Molecular testing for indeterminate thyroid nodules: Performance of the Afirma gene expression classifier and ThyroSeq panel

Preoperative evaluation of thyroid nodules - Diagnosis and management strategies

Thyroid cancer is the most common endocrine malignancy, with increasing incidence over the past few decades. Fine needle aspiration (FNA) biopsy is the gold standard for preoperative diagnosis of thyroid malignancies. Nevertheless, this method renders indeterminate results in up to 30% of the cases. Therefore, these patients are often referred to unnecessary surgery to establish the diagnosis. To improve the accuracy of preoperative diagnosis, several other ways, such as ultrasonography, elastography, immunohistochemical analysis, genetic testing, and core needle biopsy, have been developed and can be used either in association with or as an alternative to FNA. This review aims to evaluate all these diagnostic tools to determine the most appropriate way of managing thyroid nodules and subsequently improve the selection of cases referred to surgery.

Zinc in microscopic calcifications isolated from thyroid fine needle aspiration may serve as a biomarker of thyroid nodule malignancy: A promising proof-of-concept

Thyroid nodules (TNs) are common neck ultrasonography (US) findings, yet only 5-10% of these nodules harbor thyroid cancer (TC). When US characteristics are consistent with an intermediate or high suspicion for TN malignancy, fine needle aspiration for cytology (FNAC) is indicated. The main limitation of FNAC is that cytological results can be indeterminate in up to 30% of cases, necessitating reevaluation through repeated FNAC, expensive molecular testing, or diagnostic thyroid lobe resection. As such, there is a need for further refinement of current diagnostic algorithms for TNs without subjecting patients to additional invasive procedures. As calcifications detected during thyroid US are considered a high-risk feature for malignancy, we used the material remaining following routine thyroid FNAC to isolate microscopic calcifications (MCs). We then characterized the elemental composition, morphology, and crystal phases of these MCs, ultimately revealing differences between the MCs from benign and malignant TNs. Specifically, thyroid MCs were identified as calcium phosphate crystals containing varying levels of magnesium, sodium, iron, and zinc. MCs obtained from malignant TNs, mainly papillary thyroid carcinoma, were composed of sub-micrometer spherical particles, whereas MCs from benign TNs consisted of faceted particles. While samples from most patients with a final diagnosis of malignant TNs (50% of them with indeterminate cytology) harbored zinc-containing MCs, zinc was largely absent in MCs from benign TNs (23% with indeterminate or non-diagnostic cytology). Together, these data suggest that the presence of zinc in MCs isolated from samples collected during routine FNAC may potentially offer value as a biomarker of TN malignancy. STATEMENT OF SIGNIFICANCE: As up to 40% of patients assessed for thyroid malignancy do not receive a definite diagnosis following thyroid nodule (TN) fine needle aspiration (FNA), there is a pressing need to improve the accuracy of current diagnostic algorithms. Chemical analyses of microscopic calcifications (MCs) may serve as a diagnostic target. We developed a straightforward protocol to chemically characterize MCs from excess material collected from TNs during routine FNA and found that these MCs differed between benign and malignant TNs. Specifically, zinc in TN-derived MCs may indicate a higher nodule malignancy risk, thus increasing the diagnostic accuracy of the FNA procedure, reducing the need for recurrent biopsies and diagnostic surgical procedures, and decreasing the costs, uncertainty, and stress faced by affected patients.

Non-invasive follicular thyroid neoplasm with papillary-like nuclear feature: clinical, pathological, and molecular update 5 years after the nomenclature revision

The term non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) was proposed in 2016 and incorporated as a new entity in the World Health Organization (WHO) classification of tumours of endocrine organs in 2017. Since then, there has been debate regarding the histological criteria for the diagnosis, the need for molecular studies or the risk of lymph node metastasis or recurrence associated with this entity. Over the years, the concept of NIFTP evolved, now including both small (<1 cm) and large (>4 cm) tumours and oncocytic lesions. On the other hand, recent data on NIFTP in the setting of thyroid follicular nodular disease or frequent coexistence of malignant tumours raised concerns regarding the follow-up of these patients. Today, both pathologists and clinicians still face several challenges in the diagnosis, treatment, and follow-up of patients with NIFTP.

Assessing Bias and Limitations of Clinical Validation Studies of Molecular Diagnostic Tests for Indeterminate Thyroid Nodules: Systematic Review and Meta-Analysis

Background: Molecular tests for thyroid nodules with indeterminate fine needle aspiration results are increasingly used in clinical practice; however, true diagnostic summaries of these tests are unknown. A systematic review and meta-analysis were completed to (1) evaluate the accuracy of commercially available molecular tests for malignancy in indeterminate thyroid nodules and (2) quantify biases and limitations in studies that validate those tests. Summary: PubMed, EMBASE, and Web of Science were systematically searched through July 2021. English language articles that reported original clinical validation attempts of molecular tests for indeterminate thyroid nodules were included if they reported counts of true-negative, true-positive, false-negative, and false-positive results. We performed screening and full-text review, followed by assessment of eight common biases and limitations, extraction of diagnostic and histopathological information, and meta-analysis of clinical validity using a bivariate linear mixed-effects model. Forty-nine studies were included. Meta-analysis of Afirma Gene expression classifiers (GEC; n = 38 studies) revealed a sensitivity of 0.92 (confidence interval: 0.90-0.94), specificity of 0.26 (0.20-0.32), negative likelihood ratio (LR-) of 0.32 (0.23-0.44), positive LR+ of 1.24 (1.15-1.35), and area under the curve (AUC) of 0.83 (0.74-0.89). Afirma Genomic Sequencing Classifier (GSC; n = 10) had a sensitivity of 0.94 (0.89-0.96), specificity of 0.38 (0.27-0.50), LR- of 0.18 (0.10-0.30), LR+ of 1.52 (1.28-1.87), and AUC of 0.91 (0.62-0.92). ThyroSeq v1 and v2 (n = 10) had a sensitivity of 0.86 (0.82-0.90), specificity of 0.74 (0.59-0.85), LR- of 0.19 (0.13-0.26), LR+ of 3.52 (2.08-5.92), and AUC of 0.86 (0.81-0.90). ThyroSeq v3 (n = 6) had a sensitivity of 0.92 (0.86-0.95), specificity of 0.41 (0.18-0.69), LR- of 0.24 (0.09-0.62), LR+ of 1.67 (1.09-2.98), and AUC of 0.90 (0.63-0.92). Fourteen percent of studies conducted a blinded histopathologic review of excised thyroid nodules, and 8% made the decision to go to surgery blind to molecular test results. Conclusions: Meta-analyses reveal a high diagnostic accuracy of molecular tests for thyroid nodule assessment of malignancy risk; however, these studies are subject to several limitations. Limitations and their potential clinical impacts must be addressed and, when feasible, adjusted for using valid statistical methodologies.

