical parameters in predicting malignancy in a Southeast Asian cohort of patients with cytologically indeterminate thyroid nodules

BACKGROUND

Most thyroid nodules are benign. It is important to determine the likelihood of malignancy in such nodules to avoid unnecessary surgery. The primary objective of this study was to characterize the genetic landscape and the performance of a multigene genomic classifier in fine-needle aspiration (FNA) biopsies of cytologically indeterminate thyroid nodules in a Southeast Asian cohort. The secondary objective was to assess the predictive contribution of clinical characteristics to thyroid malignancy.

METHODS

This prospective, multicenter, blinded study included 132 patients with 134 nodules. Molecular testing (MT) with ThyroSeq v3 was performed on clinical or ex-vivo FNA samples. Centralized pathology review also was performed.

RESULTS

Of 134 nodules, consisting of 61% Bethesda category III, 20% category IV, and 19% category V cytology, and 56% were histologically malignant. ThyroSeq yielded negative results in 37.3% of all FNA samples and in 42% of Bethesda category III-IV cytology nodules. Most positive samples had RAS-like (41.7%), followed by BRAF-like (22.6%), and high-risk (17.9%) alterations. Compared with North American patients, the authors observed a higher proportion of RAS-like mutations, specifically NRAS, in Bethesda categories III and IV and more BRAF-like mutations in Bethesda category III. The test had sensitivity, specificity, negative predictive value, and positive predictive value of 89.6%, 73.7%, 84.0%, and 82.1%, respectively. The risk of malignancy was predicted by positive MT and high-suspicion ultrasound characteristics according to American Thyroid Association criteria.

CONCLUSIONS

Even in the current Southeast Asian cohort with nodules that had a high pretest cancer probability, MT could lead to potential avoidance of diagnostic surgery in 42% of patients with Bethesda category III-IV nodules. MT positivity was a stronger predictor of malignancy than clinical parameters.

Characterizing Genetic Alterations Related to Radioiodine Avidity in Metastatic Thyroid Cancer

CONTEXT

Patients with differentiated thyroid cancer (DTC) with distant metastasis (DM) are usually not recognized as radioactive iodine (RAI)-refractory DTC in a timely manner. The elucidation of genetic features related to RAI uptake patterns may shed light on the early recognition of RAI-refractory DTC.

OBJECTIVE

This work aimed to elucidate the underlying molecular features behind different RAI uptake patterns.

METHODS

A total of 214 patients with DM-DTC were retrospectively included in the analysis. RAI uptake patterns were defined as initially RAI refractory (I-RAIR) and initially RAI avid (I-RAIA) according to the first post-treatment scan, then I-RAIA was further divided into continually RAIA (C-RAIA), partly RAIR (P-RAIR), and gradually RAIR (G-RAIR) according to subsequent scans. The molecular subtype groups-BRAFV600E mutated, RAS mutated, fusions, and others-were classified according to main driver genes status.

RESULTS

BRAF, TERT promoter, and TP53 mutations are more frequently detected in the I-RAIR pattern while RET fusions and RAS mutations are more frequent in the I-RAIA pattern. A late-hit mutation including TERT, TP53, or PIK3CA is more common in I-RAIR than that in I-RAIA (50.0% vs 26.9%, P = .001), particularly for those with RAS mutations in the I-RAIR group, always accompanied by TERT promoter. Isolated RET fusions accounts for 10% of I-RAIR. When compared among driver gene groups, BRAFV600E-mutated tumors have a higher rate of the I-RAIR pattern (64.4%) than RAS-mutated (4.5%, P < .001) and fusion-positive (20.7%, P < .001) tumors. In I-RAIA subgroups, BRAFV600E-mutated tumors have lower prevalence of the C-RAIA pattern than those with RAS mutation or fusions.

CONCLUSION

Patients with the I-RAIR pattern predominantly featured mutations of the BRAF and/or TERT promoter, of which RAS mutations were usually accompanied by late-hit mutations, while fusions mostly occurred alone.

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.

Current practice in intermediate risk differentiated thyroid cancer - a review

Although the overall prognosis for differentiated thyroid cancer (DTC) is excellent, a subset of patients will experience disease recurrence or may not respond to standard treatments. In recent years, DTC management has become more personalized in order to enhance treatment efficacy and avoid unnecessary interventions.In this context, major guidelines recommend post-surgery staging to assess the risk of disease persistence, recurrence, and mortality. Consequently, risk stratification becomes pivotal in determining the necessity of postoperative adjuvant therapy, which may include radioiodine therapy (RIT), the degree of TSH suppression, additional imaging studies, and the frequency of follow-up.However, the intermediate risk of recurrence is a highly heterogeneous category that encompasses various risk criteria, often combined, resulting in varying degrees of aggressiveness and a recurrence risk ranging from 5 to 20%. Furthermore, there is not enough long-term prognosis data for these patients. Unlike low- and high-risk DTC, the available literature is contradictory, and there is no consensus regarding adjuvant therapy.We aim to provide an overview of intermediate-risk differentiated thyroid cancer, focusing on criteria to consider when deciding on adjuvant therapy in the current context of personalized approach, including molecular analysis to enhance the accuracy of patient management.

