A Systematic Review of the Methods of Diagnostic Accuracy Studies of the Afirma Gene Expression Classifier

Assessment of the risk of malignancy in Bethesda III thyroid nodules: a comprehensive review

The increasing prevalence of thyroid cancer emphasizes the need for a thorough assessment of risk of malignancy in Bethesda III nodules. Various methods ranging commercial platforms of molecular genetic testing (including Afirma® GEC, Afirma® GSC, ThyroSeq® V3, RosettaGX®, ThyGeNEXT®/ThyraMIR®, ThyroidPRINT®) to radionuclide scans and ultrasonography have been investigated to provide a more nuanced comprehension of risk estimation. The integration of molecular studies and imaging techniques into clinical practice may provide clinicians with improved and personalized risk assessment. This integrated approach we feel may enable clinicians to carefully tailor interventions, thereby minimizing the likelihood of unnecessary thyroid surgeries and overall crafting the optimal treatment. By aligning with the evolving landscape of personalized healthcare, this comprehensive strategy ensures a patient-centric approach to thyroid nodule and thyroid cancer management.

Single BRAFV600E mutation is not associated with aggressive biological behavior in adolescent and pediatric papillary thyroid carcinoma

BACKGROUND

Papillary thyroid carcinoma is more likely to show aggressive biological behaviors in the majority of pediatric patients than in adult patients. The aim of this study was to investigate the mutation rate of the BRAFV600E gene in adolescents and children with papillary thyroid carcinoma and to analyze the association between BRAFV600E gene mutation and tumor-aggressive pathological factors.

METHODS

A total of 42 pediatric patients with papillary thyroid carcinoma who underwent thyroid surgery from 2017 to 2022 were studied retrospectively. Whether the BRAFV600E gene mutation in papillary thyroid carcinoma was related to aggressive biological behavior was analyzed.

RESULTS

Among the 42 pediatric patients with papillary thyroid carcinoma, the median patient age was 15.71 ± 2.51 years (mean ± SD) and the median tumor diameter was 24.95 ± 12.29 mm (mean ± SD). Among all enrolled patients, the mutation rate of the BRAFV600E gene was 54.76% (23 of 42). There were 33 patients with classic papillary thyroid carcinoma, and 22 (66.67%) with classic subtypes were BRAFV600E positive. The BRAFV600E mutation was associated with lower distant metastasis (p = .013) and less Hashimoto's thyroiditis (p = .006). There was no significant difference in clinicopathological factors such as sex, age, tumor size, capsular invasion, multifocality, hypothyroidism, recurrence, lymph node metastasis, and extrathyroidal extension.

CONCLUSIONS

The BRAFV600E mutation is not uncommon in pediatric papillary thyroid carcinoma but is not significantly associated with aggressive biological behavior. It is not possible to determine whether to adopt more active diagnosis and treatment measures on the basis of the mutation of a single BRAFV600E gene.

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.

Testing of mutations on thyroid nodules with indeterminate cytology: A prospective study of 112 patients in Argentina

BACKGROUND

The study of genetic mutations in thyroid nodules makes it possible to improve the preoperative diagnosis of and reduce unnecessary surgeries on benign nodules. In this study, we analysed the impact of implementing a 7-gene mutation panel that enables mutations to be detected in BRAF and RAS (H/N/K) and the gene fusions PAX8/PPARG, RET/PTC1 and RET/PTC2, in a population in northern Argentina.

METHODS

We performed a prospective analysis of 112 fine needle aspirations diagnosed as having indeterminate cytology according to the Bethesda classification system. These include the Bethesda III or atypia of unknown significance/follicular lesion of unknown significance and Bethesda IV or follicular neoplasm/suspicious for follicular neoplasm categories. The mutations of the 7-gene panel were analysed and this information was linked to the available histology and ultrasound monitoring.

RESULTS

The BRAF V600E and RET/PTC1 mutations were associated with carcinoma in 100% of cases (n = 8), whereas only 37.5% (n = 3) of the nodules with RAS and 17% (n = 1) with PAX8/PPARG mutations were associated with carcinoma. From the histological diagnosis and ultrasound monitoring of patients, we can estimate that this panel has a sensitivity of 86% in detecting malignant carcinoma, a specificity of 77%, a positive predictive value (PPV) of 54% and a negative predictive value (NPV) of 94%. In this study, it was possible to reduce the number of surgeries by 48% in the patients analysed.