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.

Classification of follicular-patterned thyroid lesions using a minimal set of epigenetic biomarkers

OBJECTIVE

The minimally invasive fine-needle aspiration cytology (FNAC) is the current gold standard for the diagnosis of thyroid nodule malignancy. However, the correct discrimination of follicular neoplasia often requires more invasive diagnostic techniques. The lack of suitable immunohistochemical markers to distinguish between follicular thyroid carcinoma and other types of follicular-derived lesions complicates diagnosis, and despite most of these tumours being surgically resected, only a small number will test positive for malignancy. As such, the development of new orthogonal diagnostic approaches may improve the accuracy of diagnosing thyroid nodules.

DESIGN

This study includes a retrospective, multi-centre training cohort including 54 fresh-frozen follicular-patterned thyroid samples and two independent, multi-centre validation cohorts of 103 snap-frozen biopsies and 33 FNAC samples, respectively.

METHODS

We performed a genome-wide genetic and epigenetic profiling of 54 fresh-frozen follicular-patterned thyroid samples using exome sequencing and the Illumina Human DNA Methylation EPIC platform. An extensive validation was performed using the bisulfite pyrosequencing technique.

RESULTS

Using a random forest approach, we developed a three-CpG marker-based diagnostic model that was subsequently validated using bisulfite pyrosequencing experiments. According to the validation cohort, this cost-effective method discriminates between benign and malignant nodules with a sensitivity and specificity of 97 and 88%, respectively (positive predictive value (PPV): 0.85, negative predictive value (NPV): 0.98).

CONCLUSIONS

Our classification system based on a minimal set of epigenetic biomarkers can complement the potential of the diagnostic techniques currently available and would prioritize a considerable number of surgical interventions that are often performed due to uncertain cytology.

SIGNIFICANCE STATEMENT

In recent years, there has been a significant increase in the number of people diagnosed with thyroid nodules. The current challenge is their etiological diagnosis to discount malignancy without resorting to thyroidectomy. The method proposed here, based on DNA pyrosequencing assays, has high sensitivity (0.97) and specificity (0.88) for the identification of malignant thyroid nodules. This simple and cost-effective approach can complement expert pathologist evaluation to prioritize the classification of difficult-to-diagnose follicular-patterned thyroid lesions and track tumor evolution, including real-time monitoring of treatment efficacy, thereby stimulating adherence to health promotion programs.

Pregnancy-associated plasma protein A mRNA expression as a marker for differentiated thyroid cancer: results from a "surgical" and a "cytological" series

PURPOSE

Pregnancy-associated plasma protein A (PAPPA) is a metalloproteinase initially described for its role during pregnancy. PAPPA regulates IGF ligands 1 (IGF1) bioavailability through the degradation of IGF-binding protein 4 (IGFBP4). After the cleavage of IGFBP4, free IGF1 is able to bind IGF1 receptors (IGF1R) triggering the downstream signaling. Recently, PAPPA expression has been linked with development of several cancers. No data have been published on thyroid cancer, yet.

METHODS

We evaluated PAPPA, insulin-like growth factor (IGF1), IGF1 receptors (IGF1R) and IGF-binding protein 4 (IGFBP4) mRNA expression levels in a "Surgical series" of 94 thyroid nodules (64 cancers, 16 follicular adenomas and 14 hyperplastic nodules) and in a "Cytological series" of 80 nodules from 74 patients underwent to fine-needle aspiration cytology (FNAC). In tissues, PAPPA was also evaluated by western blot.

RESULTS

We found that PAPPA expression was increased in thyroid cancer specimen at mRNA and protein levels and that, adenomas and hyperplastic nodules had an expression similar to normal tissues. When applied on thyroid cytologies, PAPPA expression was able to discriminate benign from malignant nodules contributing to pre-surgical classification of the nodules. We calculated a cut-off with a good specificity (91%) which reached 100% when combined with molecular biology.

CONCLUSION

These results show that PAPPA could represent a promising diagnostic marker for differentiated thyroid cancer.

Comparison of Afirma GEC and GSC to Nodules Without Molecular Testing in Cytologically Indeterminate Thyroid Nodules

Background

Analysis of cytologically indeterminate thyroid nodules with Afirma Gene Expression Classifier (GEC) and Genomic Sequencing Classifier (GSC) can reduce surgical rate and increase malignancy rate of surgically resected indeterminate nodules.

Methods

Retrospective cohort analysis of all adults with cytologically indeterminate thyroid nodules from January 2013 through December 2019. We compared surgical and malignancy rates of those without molecular testing to those with GEC or GSC, analyzed test performance between GEC and GSC, and identified variables associated with molecular testing.

Results

468 indeterminate thyroid nodules were included. No molecular testing was performed in 273, 71 had GEC, and 124 had GSC testing. Surgical rate was 68% in the group without molecular testing, 59% in GEC, and 40% in GSC. Malignancy rate was 20% with no molecular testing, 22% in GEC, and 39% in GSC (P = 0.022). GEC benign call rate (BCR) was 46%; sensitivity, 100%; specificity, 61%; and positive predictive value (PPV), 28%. GSC BCR was 60%; sensitivity, 94%; specificity, 76%; and PPV, 41%. Those with no molecular testing had larger nodule size, preoperative growth of nodules, and constrictive symptoms and those who underwent surgery in the no molecular testing group had higher body mass index, constrictive symptoms, higher Thyroid Imaging Reporting and Data System and Bethesda classifications. Type of provider was also associated with the decision to undergo surgery.

Conclusion

Implementation of GEC showed no effect on surgical or malignancy rate, but GSC resulted in significantly lower surgical and higher malignancy rates. This study provides insight into the factors that affect the real-world use of these molecular markers preoperatively in indeterminate thyroid nodules.