[Molecular and other ancillary tests proposed by The Bethesda system for reporting thyroid cytopathology 2023]

For the first time the 2023 version of The Bethesda System for Reporting Thyroid Cytology dedicates a whole chapter (chapter 14) to ancillary studies almost exclusively represented by molecular testing. The latest data reported bring some evidence that molecular testing could help to optimize the diagnostic performance of « indeterminate » categories (AUS and NF). Other studies suggest a promising role to guide the management of suspicious of malignancy and malignant categories. Indeed, the recognition of prognostic and predictive biomarkers analyzed on cytological samples, regardless of how it is collected, has progressed thanks to advances in our knowledge of molecular abnormalities of thyroid tumors. The chapter 14 is presented here highlighting the current and emerging roles of « in-house » and commercialized molecular testing as presented by TSBRTC.

How to Manage Advanced Differentiated Thyroid Cancer: Step-by-Step Analysis from Two Italian Tertiary Referral Centers

BACKGROUND

Differentiated thyroid carcinoma (DTC) has an excellent prognosis; however, advanced disease is associated with a worse prognosis and is relatively common. Surgery followed by RAI treatment remains the mainstream treatment for a large majority of patients with high- and intermediate-risk DTC, but its benefits should be carefully weighed against the potential for harm. The aim of this paper is to critically review the experience in treating advanced DTC at two tertiary referral centers in Italy.

METHODS

Retrospective analysis of 300 patients who underwent surgery for ADTC over 30 years.

RESULTS

The complication rate was 50.33%. A total of 135 patients (45%) remained at regular follow-up, 118 (87.4%) were alive, while 17 (12.6%) were deceased. The mean overall survival at 12 years was 84.8% with a mean of 238 months. Eleven patients (8.1%) experienced a relapse after a median of 13 months.

CONCLUSIONS

ADTC patients adequately treated can achieve prolonged survival even in the case of metastasis or disease relapse. Patients with ADTC should be referred to high-volume centers with the availability of an extended multidisciplinary team to receive tailored treatment.

Role of Genetic Testing in the Management of Indeterminate Thyroid Nodules in the Indian Setting

The increased detection of thyroid nodules in the human population has led to an increase in the number of thyroid surgeries without an improvement in survival outcomes. Though the choice for surgery is straightforward in malignant thyroid nodules, the decision is far more complex in those nodules that get categorized into indeterminate thyroid nodules (ITN) by fine needle aspiration. Therefore, there is a pressing need to develop a tool that will aid in decision-making among the ITN. In this context, the development of various molecular testing (MT) panels has helped to confirm or rule out malignancy, reducing unnecessary surgeries and potentially guiding the extent of surgery as well. Currently, such tests are widely used among the Western population but these MT panels are not used by the South Asian population because of non-availability of validated panels and the high cost involved. There is a need to develop a suitable panel which is population-specific and validate the same. In this review, we would focus on current trends in the management of ITN among the South Asian population and how to develop a novel MT panel which is cost-effective, with high diagnostic accuracy obviating the need for expensive panels that already exist.

Molecular Diagnostics and [18F]FDG-PET/CT in Indeterminate Thyroid Nodules: Complementing Techniques or Waste of Valuable Resources?

Background: An accurate preoperative workup of cytologically indeterminate thyroid nodules (ITN) may rule out malignancy and avoid diagnostic surgery for benign nodules. This study assessed the performance of molecular diagnostics (MD) and 2-[18F]fluoro-2-deoxy-d-glucose ([18F]FDG)-positron emission tomography/computed tomography (PET/CT) in ITN, including their combined use, and explored whether molecular alterations drive the differences in [18F]FDG uptake among benign nodules. Methods: Adult, euthyroid patients with a Bethesda III or IV thyroid nodule were prospectively included in this multicenter study. They all underwent MD and an [18F]FDG-PET/CT scan of the neck. MD was performed using custom next-generation sequencing panels for somatic mutations, gene fusions, and copy number alterations and loss of heterozygosity. Sensitivity, specificity, negative and positive predictive value (NPV, PPV), and benign call rate (BCR) were assessed for MD and [18F]FDG-PET/CT separately and for a combined approach using both techniques. Results: In 115 of the 132 (87%) included patients, MD yielded a diagnostic result on cytology. Sensitivity, specificity, NPV, PPV, and BCR were 80%, 69%, 91%, 48%, and 57% for MD, and 93%, 41%, 95%, 36%, and 32% for [18F]FDG-PET/CT, respectively. When combined, sensitivity and specificity were 95% and 44% for a double-negative test (i.e., negative MD plus negative [18F]FDG-PET/CT) and 68% and 86% for a double-positive test, respectively. Concordance was 63% (82/130) between MD and [18F]FDG-PET/CT. There were more MD-positive nodules among the [18F]FDG-positive benign nodules (25/59, 42%, including 11 (44%) isolated RAS mutations) than among the [18F]FDG-negative benign nodules (7/30, 19%, p = 0.02). In oncocytic ITN, the BCR of [18F]FDG-PET/CT was mere 3% and MD was the superior technique. Conclusions: MD and [18F]FDG-PET/CT are both accurate rule-out tests when unresected nodules that remain unchanged on ultrasound follow-up are considered benign. It may vary worldwide which test is considered most suitable, depending on local availability of diagnostics, expertise, and cost-effectiveness considerations. Although complementary, the benefits of their combined use may be confined when therapeutic consequences are considered, and should therefore not routinely be recommended. In nononcocytic ITN, sequential testing may be considered in case of a first-step MD negative test to confirm that withholding diagnostic surgery is oncologically safe. In oncocytic ITN, after further validation studies, MD might be considered. Clinical Trial Registration: This trial is registered with ClinicalTrials.gov: NCT02208544 (August 5, 2014), https://clinicaltrials.gov/ct2/show/NCT02208544.

Clinical relevance of gene mutations and rearrangements in advanced differentiated thyroid cancer

BACKGROUND

Tumor genotyping is becoming crucial to optimize the clinical management of patients with advanced differentiated thyroid cancer (DTC); however, its implementation in clinical practice remains undefined. We herein report our single-center experience on molecular advanced DTC testing by next-generation sequencing approach, to better define how and when tumor genotyping can assist clinical decision making.

MATERIALS AND METHODS

We retrospectively collected data on all adult patients with advanced DTC who received molecular profiling at the IRCSS Sant'Orsola-Malpighi Hospital from 2008 to 2022. The genetic alterations were correlated with radioactive iodide refractory (RAI-R), RAI uptake/disease status, and time to RAI resistance (TTRR) development.

RESULTS

A significant correlation was found between RAI-R development and genetic alterations (P = 0.0001). About 48.7% of RAI-R cases were positive for TERT/TP53 mutations (as both a single event and comutations with other driver gene alterations, such as BRAF mutations, RAS mutations, or gene fusions), while the great majority of RAI-sensitive cases carried gene fusions (41.9%) or were wild type (WT; 41.9%). RAI uptake/disease status and time to TTRR were significantly associated with genetic alterations (P = 0.0001). In particular, DTC with TERT/TP53 mutations as a single event or as comutations displayed a shorter median TTRR of 35.4 months (range 15.0-55.8 months), in comparison to the other molecular subgroups. TERT/TP53 mutations as a single event or as comutations remained independently associated with RAI-R after Cox multivariate analysis (hazard ratio 4.14, 95% CI 1.51-11.32; P = 0.006).

CONCLUSIONS

Routine testing for genetic alterations should be included as part of the clinical workup, for identifying both the subset of more aggressive tumors and the subset of tumors harboring actionable gene fusions, thus ensuring the appropriate management for all patients with advanced DTC.

Sacral metastases in a patient with BRAF V600E+ papillary thyroid carcinoma

Lack of consensus exists on an algorithm to screen for synchronous distant metastases in patients presenting with papillary thyroid carcinoma (PTC). A 68-year-old male presented with a 3 cm supraclavicular neck mass. Computed tomography (CT) scan revealed a 1.3 cm left thyroid lobe nodule and 3 cm left level 3 and 4 lymphadenopathy. Ultrasound-guided fine needle aspiration was positive for PTC. Patient underwent total thyroidectomy and lymph node dissection with molecular testing confirming BRAF V600E+ PTC. Six weeks post-operatively, he developed left hip pain and numbness. Magnetic resonance imaging (MRI) revealed a large sacral mass and multiple bony lesions confirmed to be osseous metastases. Given the relatively rapid report of hip pain after surgery, metastases were likely synchronous at presentation and may have been detected with earlier suspicion. Further investigation is necessary to systematically stratify risk of synchronous distant metastases in patients with metastatic PTC.

Molecular Profiling of 50 734 Bethesda III-VI Thyroid Nodules by ThyroSeq v3: Implications for Personalized Management

CONTEXT

Comprehensive genomic analysis of thyroid nodules for multiple classes of molecular alterations detected in a large series of fine needle aspiration (FNA) samples has not been reported.

OBJECTIVE

To determine the prevalence of clinically relevant molecular alterations in Bethesda categories III-VI (BCIII-VI) thyroid nodules.

METHODS

This retrospective analysis of FNA samples, tested by ThyroSeq v3 using Genomic Classifier and Cancer Risk Classifier at UPMC Molecular and Genomic Pathology laboratory, analyzed the prevalence of diagnostic, prognostic, and targetable genetic alterations in a total of 50 734 BCIII-VI nodules from 48 225 patients.

RESULTS

Among 50 734 informative FNA samples, 65.3% were test-negative, 33.9% positive, 0.2% positive for medullary carcinoma, and 0.6% positive for parathyroid. The benign call rate in BCIII-IV nodules was 68%. Among test-positive samples, 73.3% had mutations, 11.3% gene fusions, and 10.8% isolated copy number alterations. Comparing BCIII-IV nodules with BCV-VI nodules revealed a shift from predominantly RAS-like alterations to BRAF V600E-like alterations and fusions involving receptor tyrosine kinases (RTK). Using ThyroSeq Cancer Risk Classifier, a high-risk profile, which typically included TERT or TP53 mutations, was found in 6% of samples, more frequently BCV-VI. RNA-Seq confirmed ThyroSeq detection of novel RTK fusions in 98.9% of cases.

CONCLUSION

In this series, 68% of BCIII-IV nodules were classified as negative by ThyroSeq, potentially preventing diagnostic surgery in this subset of patients. Specific genetic alterations were detected in most BCV-VI nodules, with a higher prevalence of BRAF and TERT mutations and targetable gene fusions compared to BCIII-IV nodules, offering prognostic and therapeutic information for patient management.