Single Institution Experience with Afirma and Thyroseq Testing in Indeterminate Thyroid Nodules

Background: Thyroid nodules are a very common often incidental finding on physical examination or imaging. Of those who undergo fine needle aspiration, cytology is indeterminate in up to 15%. Molecular testing is increasingly being used to help identify which nodules may be high risk for malignancy and guide management with regard to clinical follow-up or surgical intervention. Recently there has been an increase in publication of independent studies assessing the performance of these molecular tests and comparing "real-world" data with the validation studies. Methods: This retrospective study identified all thyroid nodules at our institution that had Afirma gene expression classifier (GEC), genomic sequencing classifier (GSC), or Thyroseq v3 molecular testing from January 2014 to January 2020 and compared measurements of test performance between them at our institution, and then with the original validation studies and other published institutional data. Results: Overall, the benign call rate was highest in the Afirma GSC group (78%) compared with the GEC group (60%) and Thyroseq group (66%). Surgical histopathology revealed malignancy in 6 of 31of biopsied nodules in the GEC group, 8 of 13 in the GSC group, and 3 of 16 in the Thyroseq v3 group. Based on our data, the GSC specificity (73.7%) and positive predictive value (PPV) (61.5%) were higher than the GEC specificity (60.4%) and PPV (22.2%) as well as Thyroseq v3 specificity (55.2%) and PPV (18.8%). Conclusions: From our short-term institutional experience, we found that the GSC classified more cytologically indeterminate nodules as benign compared with the Afirma GEC, and had improved specificity and PPV, which is similar to the validation study and other institutions' reported experiences. We also found that the Thyroseq v3 was similar to the Afirma GEC in terms of specificity and PPV, both of which are much lower than the validation studies.

Repeat Fine Needle Aspiration Cytology Refines the Selection of Thyroid Nodules for Afirma Gene Expression Classifier Testing

Background: Molecular testing (MT) refines risk stratification for thyroid nodules that are indeterminate for cancer by fine needle aspiration (FNA) cytology. Criteria for selecting nodules for MT vary and remain largely untested, raising questions about the best strategy for maximizing the usefulness of MT while minimizing the harms of overtesting. We used a unique data set to examine the effects of repeat FNA cytology-based criteria for MT on management decisions and nodule outcomes. Methods: This was a study of adults (age 25-90 years; 281 women and 72 men) with cytologically indeterminate (Bethesda III/IV) thyroid nodules who underwent repeat FNA biopsy and Afirma Gene Expression Classifier (GEC) testing (N = 363 nodules from 353 patients) between June 2013 and October 2017 at a single institution, with follow-up data collected until December 2019. Subgroup analysis was performed based on classification of repeat FNA cytology. Outcomes of GEC testing, clinical/sonographic surveillance of unresected nodules, and histopathologic diagnoses of thyroidectomies were compared between three testing approaches: (i) Reflex (MT sent on the basis of the initial Bethesda III/IV FNA), (ii) SemiRestrictive (MT sent if repeat FNA is Bethesda I-IV), and (iii) Restrictive (MT sent only if repeat FNA is Bethesda III/IV) testing approaches. Results: Restricting MT to nodules that remain Bethesda III/IV on repeat FNA would have missed 4 low-risk cancers and 3 noninvasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTP) (collectively 2% of the test population) but would have avoided diagnostic surgery for 42 benign nodules (12% of the test population). The Restrictive testing strategy was more specific (delta 0.126 confidence interval [CI 0.093 to 0.159] and 0.129 [CI 0.097 to 0.161], respectively) but less sensitive (delta -0.339 [CI -0.424 to -0.253] and -0.340 [CI -0.425 to -0.255], respectively) than the Reflex and SemiRestrictive approaches for detecting NIFTP or cancer. Conclusions: Repeat FNA cytology can guide the selection of cytologically indeterminate thyroid nodules that warrant MT. The Restrictive model of performing Afirma GEC only on nodules with two separate biopsies showing Bethesda III/IV cytology would reduce the rate of diagnostic surgery for histologically benign nodules while missing only rare low-risk tumors. Given the low but nontrivial risks of thyroidectomy, the higher specificity of the Restrictive testing approach disproportionately outweighs the potential harms.

Retrospective analysis of cancer-specific gene expression panel for thyroid fine needle aspiration specimens

BACKGROUND

While molecular testing is a promising strategy for preoperative assessment of cytologically indeterminate thyroid nodules, thyroid fine needle aspiration biopsy (FNA) presents unique challenges for molecular assays, including contaminating peripheral blood mononuclear cells (PBMC) and variable numbers of evaluable epithelial thyroid cells. Moreover, the newly recognized entity, noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), has added an additional challenge to the currently available molecular diagnostic platforms. New diagnostic tools are still needed to correctly distinguish benign and malignant thyroid nodules preoperatively.

METHODS

Twenty-two transcript splice variants from 12 genes we previously identified as discriminating benign from malignant thyroid nodules were characterized in 80 frozen thyroid tumors from 8 histological subtypes. Isoforms detectable in PBMC were excluded, and the 5 most discriminating isoforms were further validated by real-time quantitative PCR (qPCR) on intraoperative FNA samples from 59 malignant tumors, 55 benign nodules, and 23 NIFTP samples. The qPCR threshold cycle values for each transcript were normalized to the thyrocyte-specific thyroid peroxidase isoform 1 (TPO1) and z-transformed. Receiver operating characteristic (ROC) analyses of the composite transcript scores were used to evaluate classification of thyroid FNAs by the 5-gene isoform expression panel.

RESULTS

A molecular signature was developed by combining expression levels of specific isoforms of CDH3, FNDC4, HMGA2, KLK7, and PLAG1. FNAs containing at least 12-36 thyrocytes were sufficient for this assay. The 5-gene composite score achieved an area under the ROC curve (AUC) of 0.86 for distinguishing malignant from benign nodules, with a specificity of 91%, sensitivity of 75%, negative predictive value of 91%, and positive predictive value of 74%.

CONCLUSION

Our newly developed 5-gene isoform expression panel distinguishes benign from malignant thyroid tumors and, may help distinguish benign from malignant thyroid nodules in the context of the new NIFTP subtype.

Impact of Molecular Testing on the Management of Indeterminate Thyroid Nodules Among Western and Asian Countries: a Systematic Review and Meta-analysis

Molecular testing has a potential to improve the management of patients with indeterminate thyroid nodules considered for surgery. This study examined the influence of molecular tests on the treatment of indeterminate nodules, particularly the differences between Western and Asian countries. Electronic databases including PubMed and Web of Science were searched for relevant articles from 2010 to March 2019. We computed meta-analysis of proportion and their 95% confidence intervals (CIs) utilizing the random-effect model. We used independent samples t test to compare the resection rate (RR), rate of malignancy (ROM), rate of preoperative molecular testing (RMT), and rate of positive test (RP) between subgroups. We included a total of 34 studies with 7976 indeterminate nodules. The multigene panel testing methods were exclusively used in the USA. Compared with the non-molecular era, molecular testing was associated with a significantly increased ROM (47.9% versus 32.1%; p = 0.001). The ROM of indeterminate nodules in Asian institutes was significantly higher than that in Western countries (75.3% versus 36.6%; p < 0.001, respectively). Institutes employing single-gene tests achieved a higher ROM (59.8% versus 37.9%; p = 0.013). Molecular testing is a promising method to tailor the clinical management for indeterminate thyroid FNA. Certain differences in routine thyroid cytopathology practice among the West and the East are still present. The combination of molecular testing and active surveillance enhances the accuracy of case selection for surgery in Asian countries.