Molecular signature incorporating the immune microenvironment enhances thyroid cancer outcome prediction

Genomic and transcriptomic analysis has furthered our understanding of many tumors. Yet, thyroid cancer management is largely guided by staging and histology, with few molecular prognostic and treatment biomarkers. Here, we utilize a large cohort of 251 patients with 312 samples from two tertiary medical centers and perform DNA/RNA sequencing, spatial transcriptomics, and multiplex immunofluorescence to identify biomarkers of aggressive thyroid malignancy. We identify high-risk mutations and discover a unique molecular signature of aggressive disease, the Molecular Aggression and Prediction (MAP) score, which provides improved prognostication over high-risk mutations alone. The MAP score is enriched for genes involved in epithelial de-differentiation, cellular division, and the tumor microenvironment. The MAP score also identifies aggressive tumors with lymphocyte-rich stroma that may benefit from immunotherapy. Future clinical profiling of the stromal microenvironment of thyroid cancer could improve prognostication, inform immunotherapy, and support development of novel therapeutics for thyroid cancer and other stroma-rich tumors.

2023 European Thyroid Association Clinical Practice Guidelines for thyroid nodule management

With the widespread use of sensitive imaging techniques, which include neck visualization, a conspicuous number of thyroid nodules emerge and demand attention. Most lesions are benign, asymptomatic, and do not warrant treatment. In the case of cancer diagnosis, most are small, intrathyroidal and indolent neoplasms that can safely be managed conservatively. There is a pronounced need for more cost-effective, risk-adapted approaches to the management of this highly prevalent condition, taking the wishes of the patient into consideration. Thus, the present guidelines aim at providing a clinical practice guide for the initial workup and the subsequent management of adult individuals harboring thyroid nodules. Importantly, these guidelines are not intended to cover the management of thyroid malignancy. The manuscript and the specific recommendations were developed by reconciling the best available research evidence with the knowledge and clinical experience of the panelists and updating aspects of a number of previous European Thyroid Association guidelines.

Preoperative Evaluation of Thyroid Cancer: A Review of Current Best Practices

OBJECTIVE

The incidence of thyroid cancer has significantly increased in recent decades. Although most thyroid cancers are small and carry an excellent prognosis, a subset of patients present with advanced thyroid cancer, which is associated with increased rates of morbidity and mortality. The management of thyroid cancer requires a thoughtful individualized approach to optimize oncologic outcomes and minimize morbidity associated with treatment. Because endocrinologists usually play a key role in the initial diagnosis and evaluation of thyroid cancers, a thorough understanding of the critical components of the preoperative evaluation facilitates the development of a timely and comprehensive management plan. The following review outlines considerations in the preoperative evaluation of patients with thyroid cancer.

METHODS

A clinical review based on current literature was generated by a multidisciplinary author panel.

RESULTS

A review of considerations in the preoperative evaluation of thyroid cancer is provided. The topic areas include initial clinical evaluation, imaging modalities, cytologic evaluation, and the evolving role of mutational testing. Special considerations in the management of advanced thyroid cancer are discussed.

CONCLUSION

Thorough and thoughtful preoperative evaluation is critical for formulating an appropriate treatment strategy in the management of thyroid cancer.

Performance of multigene testing in cytologically indeterminate thyroid nodules and molecular risk stratification

Objective

Thyroid cancer is the third most prevalent cancer among females. Genetic testing based on next-generation sequencing may provide an auxiliary diagnosis to reduce cytologically diagnostic uncertainty. However, commercial multigene tests are not widely available and are not well-tested in the Chinese population.

Methods

In this study, we designed a multigene testing panel and evaluated its performance in 529 cytologically indeterminate thyroid nodules (Bethesda III, IV and V). The molecular data of the DNA mutations and RNA fusions of fine needle aspiration samples were reviewed in conjunction with a clinical diagnosis, pathological reports, and definitive surgery for retrospective analysis. Then, the molecular risk stratification was investigated for its accuracy in malignant risk prediction.

Results

The overall combined consistency revealed substantial agreement (Kappa = 0.726) with the sensitivity, specificity, positive predictive value, and negative predictive values of 97.80%, 82.14%, 98.99%, and 67.65%, respectively. The most common aberration was BRAFV600E (82.59%), followed by NRAS mutants (4.07%), RET fusions (3.70%), and KRAS mutants (3.15%). Two cases (0.44%) were categorized into a high-risk group, 426 cases (94.67%) were categorized into a BRAF-like group with totally histopathologic papillary patterned tumors, and 22 cases (4.89%) were categorized into a RAS-like group with 14 papillary and eight follicular patterned tumors when the cohort concurrent aberrations were excluded. Potentially aggressive features may be related to concurrent molecular alterations of BRAFV600E with TERTQ302R, and AKT1L52R, NRASG12C, NRASQ61R, and CCDC6-RET fusions.

Conclusions

This study provided a multigene panel for identifying benign nodules from cytologically indeterminate thyroid nodules to avoid unnecessary surgery. We provide further evidence for using molecular risk stratification as a promising predictor of disease outcomes. The results of this study may be limited by the extremely high prevalence of cancer in the cohort for clinical reference.

Advances in Molecular Profiling and Their Potential Influence on the Extent of Surgery in Well-Differentiated Thyroid Carcinoma (WDTC)

Thyroid cancer surgery has evolved dramatically with advances in our understanding of the biological behaviour of WDTC. Molecular profiling is shedding light on the subset that may behave aggressively. In an era when thyroid cancer management is becoming increasingly conservative, decision making regarding the extent of surgery must be objectively guided by molecular markers. The aim of the present article is to summarise the current published literature and provide possible practice recommendations. An online search for relevant published articles was performed using several databases. Title, abstract, and full-text screening, along with data extraction, was performed by two independent reviewers after the inclusion and exclusion criteria were defined. A total of 1241 articles were identified, and 82 relevant articles were extracted and scrutinised. BRAF V600E and TERT promoter mutations were found to be associated with an increased risk of disease recurrence and distant metastases. Several other mutations have been identified that enhance disease aggressiveness (such as RET/PTC, PTEN, and TP53). One of the most important determinants of the outcome in WDTC is the extent of surgical resection. The evolution of molecular testing has reached a stage of personalised incorporation into surgical practice. Guidelines for molecular testing and surgery in WDTC will need to be clearly defined, arguably representing the next chapter in the management of the disease.

Selection Criteria for Completion Thyroidectomy in Follicular Thyroid Carcinoma Using Primary Tumor Size and TERT Promoter Mutational Status

BACKGROUND

A stepwise surgical approach with hemithyroidectomy and completion thyroidectomy was used to achieve definite characterization of follicular thyroid carcinoma (FTC). Choosing appropriate candidates for completion thyroidectomy has been controversial.

OBJECTIVE

The aim of this study was to clarify the selection criteria for completion thyroidectomy using telomerase reverse transcriptase (TERT) promoter mutation.

METHODS

A total of 87 FTC patients who had information about TERT promoter mutation from August 1995 to November 2020 were investigated. The cumulative risk of initial distant metastasis, disease recurrence, and cancer-specific death according to primary tumor size in each of the World Health Organization (WHO) 2017 classifications were calculated.

RESULTS

Of the 87 patients, 8 (9.2%) had initial distant metastasis and 15 (17.2%) had persistent disease or developed structural recurrence. The threshold diameter for initial distant metastasis, disease recurrence, and cancer-specific death was 2 cm in minimally invasive FTC (MI-FTC) with mutant TERT (M-TERT) and in encapsulated angioinvasive FTC (EA-FTC) with M-TERT, while that in MI-FTC with wild-type TERT (WT-TERT) and EA-FTC with WT-TERT was 4 cm. The cumulative risk of initial distant metastasis, disease recurrence, and cancer-specific death according to primary tumor size in each WHO 2017 classification was significantly different only in patients with WT-TERT (p = 0.001, p = 0.019, and p = 0.005, respectively).

CONCLUSIONS

The data suggest 2 cm as a critical threshold diameter for performance of completion thyroidectomy in MI-FTC with M-TERT and EA-FTC with M-TERT. TERT promoter mutational status can help select candidates for completion thyroidectomy.

Molecular Testing Predicts Incomplete Response to Initial Therapy in Differentiated Thyroid Carcinoma without Lateral Neck or Distant Metastasis at Presentation: Retrospective Cohort Study

BACKGROUND

Molecular testing (MT) is emerging as a potential prognostic factor that can be available before treatment of differentiated thyroid carcinoma begins. Among patients eligible for either lobectomy or total thyroidectomy as their initial therapy, our study aim was to assess (1) if conventionally available preoperative factors are associated with incomplete response to initial therapy, and (2) if molecular testing (MT) results can be a surrogate for the ATA Risk Stratification System (RSS) to estimate risk of recurrence.

METHODS

The data of consecutive thyroid cancer patients without preoperative lateral neck disease or distant metastasis who underwent index thyroidectomy between November 1, 2017 and October 31, 2021 were reviewed. Logistic regression models including preoperative variables such as MT and/or the postoperatively available RSS were constructed to predict disease recurrence, either structural or biochemical. Model discrimination using the c-statistic and goodness-of-fit were compared.

RESULTS

Among 945 patients studied, 50 (5.2%) recurred with 18-month median follow up. Recurrences were detected in 17 (2.9%), 20 (6.7%), and 13 (22.8%) patients with RSS-Low, -Intermediate, and -High cancers, respectively (p<0.001). In multivariable analysis, only tumor size was associated with recurrence (OR 1.3, 95% CI 1.1-1.5). In a different model analyzing 440 (46.6%) patients with available MT results, recurrence was associated with both larger tumor size (OR 1.4, 95% CI 1.1-1.8) and MT results (p<0.001). Including MT improved the c-statistic by 27%, which was statistically no different than the model incorporating only the RSS (p=0.15).

CONCLUSIONS

Disease recurrence was observed across all ATA RSS categories in short-term follow-up, and tumor size was the only conventional preoperative factor associated with recurrence. When MT results were incorporated, they not only improved predictive ability beyond tumor size alone, but also yielded similar ability as the gold standard ATA RSS. Thus, MT results might aid the development of novel preoperative risk stratification algorithms.