Molecular Profiling of Thyroid Nodules-Are These Findings Meaningful, or Merely Measurable?: A Review

Importance

Advances in genomic technologies have facilitated the development of sophisticated molecular diagnostic tests for thyroid nodules, in the hopes of better risk stratifying nodules with indeterminate cytopathologic diagnosis. It is unclear whether the widespread, or reflexive, use of these tests will improve outcomes for patients with thyroid nodules.

Observations

Thyroid nodules are a common and essentially normal finding. Even cytologically indeterminate thyroid nodules have a very low probability (approximately 1%) of representing clinically aggressive cancers and an even lower probability (approximately 0.1%) of representing lethal cancers. Therefore, most indeterminate thyroid nodules are low risk. Even if some will eventually require surgery, many can initially be kept under surveillance rather than requiring immediate surgery. Clinical and radiographic features can be helpful in risk stratifying these nodules. Molecular assays are marketed as tools to improve risk stratification for cytologically indeterminate thyroid nodules. However, the performance of these tests varies markedly across different practice settings, and the predictive value of these tests in real world practice may be lower than the numbers provided on laboratory reports. It is unclear whether these assays improve patient outcomes, such as survival or quality of life, or substantially reduce the number of thyroid surgeries performed.

Conclusions and Relevance

Because of variable performance, unclear benefit to patients, and questionable cost-effectiveness, clinical practice guidelines in the US and Europe currently do not recommend the universal, reflexive use of molecular assays for cytologically indeterminate thyroid nodules. These tests might offer value when used in selected scenarios, although this is not well understood. Future research should address whether the routine use of these molecular diagnostic tests leads to superior patient survival or quality-of-life outcomes compared with management based on clinical and radiographic criteria.

Complement C4-A and Plasminogen as Potential Biomarkers for Prediction of Papillary Thyroid Carcinoma

BACKGROUND

Early diagnosis and therapy of papillary thyroid carcinoma (PTC) is essential for reducing recurrence and improving the long-term survival. In this study, we aimed to investigate the proteome profile of plasma and screen unique proteins which could be used as a biomarker for predicting PTC.

METHODS

Serum samples were collected from 29 PTC patients and 29 nodular goiter (NG) patients. Five PTC serum samples and five NG serum samples were selected for proteome profiles by proteomics. Eight proteins in PTC and NG serum samples were selected for confirmation by enzyme-linked immunosorbent assay analysis. Receiver operating characteristic curves was used to evaluate the diagnostic value of potential biomarkers.

RESULTS

Complement C4-A (C4A) and plasminogen (PLG) were significantly lower in serum samples of PTC patients compared with NG patients. C4A was observed to have excellent diagnostic accuracy for PTC, with a sensitivity of 91.67% and specificity of 83.33%. The diagnostic value of PLG for PTC was demonstrated by a sensitivity at 87.50% and specificity at 75.00%. The AUC for C4A and PLG was 0.97 ± 0.02 and 0.89 ± 0.05.

CONCLUSION

C4A and PLG appeared to be excellent potential biomarkers for the prediction of PTC.

Thyroseq v3, Afirma GSC, and microRNA Panels Versus Previous Molecular Tests in the Preoperative Diagnosis of Indeterminate Thyroid Nodules: A Systematic Review and Meta-Analysis

BACKGROUND

Molecular tests are being used increasingly as an auxiliary diagnostic tool so as to avoid a diagnostic surgery approach for cytologically indeterminate thyroid nodules (ITNs). Previous test versions, Thyroseq v2 and Afirma Gene Expression Classifier (GEC), have proven shortcomings in malignancy detection performance.

OBJECTIVE

This study aimed to evaluate the diagnostic performance of the established Thyroseq v3, Afirma Gene Sequencing Classifier (GSC), and microRNA-based assays versus prior iterations in ITNs, in light of "rule-in" and "rule-out" concepts. It further analyzed the impact of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) reclassification and Bethesda cytological subtypes on the performance of molecular tests.

METHODS

Pubmed, Scopus, and Web of Science were the databases used for the present research, a process that lasted until September 2020. A random-effects bivariate model was used to estimate the summary sensitivity, specificity, positive (PLR) and negative likelihood ratios (NLR), and area under the curve (AUC) for each panel. The conducted sensitivity analyses addressed different Bethesda categories and NIFTP thresholds.

RESULTS

A total of 40 eligible studies were included with 7,831 ITNs from 7,565 patients. Thyroseq v3 showed the best overall performance (AUC 0.95; 95% confidence interval: 0.93-0.97), followed by Afirma GSC (AUC 0.90; 0.87-0.92) and Thyroseq v2 (AUC 0.88; 0.85-0.90). In terms of "rule-out" abilities Thyroseq v3 (NLR 0.02; 95%CI: 0.0-2.69) surpassed Afirma GEC (NLR 0.18; 95%CI: 0.10-0.33). Thyroseq v2 (PLR 3.5; 95%CI: 2.2-5.5) and Thyroseq v3 (PLR 2.8; 95%CI: 1.2-6.3) achieved superior "rule-in" properties compared to Afirma GSC (PLR 1.9; 95%CI: 1.3-2.8). Evidence for Thyroseq v3 seems to have higher quality, notwithstanding the paucity of studies. Both Afirma GEC and Thyroseq v2 performance have been affected by NIFTP reclassification. ThyGenNEXT/ThyraMIR and RosettaGX show prominent preliminary results.

CONCLUSION

The newly emerged tests, Thyroseq v3 and Afirma GSC, designed for a "rule-in" purpose, have been proved to outperform in abilities to rule out malignancy, thus surpassing previous tests no longer available, Thyroseq 2 and Afirma GEC. However, Thyroseq v2 still ranks as the best rule-in molecular test.

SYSTEMATIC REVIEW REGISTRATION

http://www.crd.york.ac.uk/PROSPERO, identifier CRD42020212531.

Molecular trait of follicular-patterned thyroid neoplasms defined by MALDI-imaging

In the field of thyroid neoplasms, the most interesting recent change regards the introduction of a new terminology for follicular-patterned thyroid tumors, named Noninvasive Thyroid Neoplasm with Papillary-like Nuclear Features (NIFTP). This pre-malignant tumor is considered to be the putative precursor of invasive carcinoma. However, given that several issues are still unresolved, the application of ancillary tools, based on omics-techniques, may improve the clinical management of these challenging cases. The present paper highlights the proteomic profiles of a series of NIFTPs submitted to Fine Needle Aspirations (FNAs) and analysed by MALDI-imaging in order to confirm the heterogeneous phenotype of nodules included in the present NIFTP terminology and to underline the necessity of more accurate biomarkers that can be used for their characterization. Ethical and economic implications in terms of healthcare costs, operative risks, morbidity, as well as the potential need for lifelong hormone replacement therapy, seem to be significant reasons to approach the characterization of NIFTPs using alternative tools such as MALDI-MSI.

Quantitative Analysis of Galectin-3 Expression in Benign and Malignant Thyroid Nodules

In this study, galectin-3 was analyzed as a potential marker for preoperative detection of malignant thyroid lesions. Galectin-3 expression was analyzed by quantitative real-time reverse transcription polymerase chain reaction (RT-PCR) in preoperative thyroid fine-needle aspirates from 245 patients with thyroid nodules. Out of 245 samples, 238 were adequate for analysis by RT-PCR. Galectin-3 was positive in 34 (89.5%) of 38 papillary carcinomas, 3 (89.5%) of 4 follicular carcinomas, 17 (53.1%) of 32 follicular adenomas, 2 (33.3%) of 6 Hurthle cell adenoma, 11 (28.2%) of 39 Hashimoto thyroiditis, and 69 (57.9%) of 119 nodular goiter samples. Galectin-3 showed specificity of 49.5%, sensitivity of 88.1%, positive predictive value of 27.2%, and negative predictive value of 95.1% as a marker for detection of malignant thyroid nodules. Owing to the relatively low positive predictive value due to the relatively high false positive rate, the clinical value of galectin-3 analyzed by quantitative real-time RT-PCR as a marker for preoperative detection of malignant thyroid lesions is limited.

The American Association of Endocrine Surgeons Guidelines for the Definitive Surgical Management of Thyroid Disease in Adults

OBJECTIVE

To develop evidence-based recommendations for safe, effective, and appropriate thyroidectomy.

BACKGROUND

Surgical management of thyroid disease has evolved considerably over several decades leading to variability in rendered care. Over 100,000 thyroid operations are performed annually in the US.

METHODS

The medical literature from 1/1/1985 to 11/9/2018 was reviewed by a panel of 19 experts in thyroid disorders representing multiple disciplines. The authors used the best available evidence to construct surgical management recommendations. Levels of evidence were determined using the American College of Physicians grading system, and management recommendations were discussed to consensus. Members of the American Association of Endocrine Surgeons reviewed and commented on preliminary drafts of the content.

RESULTS

These clinical guidelines analyze the indications for thyroidectomy as well as its definitions, technique, morbidity, and outcomes. Specific topics include Pathogenesis and Epidemiology, Initial Evaluation, Imaging, Fine Needle Aspiration Biopsy Diagnosis, Molecular Testing, Indications, Extent and Outcomes of Surgery, Preoperative Care, Initial Thyroidectomy, Perioperative Tissue Diagnosis, Nodal Dissection, Concurrent Parathyroidectomy, Hyperthyroid Conditions, Goiter, Adjuncts and Approaches to Thyroidectomy, Laryngology, Familial Thyroid Cancer, Postoperative Care and Complications, Cancer Management, and Reoperation.

CONCLUSIONS

Evidence-based guidelines were created to assist clinicians in the optimal surgical management of thyroid disease.

High-risk and intermediate-high-risk results from the ThyroSeq v2 and v3 thyroid genomic classifier are associated with neoplasia: Independent performance assessment at an academic institution

BACKGROUND

The ThyroSeq panel tests for genetic alterations to risk-stratify cytologically indeterminate nodules. The authors assessed the test performance of the tests, including the latest version (v3), at an academic center.

METHODS

Results from ThyroSeq testing (v2 and v3) were reviewed over 2 years, and patient demographics, cytology diagnoses, results of ThyroSeq testing, and histopathologic diagnoses on resection (if available) were collected.

RESULTS

One hundred eighty-five nodules were tested from 178 patients, including 94 nodules tested with v2 and 91 nodules tested with v3. Overall, 28 of 185 nodules (15%) yielded a high-risk or intermediate-high-risk mutation (HRM). Of the patients with these nodules, 19 of 25 (76%) had neoplastic nodules, and 11 of 25 (44%) had a malignancy or a noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). Only 16 of 147 nodules (11%) that were negative or had low-risk genetic alterations underwent resection, with 1 false-negative result (a papillary thyroid carcinoma tested with v2). No false-negative results were identified with v3. Two nodules had TP53 mutations identified, both of which were benign on resection. Nodules with HRM that were tested with v2 and v3 had a positive predictive value (PPV) for malignancy of 57% and 39%, respectively, and a PPV for neoplasm of 86% and 72%, respectively. The negative predictive values for v2 and v3 were 92% and 100%, respectively.

CONCLUSIONS

The PPV of an HRM result on ThyroSeq v3 was low for malignancy or NIFTP, and the PPV for neoplasm was higher. RAS-type mutations were the most commonly identified in both benign and malignant nodules. Thyroseq v3 had a lower PPV for both malignancy/NIFTP and neoplasm than v2 but did not produce any false-negative results.

EIF1AX c.338-2A>T splice site mutation in a patient with trabecular adenoma and cytological indeterminate lesion

The EIF1AX gene mutations have been recently associated with papillary thyroid carcinoma and anaplastic thyroid cancer. According with these reports, the gene as been considered as a drive gene for thyroid cancer development. However, the occurrence of these alterations in benign thyroid lesions is not known and is still under investigation. Some authors have already reported the presence of EIF1AX variants in follicular adenomas and hyperplastic nodules. Here, we describe for the first time a case of a man with the EIF1AX c.338-2A>T splice site mutation in an indeterminate FNA lesion with trabecular adenoma at final histology in the absence of other pathogenetic mutations, demonstrating that further studies are required to better understand EIF1AX role in the tumorigenesis of thyroid carcinoma.

Long-Term Outcomes of Thyroid Nodule AFIRMA GEC Testing and Literature Review: An Institutional Experience

Objective

To assess outcomes of thyroid nodules analyzed with the AFIRMA gene expression classifier (GEC) and to perform a comprehensive literature review.

Study Design

Retrospective analysis of patients with thyroid nodules who underwent AFIRMA GEC testing at our institution.

Settings

A tertiary care academic institution.

Subjects and Methods

We collected clinical outcomes for 416 thyroid nodules that were analyzed with AFIRMA GEC between 2011 and 2015, including long-term follow-up through 2019. We performed a comprehensive literature review.