Is There a Role for Molecular Testing for Low-Risk Differentiated Thyroid Cancer? A Cost-Effectiveness Analysis

Molecular testing for thyroid nodules has been rapidly developed in recent years, aiming to predict the presence of malignancy and aggressive features. While commonly utilized to predict malignancy, its role in guiding the management approach is still developing. The high cost of genetic tests and long-term sequences of thyroid cancer is limiting to real-life studies. Objective: To evaluate the cost effectiveness of molecular testing for low-risk differentiated thyroid cancer (lrDTC). Methods: We developed a Markovian decision tree model of a simulated lrDTC cohort, comparing two management strategies: (I) Conducting genetic tests (GT)-patients are stratified into three risk groups for distant metastasis by the identified molecular markers: low-, intermediate- and high-risk molecular profile; followed by management accordingly: patients with low-risk will undergo hemithyroidectomy (HT), patients with intermediate-risk will undergo total thyroidectomy (TT), and high-risk patients will undergo TT with central neck dissection; (II) Without genetic tests (wGT)-all patients will undergo HT according to the ATA recommendations for lrDTC. Outcomes were measured as quality-adjusted life years (QALYs) and costs of each strategy. Results: GT was found as cost effective, leading to a gain of 1.7 QALYs with an additional cost of $327 per patient compared to wGT strategy. This yielded an incremental cost-effectiveness ratio of $190 per QALY. Sensitivity analysis demonstrated robust results across the variables' ranges. The most impactful variable was the benefit from performing TT rather than HT for intermediate to high-risk patients. Conclusions: Our model found that molecular testing for lrDTC is cost-effective, allowing tailored management according to the patient's personal risk level reflected in the genetic profile, hence improving outcomes.

Molecular testing in fine-needle aspiration of thyroid nodules

BACKGROUND

Thyroid nodules are commonly faced by clinicians as palpable nodules or incidentally identified on imaging. Nodules that are found to be suspicious by imaging can be biopsied by fine needle aspiration, which can yield material for molecular testing to refine the diagnosis.

METHODS

The current literature concerning molecular testing in thyroid nodules including available commercial assays was reviewed and summarized.

RESULTS/CONCLUSIONS

Commonly encountered alterations include mutations in RAS, BRAF, TERT promoter, PTEN, and DICER1 as well as fusions of RET, ALK, PAX8-PPARγ, and NTRK. This article provides a summary of these molecular alterations, commercially available molecular assays, and general considerations for thyroid epithelial malignancies and benign thyroid nodules.

Association of comprehensive thyroid cancer molecular profiling with tumor phenotype and cancer-specific outcomes

BACKGROUND

Molecular testing improves the diagnostic accuracy of thyroid cancer. Whether specific molecular testing results are associated with tumor phenotype or provide prognostic information needs further delineation.

METHODS

Consecutive thyroid cancer patients after index thyroidectomy with ThyroSeq version 3 (Rye Brook, NY) molecular testing obtained on preoperative fine-needle aspiration or thyroidectomy specimens from patients with thyroid cancer were categorized into 3 molecular risk groups based on detected mutations, fusions, copy number alterations, and/or gene expression alterations and correlated with histopathology and recurrence, defined as biochemical or structural.

RESULTS

Of 578 patients, 49.9%, 37.5%, and 12.6% had molecular risk group-low, molecular risk group-intermediate, and molecular risk group-high cancers, respectively. With a median 19-month follow-up, 9.1% patients recurred. Compared with molecular risk group-low, molecular risk group-intermediate cancers were diagnosed in younger patients and more often had microscopic extrathyroidal extension, involved margins, and nodal disease. Compared with molecular risk group-intermediate, molecular risk group-high cancers were diagnosed in older patients and more often had gross extrathyroidal extension and vascular invasion. In multivariable analysis, recurrence was more likely in molecular risk group-high cancers than in molecular risk group-intermediate (hazard ratio = 4.0; 95% confidence interval, 1.9-8.6; P < .001) and more likely in molecular risk group-intermediate than in molecular risk group-low (hazard ratio = 5.0; 95% confidence interval, 2.0-12.5; P < .001).

CONCLUSION

Using modern comprehensive genotyping, the genetic profile of thyroid cancers can be categorized into 3 novel molecular risk groups that were associated with histopathologic phenotype and recurrence in short-term follow-up.

Identification of R-Spondin Gene Signature Predictive of Metastatic Progression in BRAFV600E-Positive Papillary Thyroid Cancer

Papillary thyroid carcinoma (PTC) is the most common malignancy of the thyroid gland and early stages are curable. However, a subset of PTCs shows an unusually aggressive phenotype with extensive lymph node metastasis and higher incidence of locoregional recurrence. In this study, we investigated a large cohort of PTC cases with an unusual aggressive phenotype using a high-throughput RNA sequencing (RNA-Seq) to identify differentially regulated genes associated with metastatic PTC. All metastatic PTC with mutated BRAF (V600E) but not BRAF wild-type expressed an up-regulation of R-Spondin Protein 4 (RSPO4) concomitant with an upregulation of genes involved in focal adhesion and cell-extracellular matrix signaling. Further immunohistochemistry validation confirmed the upregulation of these target genes in metastatic PTC cases. Preclinical studies using established PTC cell lines support that RSPO4 overexpression is associated with BRAF V600E mutation and is a critical upstream event that promote activation of kinases of focal adhesion signaling known to drive cancer cell locomotion and invasion. This finding opens up the potential of co-targeting B-Raf, RSPO and focal adhesion proteins as a pharmacological approach for aggressive BRAF V600E PTC.

Surgical Outcomes of Thyroid Nodules Positive for Gene Expression Alterations Using ThyroSeq V3 Genomic Classifier

ThyroSeq V3 (TsV3) tests for various genetic alterations, including gene expression alterations (GEAs), to improve diagnostic accuracy and clinical decision-making for indeterminate thyroid nodules. This study aimed to clarify the clinico-pathological features and outcomes of GEA-positive thyroid nodules, which have not yet been well-described in the literature. A retrospective chart review was performed whereby patients were included if they underwent thyroid surgery between January 2018 and May 2022 at two McGill University teaching hospitals and their surgery was preceded by pre-operative molecular TsV3 testing. In total, 75 of the 328 patients with thyroid nodules (22.9%) who underwent molecular testing and surgery were GEA-positive. On surgical pathology, GEA-positive nodules showed a significantly higher malignancy rate compared to their GEA-negative counterparts (90.7% vs. 77.7%, respectively, p = 0.011). Among those that were malignant, 48.5% had at least one aggressive pathological feature, including histological subtype, extra-thyroidal extension, or lymph node metastasis. BRAF V600E mutation had a significantly greater association with aggressive malignant GEA-positive nodules compared to non-aggressive ones (p < 0.001). This study demonstrates that GEA may be an effective diagnostic and prognostic tool for thyroid nodule management. However, further investigation is needed to characterize the clinico-pathological features of GEA in isolation and in association with other gene alterations.

Performance of a Multigene Genomic Classifier in Thyroid Nodules with Suspicious for Malignancy Cytology

Background: Molecular testing is increasingly used to refine the probability of cancer and assess recurrence risk in thyroid nodules with Bethesda III/IV fine needle aspiration (FNA) cytology. However, limited data exist for Bethesda V (suspicious for malignancy [SFM]) samples. This study evaluated the performance of ThyroSeq v3 (TSv3) in thyroid nodules with SFM cytology. Methods: In this single-institution retrospective cohort study, consecutive thyroid FNA samples diagnosed as SFM with TSv3 testing and known surgical outcome were identified. Clinical, pathology, and molecular findings were reviewed. The TSv3 Cancer Risk Classifier was used to determine molecular risk groups (MRGs). For test-negative cases diagnosed as cancer/noninvasive follicular thyroid neoplasm with papillary-like nuclear features, TSv3 was performed on the resected tumors. Results: Among 128 SFM samples studied, 100 (78.1%) were TSv3 positive, and 28 (21.9%) were negative. The cancer prevalence on surgery was 82.8%. Among test-positive samples, 95% were malignant and 5% benign. Among test-negative samples, 17 (60.7%) were benign and 11 (39.3%) malignant. Overall, TSv3 had a sensitivity of 89.6% (confidence interval; CI 82.4-94.1) and a specificity of 77.3% (CI 56.6-89.9). For a cancer prevalence of 50-75% expected in SFM cytology by the Bethesda system, the negative predictive value was expected to range from 71.2% to 88.1% and the positive predictive value from 79.8% to 92.2%. Among test-positive nodules, 20% were MRG-Low (mostly RAS-like alterations), 66% MRG-Intermediate (mostly BRAF-like alterations), and 14% MRG-High. Among patients with cancer, 65 (61.3%) were American Thyroid Association low risk, 25 (23.6%) intermediate risk, and 6 (5.7%) high risk. During the mean follow-up of 51.2 months (range: <1 to 470 months), 12 (13.0%) patients had disease recurrence, which was more common in MRG-High (54.6%) compared with MRG-Intermediate (9.5%) and MRG-Low (0%) cancers (p < 0.001). Upon reexamining tumors with false-negative results, half of evaluable cases had alterations likely missed due to limiting FNA sampling, and the remainder represented low-risk tumors. Potentially targetable alterations were identified in 10 samples. Conclusions: In this large series of SFM thyroid nodules, TSv3 further improved cancer prediction and detected RAS-like, BRAF-like, high-risk, and potentially targetable alterations, all of which may inform more optimal patient management. MRGs were associated with recurrence-free survival, offering potential preoperative cancer risk stratification.

Molecular testing of cytology specimens: overview of assay selection with focus on lung, salivary gland, and thyroid testing

Ancillary and molecular testing of cytopathology specimens has emerged as a reliable and useful tool to provide diagnostic information and treatment-related biomarker status for the management of cancer patients. The cytology specimens obtained through minimally invasive means have proven suitable testing substrates for a variety of ancillary tests, including immunohistochemistry, fluorescence in situ hybridization, as well as polymerase chain reaction and next generation sequencing molecular techniques. By focusing specifically on the cytology specimen, this review provides an overview of basic testing considerations and assay selection in addition to updates on the ancillary testing of cytologic tumor specimens from the lung, salivary gland, and thyroid.

DIAGNOSIS OF ENDOCRINE DISEASE: Usefulness of genetic testing of fine-needle aspirations for diagnosis of thyroid cancer

OBJECTIVE

Genetic testing is increasingly used to diagnose or rule out thyroid cancer in indeterminate fine-needle aspirations. This review evaluates the usefulness of these methods with considerations of advantages and limitations.

DESIGN

Given the diagnostic problem associated with the increasing incidental detection of indeterminate thyroid nodules in the context of thyroid cancer overtreatment, we consider the conditions and respective necessary settings for the role of genetic testing to improve presurgical malignancy risk stratification.

METHODS

We review diagnostic pathway requirements and commercially available molecular tests with their respective advantages and disadvantages and discuss the prerequisites required for local application and implementation including quality assurance for local ultrasound and cytopathology practices.

RESULTS

Recent improvements in available molecular diagnostic tests have brought high sensitivity and specificity in initial validation studies, but whether these promising results translate to other clinical settings depends on the quality of the local thyroid nodule diagnostic pathway.