Results

The resection rate for nodules with “suspicious” GEC results was 85% with a positive predictive value of 37%. The resection rate for nodules with “benign” GEC results was 24% with a negative predictive value of 90%. The prevalence of thyroid malignancy in patients with thyroid nodules with indeterminate cytology at our institution during this timeframe was 41%, thus lowering our negative predictive value. Mean follow-up duration for unresected nodules was 27.8 months. Our resection rates for nodules with “benign” GEC were among the highest reported in the literature.

Conclusions

Molecular marker testing of thyroid nodules with indeterminate cytology can aid in the surgical decision making by obviating the need for diagnostic surgery and/or guiding extent of resection. Patients with other indications for surgery may not benefit from such costly testing.

Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features (NIFTP): An Update

Based on evidence accumulated over the past three decades showing that noninvasive encapsulated follicular variant of papillary thyroid carcinoma has an indolent clinical behavior and a RAS-like molecular profile similar to follicular adenoma, the Endocrine Pathology Society working group in 2016 proposed to rename this entity as "noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP)" in order to eliminate the term "carcinoma" from the diagnosis. It is a major evidence-based attempt initiated by an international group of endocrine pathologists to tackle the epidemic of thyroid cancer overdiagnosis and overtreatment. However, its creation and continuous existence are not without controversies. NIFTP has sparked a wave of follow up studies aiming to decipher the exact nature of this new entity. In this review, we summarize the rationale, diagnostic criteria, controversies and subsequent changes to the NIFTP concept, and their impact on patient care and pathology practice.

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features: a problematic entity

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is a borderline thyroid tumour formerly known as noninvasive encapsulated follicular variant of papillary thyroid carcinoma. The prevalence of NIFTP is estimated at 4.4-9.1% of all papillary thyroid carcinomas worldwide; however, the rate of occurrence of NIFTP is eight times lower in Asian countries than in Western Europe and America. At the molecular level, NIFTP is characterised by the lack of BRAF V600E and BRAF V600E-like mutations or other high-risk mutations (TERT, TP53), and a high rate of RAS mutations, which is similar to other follicular-pattern thyroid tumours. The diagnosis of NIFTP can only be made after histological examination of the entire tumour removed during surgery, and is based on strictly defined inclusion and exclusion criteria. Although the diagnosis is postoperative, the combination of certain findings of preoperative tests including ultrasonography, cytology, and molecular testing may raise suspicion of NIFTP. These tumours can be effectively treated by lobectomy, although total thyroidectomy remains an option for some patients. Radioactive iodine and thyroid stimulating hormone suppression therapy are not required. NIFTP has an extremely good prognosis, even when treated conservatively with lobectomy alone. Nevertheless, it cannot be considered as a benign lesion. The risk of adverse outcomes, including lymph node and distant metastases, is low but not negligible.

Thyroid nodules: diagnostic evaluation based on thyroid cancer risk assessment

Thyroid nodules are extremely common and can be detected by sensitive imaging in more than 60% of the general population. They are often identified in patients without symptoms who are undergoing evaluation for other medical complaints. Indiscriminate evaluation of thyroid nodules with thyroid biopsy could cause a harmful epidemic of diagnoses of thyroid cancer, but inadequate selection of thyroid nodules for biopsy can lead to missed diagnoses of clinically relevant thyroid cancer. Recent clinical guidelines advocate a more conservative approach in the evaluation of thyroid nodules based on risk assessment for thyroid cancer, as determined by clinical and ultrasound features to guide the need for biopsy. Moreover, newer evidence suggests that for patients with indeterminate thyroid biopsy results, a combined assessment including the initial ultrasound risk stratification or other ancillary testing (molecular markers, second opinion on thyroid cytology) can further clarify the risk of thyroid cancer and the management strategies. This review summarizes the clinical importance of adequate evaluation of thyroid nodules, focuses on the clinical evidence for diagnostic tests that can clarify the risk of thyroid cancer, and highlights the importance of considering the patient's values and preferences when deciding on management strategies in the setting of uncertainty about the risk of thyroid cancer.

Utility of Routine Frozen Section of Thyroid Nodules Classified as Follicular Neoplasm

OBJECTIVES

To evaluate the diagnostic performance of frozen section in thyroid nodules classified as follicular neoplasm.

METHODS

A diagnostic test meta-analysis was designed. Studies that assessed frozen section in patients with thyroid nodules and a fine-needle aspiration biopsy result of Bethesda IV were selected. The outcomes measured were the number of false- and true-positive and -negative results. We used the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) instrument for methodological quality assessment and a bivariate mixed-effects regression framework and a likelihood-based estimation of the exact binomial approach.

RESULTS

Forty-six studies from 1991 to 2018 were included. Most studies had moderate methodological quality. The overall sensitivity and specificity were 43% (95% confidence internal [CI], 0.34-0.53) and 100% (95% CI, 0.99-1.00), respectively. The hierarchic summary receiver operating characteristic curve showed an area under the curve of 0.91 (95% CI, 0.80-0.97).

CONCLUSIONS

Frozen section demonstrates moderate diagnostic performance in patients with follicular neoplasm, and its utility for making intraoperative decisions is limited. Its routine use should be discouraged.

Differences in surgical resection rate and risk of malignancy in thyroid cytopathology practice between Western and Asian countries: A systematic review and meta-analysis

There is increasing evidence showing that clinicians employ different management strategies in their use of The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). In this meta-analysis, we investigated the differences in diagnosis frequency, resection rate (RR), and risk of malignancy (ROM) between Western (ie, American and European) and Asian cytopathology practices. We searched PubMed and Web of Science from January 2010 to January 2019. Proportion and 95% CIs were calculated using a random-effect model. We used independent sample t tests to compare frequencies, RR, and ROM between Western and Asian practices. We analyzed a total of 38 studies with 145,066 fine-needle aspirations. Compared with Asian practice, Western series had a significantly lower ROM in most of TBSRTC categories, whereas the RR was not statistically different. Focusing on indeterminate nodules, the RR in Western series was significantly higher (51.3% vs 37.6%; P = .048), whereas the ROM was significantly lower (25.4% vs 41.9%; P = .002) compared with those in Asian series. The addition of Asian cohorts increased ROM for most of diagnostic categories compared with the original TBSRTC. In conclusion, this study demonstrates a difference in Western and Asian thyroid cytology practice, especially regarding the indeterminate categories. Lower RR and higher ROM suggest that Asian clinicians adopt a more conservative approach, whereas immediate diagnostic surgery is favored in Western practice for indeterminate nodules. The addition of Asian series into a meta-analysis of TBSRTC altered ROM for several categories, which should be considered in future revisions of TBSRTC.

The impact of non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) on the diagnosis of thyroid nodules

More than 70 years ago, Prof. Pierre Masson, a renowned French-Canadian pathologist (1880-1959), advised us that "No classification is more difficult to establish than that of thyroid carcinomas…Of all cancers, they teach, perhaps, the greatest lessons of humility to histopathologists." Almost 70 years later, the recent evidence-based reclassification of the non-invasive encapsulated follicular variant of papillary thyroid carcinoma (FVPTC) as non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), has demonstrated that this problematic is still ongoing. For about 30 years, it was wrongly assumed that the encapsulated FVPTC behaved and spread like its classical counterpart and, therefore, that it should be treated likewise. As such, the renaming of a malignant entity as a nonmalignant (albeit not benign) neoplasm has contributed to optimizing patient care by deescalating treatment and follow-up for an indolent neoplasm, decreasing medical expense and complications possibly caused by further treatment including radioactive iodine, and reassuring patients with this diagnosis. At the same time, NIFTP has significant implications not only for the practice of thyroid cytopathology but also for surgical pathology and for molecular tests, creating significant new challenges. NIFTP has rigorous histopathologic diagnostic criteria, including papillary-like nuclear features, and submission of the entire tumor capsule and content is required to exclude both invasion and presence of papillary structures. Cytologically, because of the morphological overlap with other follicular neoplasms and with papillary thyroid carcinoma (PTC), most NIFTP are diagnosed into one of the indeterminate Bethesda categories (III-V) and can be adequately triaged for surgery. From a molecular view, NIFTP are most often characterized by RAS-type mutations, similar to other follicular-patterned lesions, and molecular testing can be helpful to suggest NIFTP preoperatively. In this review, we focus on the impact of NIFTP on the diagnosis of thyroid nodules.

Hürthle cell lesions on thyroid fine needle aspiration cytology: Molecular and histologic correlation

BACKGROUND

Hürthle cell lesions often pose diagnostic challenges, despite their common occurrence on thyroid fine-needle aspiration cytology (FNAC). The associated molecular alterations are also not well understood. Therefore, our study aimed to delineate the molecular profile of Hürthle cell lesions classified as Bethesda Categories III or IV (atypia of undetermined significance (AUS) or suspicious for follicular neoplasm (SFN)) on FNAC and to correlate this molecular profile with surgical resection findings.

METHODS

This study consisted of 188 Hürthle cell lesions with indeterminate cytology and ThyroSeq® v2/v3 molecular testing results. Surgical follow-up was available for 33 cases.

RESULTS

The majority of indeterminate Hürthle cell lesions had negative ThyroSeq® results (61%) and were benign on available surgical follow-up. The most prevalent mutations involved the RAS gene (21%), which were associated with benign lesions, non-invasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTP), and malignancy. The remaining mutations involved less than 18% of the cases, including PAX8/PPARG (3.7%), TSHR (3.7%), EIF1AX (2.7%), MET (2.1%), PTEN (1.6%), clonal copy number alteration (1.6%), TERT (1.1%), and 0.5% each of GNAS, PIK3CA, and TP53 mutations. On follow-up, 45% were benign, 24% were NIFTP, and 30% were malignant. The malignant cases had different molecular alterations.

CONCLUSION

No single molecular alteration defines cytologically indeterminate Hürthle cell lesions; the majority of cases have low-risk or no molecular alterations and are benign on follow-up. These findings suggest that molecular testing may be useful, but is not definitive, in determining which cases may be managed conservatively; additional studies are needed to fully determine the negative predictive value in ruling out malignancy.

USING THE ATA AND ACR TI-RADS SONOGRAPHIC CLASSIFICATIONS AS ADJUNCTIVE PREDICTORS OF MALIGNANCY FOR INDETERMINATE THYROID NODULES

Objective: Thyroid nodules with indeterminate cytology pose management challenges in clinical practice. The aim of this study was to determine the efficacy of ultrasound features in navigating clinical decision making in thyroid nodules with indeterminate cytology. Methods: We retrospectively reviewed ultrasound imaging from 186 adult patients with thyroid nodules and indeterminate cytology who underwent thyroidectomy at a quaternary hospital from 2010-2017. All nodules were classified based on the American Thyroid Association (ATA) and 2017 American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS). Nodules were included if good quality pre-operative ultrasound imaging and surgical pathology were available. Results: A total of 202 thyroid nodules were included. The median age was 57 years; 82.8% were female. Risk of malignancy (ROM) in resected nodules with Bethesda 3 and 4 cytology was 19.4% and 30.3%, respectively. ATA high-suspicious and TI-RADS 5 nodules had high ROM, 100% in both systems for Bethesda 3 nodules; 66.7% and 50.0%, respectively, for Bethesda 4 nodules. For ATA very-low suspicious/TI-RADS 1 and 2, ROM was 0%. ROM in ATA low-suspicious/TI-RADS 3 nodules with Bethesda 3 cytology was lower (15.2% and 16.0%, respectively) than Bethesda 4 cytology (33.8% and 34.3%, respectively). ATA intermediate-suspicious/TI-RADS 4 nodules with Bethesda 4 cytology had a lower ROM (11.1% and 18.2%, respectively) than Bethesda 3 cytology (28.6 % and 31.6%, respectively). Conclusion: Using either the ATA or the TI-RADS system to risk-stratify nodules with indeterminate cytology may help clinicians plan better for additional diagnostic testing and treatment. Abbreviations: ACR = American College of Radiology; ATA = American Thyroid Association; AUS = atypia of undetermined significance; FLUS = follicular lesion of undetermined significance; FN = follicular neoplasm; PPV = positive predictive value; ROM = risk of malignancy; SFN = suspicious for follicular neoplasm; TI-RADS = Thyroid Imaging Reporting and Data System.

Non-invasive follicular thyroid neoplasm with papillary-like nuclearfeatures (NIFTP): a review and update

BACKGROUND

The nomenclature "Non-invasive Follicular Neoplasm with Papillary-like Nuclear Features (NIFTP)" was introduced in 2016. While NIFTP differs from classic papillary thyroid carcinoma (PTC) in imaging, cytomorphology, histology, molecular profile, treatment, follow up, outcome, and behavior, it largely overlaps with follicular variant of PTC at imaging and cytomorphology. Herein, we review the literature for better understanding NIFTP, and its impact on patient care.

METHODS

The English literature was thoroughly evaluated with the key word of "Noninvasive follicular neoplasm with papillary-like nuclear features (NIFTP)".