CONCLUSIONS

Genetic testing can meaningfully improve presurgical malignancy risk assessment, but more work is needed to implement and use genetic testing effectively in local settings.

Clinical detection of "extremely low-risk" follicular thyroid carcinoma: A population-based study of 7304 patients

Background

Previous studies have not been consistent in the risk of metastasis in follicular thyroid carcinoma (FTC). Therefore, we conducted a large population study to stratify the risk of distant metastasis in FTC patients using only clinical parameters.

Methods

We extracted FTC patients from The Surveillance, Epidemiology, and End Results (SEER) database and divided them into training and validation cohorts.

Results

The two cohorts consisted of 4913 and 2391 patients, respectively. We developed a nomogram and risk table based on a logistic regression model using algorithm-selected variables. Receiver Operating Characteristic (ROC) analyses showed high discriminatory power in the training and validation cohorts (Area under the curve [AUC] of 0.85 and 0.84, respectively). Extremely low, low, intermediate, and high-risk groups had 0.3%, 1%, 3.5%, and 16.7% risk of distant metastasis, respectively.

Conclusions

Our risk scoring table can separates patients into four risk groups and efficiently detect patients with almost no risk of metastasis.

Mutational status may supersede tumor size in predicting the presence of aggressive pathologic features in well differentiated thyroid cancer

Background

In clinical practice, thyroid tumor size plays a critical role in the staging of thyroid malignancies and in the selection of nodules that should undergo ultrasound-guided fine-needle aspiration. Thyroid tumor size is influenced by the elapsed time since the beginning of oncogenesis and by the presence of somatic mutations driving growth, such as BRAF^V600E mutations, associated with aggressive phenotypes, and RAS-like mutations, associated with more indolent behavior. Although large nodules are often considered to be more alarming, the true impact of tumor size on prognosis remains controversial. The aim of this study was to assess the relationship between mutational status, tumor size and aggressiveness, with emphasis on BRAF^V600E and RAS-like mutations.

Method

We conducted a multicentric retrospective chart review in Montréal, Canada, of all patients who underwent thyroid surgery between January 2016 and December 2020, with well-differentiated thyroid cancer on final pathology, and who had undergone molecular testing revealing the presence of BRAF^V600E mutations or RAS-like mutations (NRAS, HRAS or KRAS).

Results

We included 214 cases. There were 117 (54.7%) cases of BRAF^V600E and 97 (45.3%) cases of RAS-like mutations. The BRAF^V600E group was statistically associated with a smaller mean tumor size when compared with the RAS group of 1.55 cm and 2.04 cm, respectively. In a multivariate model, tumors with BRAF^V600E mutations were also more likely to display aggressive pathological features, including extra-thyroidal extension, lymph node metastasis, columnar cell features, tall cell histology, or hobnail histology (OR 26.69; 95% CI 11.15–70.81). In contrast, tumor size was not associated with pathologic aggressive features on multivariate analysis (OR 0.81; 95% CI 0.54–1.22).

Conclusion

This study demonstrates that thyroid tumors expressing BRAF^V600E mutations correlate with aggressive pathologic features more than tumors expressing RAS-like mutations. When comparing tumors with BRAF^V600E and RAS-like mutations, the former were found to be smaller. As a result of this finding, this study suggests that molecular alterations may better predict aggressive pathologic features than the size of the tumor.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s40463-022-00559-9.

Risk assessment for distant metastasis in differentiated thyroid cancer using molecular profiling: A matched case-control study

Background

Risk stratification for patients with differentiated thyroid cancer (DTC) is based primarily on pathologic tumor characteristics. Accurate preoperative prognostication could allow for more informed initial surgical recommendations, particularly among patients at a higher risk for distant metastasis (DM). The objective of this study was to characterize the genetic profile of DTC with DM and to validate a molecular‐based risk stratification.

Methods

A case‐control study design was used to analyze patients who had DTC with DM (n = 62) and a propensity matched cohort of patients who had DTC without DM after at least 5 years of follow‐up using the ThyroSeq version 3 targeted next‐generation sequencing assay. The results were classified into high‐risk, intermediate‐risk, and low‐risk of aggressive disease.

Results

Most patients who had DTC with DM (66%) had a late‐hit mutation in TERT, TP53, or PIK3CA. After propensity matching by age, tumor size, and sex, the high‐risk molecular profile had strong association with DM (high‐risk vs intermediate‐risk: odds ratio, 25.1; 95% CI, 3.07‐204.4; P < .001; high‐risk vs low‐risk: odds ratio, 122.5; 95% CI, 14.5‐1038.4; P < .001). Overall, molecular risk categories were associated with DM risk, with a concordance index of 0.836 (95% CI, 0.759‐0.913), which remained consistent after internal validation. Within the range of 5% to 10% of DM observed in DTC, the expected probability of DM would be 0.2% to 0.4% for the low‐risk molecular profile, 4.7% to 9.4% for the intermediate‐risk molecular profile, and 19.3% to 33.5% for the high‐risk molecular profile.

Conclusions

In this matched case‐control study, genetic profiling using an available molecular assay provided accurate and robust risk stratification for DM in patients with DTC. The availability of preoperative prognostication may allow tailoring treatment for patients with DTC.

In this matched case‐control study, comprehensive genetic profiling provides accurate and robust risk stratification for distant metastasis in patients with differentiated thyroid cancer. The availability of preoperative prognostication may allow for molecular‐directed treatment recommendations to tailor care for these patients.