OBSERVATIONS

NIFTP presents as a thyroid nodule. On imaging, it is a round-to-oval, well circumscribed mass with solid internal content. Aspirated material shows a microfollicular pattern with focal nuclear features of PTC mostly reported in categories 3-5 of the Bethesda System for Reporting Thyroid Cytology (TBRSTC). NIFTP has decreased risk of malignancy in TBRSTC categories 3-6. Histologic examination of NIFTP reveals an encapsulated neoplasm with follicular pattern and nuclear features of PTC with no capsular or vascular invasion. No papillary structure, atypia, or mitosis is present. In contrast to PTC, only 4% of NIFTP cases harbor a BRAF mutation. Because NIFTP carries an excellent prognosis and indolent behavior, the tumor behavior was changed from malignant to a neoplasm with tumor with extremely indolent behavior. The recommended treatment is lobectomy with no further ablation therapy. Until better understanding of NIFTP, patient's follow up should be occasionally performed by neck ultrasonography and serum thyroglobulin measurement.

CONCLUSION

NIFTP carries an excellent prognosis. It is critical for both clinicians and patients to be aware of extremely indolent behavior of NIFTP in order to prevent unnecessary, aggressive treatment.

Incidence of noninvasive follicular thyroid neoplasm with papillary-like nuclear features and change in risk of malignancy for "The Bethesda System for Reporting Thyroid Cytology"

INTRODUCTION

The second edition of The Bethesda System for Reporting Thyroid Cytopathology has incorporated the recent change in nomenclature, noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), with an anticipated change in the risk of malignancy (ROM). We examined our institutional experience in the incidence of NIFTP and the change in the ROM in The Bethesda System for Reporting Thyroid Cytopathology.

MATERIALS AND METHODS

A computerized search was performed from January 2013 to August 2017 for all thyroid fine needle aspirations (FNAs), the corresponding surgical resection specimens, and clinical follow-up data. All thyroid specimens reported as follicular variant of papillary thyroid carcinoma were reviewed and reclassified, and all NIFTP diagnoses from April 2016 to August 2017 were identified. The ROM for each category was calculated before and after the change and analyzed for significance.

RESULTS

A total of 4500 thyroid FNA cases were collected. Of these, 479 cases had surgical resection specimens available and 36 cases had been diagnosed as NIFTP. Of these, 22 had been previously diagnosed as FVPT. Of 27 cases of NIFTP, 14 and 13 were atypia of undetermined significance/follicular lesion of undetermined significance and follicular neoplasm/suspicious for follicular neoplasm, respectively. A reduction in the ROM was observed in these 2 categories (P = 0.03 and P = 0.04, respectively).

CONCLUSIONS

In our institution, NIFTP has accounted for 13% of all malignant thyroid neoplasms since the change in nomenclature. Although the ROM was decreased in the affected categories, with absolute statistically significant decreases in ROM of 15% and 16.2% for category III and IV, respectively, the overall ROM change was marginal.

Role of Ancillary Techniques in Thyroid Cytology Specimens

Ancillary molecular testing has emerged as a promising way to refine the preoperative risk stratification of thyroid nodules with indeterminate fine needle aspiration (FNA) biopsy results. Commercially available molecular tests for thyroid FNAs include those that analyze samples for mutations and gene fusions, gene expression alterations, microRNA expression alterations, chromosomal copy number alterations, or a combination thereof. This review summarizes the performance characteristics of the most current iterations of three tests currently marketed for cytologically indeterminate thyroid nodules: ThyroSeq v3, ThyGeNEXT/ThyraMIR, and Afirma Gene Sequencing Classifier.

Update on: proteome analysis in thyroid pathology - part II: overview of technical and clinical enhancement of proteomic investigation of the thyroid lesions

INTRODUCTION

An accurate diagnostic classification of thyroid lesions remains an important clinical aspect that needs to be addressed in order to avoid 'diagnostic' thyroidectomies. Among the several 'omics' techniques, proteomics is playing a pivotal role in the search for diagnostic markers. In recent years, different approaches have been used, taking advantage of the technical improvements related to mass spectrometry that have occurred. Areas covered: The review provides an update of the recent findings in diagnostic classification, in genetic definition and in the investigation of thyroid lesions based on different proteomics approaches and on different type of specimens: cytological, surgical and biofluid samples. A brief section will discuss how these findings can be integrated with those obtained by metabolomics investigations. Expert commentary: Among the several proteomics approaches able to deepen our knowledge of the molecular alterations of the different thyroid lesions, MALDI-MSI is strongly emerging above all. In fact, MS-imaging has also been demonstrated to be capable of distinguishing thyroid lesions, based on their different molecular signatures, using cytological specimens. The possibility to use the material obtained by the fine needle aspiration makes MALDI-MSI a highly promising technology that could be implemented into the clinical and pathological units.

Outcomes of Bethesda categories III and IV thyroid nodules over 5 years and performance of the Afirma gene expression classifier: A single-institution study

OBJECTIVE

The second edition Bethesda System for Reporting Thyroid Cytology estimates 6%-18% malignancy rate of category III (B3) and 10%-40% for category IV (B4) nodules; however, reported malignancy rates have considerable variability among institutions. Use of molecular classifiers (including Afirma Gene Expression Classifier, GEC) can be utilized in management of thyroid nodules. Our objective was to analyse malignancy rates of B3 and B4 nodules and determine clinical outcomes of GEC Benign nodules.

METHODS

A retrospective analysis of 2019 thyroid FNAs was performed at the University of Colorado from 2011 to 2015, including molecular, surgical and clinical follow-up.

RESULTS

Of 2019 FNAs analysed, 231 (11.4%) were diagnosed as B3 and 80 (4.0%) as B4. GEC was obtained in 54.1% of B3 cases, with nearly half (48.8%) having a Benign result. Surgery was performed in 40.7% B3 cases with a 24.5% malignancy rate, ranging 8%-38% by year. In the B4 group, 52.5% underwent molecular testing with 28.6% as GEC Benign. About 68.8% of B4 cases underwent surgery with a 20% malignancy rate, ranging 0%-42% by year. Seventy-three GEC Benign cases were reviewed: 5 (6.8%) underwent surgery, with none demonstrating malignancy in the target nodule. Size remained stable for most GEC Benign nodules: 75.9% (B3) and 71.4% (B4) with no malignancy on repeat FNA.

CONCLUSIONS

Our 5-year review demonstrated that malignancy rates of B3 and B4 nodules showed year-to-year variability. We suggest that clinicians use a multi-year average of their institution's malignancy rates to optimally manage patients. Follow-up for GEC Benign cases thus far supports their indolent nature.