CONCLUSION

The implementation of the mutation panel allowed the appropriate surgical strategy to be selected for each patient, the number of two-step surgeries to be reduced, and active follow-up to be established in low-risk patients.

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.

Testing of mutations on thyroid nodules with indeterminate cytology: A prospective study of 112 patients in Argentina

BACKGROUND

The study of genetic mutations in thyroid nodules makes it possible to improve the preoperative diagnosis of and reduce unnecessary surgeries on benign nodules. In this study, we analysed the impact of implementing a 7-gene mutation panel that enables mutations to be detected in BRAF and RAS (H/N/K) and the gene fusions PAX8/PPARG, RET/PTC1 and RET/PTC2, in a population in northern Argentina.

METHOD

We performed a prospective analysis of 112 fine needle aspirations diagnosed as having indeterminate cytology according to the Bethesda classification system. These include the Bethesda III or atypia of unknown significance/follicular lesion of unknown significance and Bethesda IV or follicular neoplasm/suspicious for follicular neoplasm categories. The mutations of the 7-gene panel were analysed and this information was linked to the available histology and ultrasound monitoring.

RESULTS

The BRAF V600E and RET/PTC1 mutations were associated with carcinoma in 100% of cases (n=8), whereas only 37.5% (n=3) of the nodules with RAS and 17% (n=1) with PAX8/PPARG mutations were associated with carcinoma. From the histological diagnosis and ultrasound monitoring of patients, we can estimate that this panel has a sensitivity of 86% in detecting malignant carcinoma, a specificity of 77%, a positive predictive value (PPV) of 54% and a negative predictive value (NPV) of 94%. In this study, it was possible to reduce the number of surgeries by 48% in the patients analysed.

CONCLUSION

The implementation of the mutation panel allowed the appropriate surgical strategy to be selected for each patient, the number of two-step surgeries to be reduced, and active follow-up to be established in low-risk patients.

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.

American Thyroid Association Sonographic Risk and Afirma Gene Expression Classifier Alone and in Combination for the Diagnosis of Thyroid Nodules with Bethesda Category III Cytology

Background: The Afirma gene expression classifier (GEC) has been used to aid in the diagnosis and management of thyroid nodules having Bethesda category III fine-needle aspiration cytologic diagnosis (B3 nodules). The American Thyroid Association sonographic risk stratification system for thyroid nodules (ATA-US) may stratify B3 nodules and aid in the decision to order a molecular test. The aim of this study was to assess the association between ATA-US and GEC as well as to determine their individual and combined diagnostic performances when applied to B3 nodules. Methods: A retrospective single-center study included B3 nodules that had undergone evaluation by GEC. Each ultrasound was reviewed by three radiologists, and nodules were classified using the 2015 ATA sonographic risk categories. Nodules were determined to be benign or malignant based on surgical pathology or minimum 11 months of follow-up. Positive predictive values (PPV) and negative predictive values (NPV) were calculated for GEC, ATA-US, and GEC across all ATA-US categories. Results: One hundred twenty-six B3 nodules with GEC results were included and deemed benign or malignant based on final pathology or follow-up. Prevalence of malignancy was 32%. The rate of malignancy was similar in the ATA-US high suspicion (HS) and intermediate suspicion (IS) categories at 42% and 38%, respectively; and lower in nodules with low suspicion sonography (LS) and very low suspicion sonography (VLS) at 23% and 11%, respectively. The PPV and NPV of ATA-US was calculated by designating HS or IS sonography as a "positive" test and the lower risk categories as "negative." ATA-US had a PPV of 40% and NPV of 79%. The GEC PPV was 40% and NPV was 83%. The PPV of GEC was 50% in nodules with HS or IS ATA-US and lower at 28% and 20%, respectively, in LS and VLS nodules. The NPV of GEC was 80% in HS, 77% in IS, 84% in LS, and 100% in VLS sonography categories. Conclusions: In B3 nodules, ATA-US and GEC have similar diagnostic performance. The PPV of GEC varies across ATA-US categories, while the NPV remains similar. These data support the need for future prospective studies.

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.

Comparison of Postmarketing Findings vs the Initial Clinical Validation Findings of a Thyroid Nodule Gene Expression Classifier: A Systematic Review and Meta-analysis

Importance

In the United States, the most used molecular test for the evaluation of cytologically indeterminate thyroid nodules is the Afirma gene expression classifier (GEC).

Objective

To evaluate the GEC's diagnostic performance through a novel approach to assess whether the findings of the initial validation study are consistent with the results of postmarketing studies.

Data Sources

PubMed was systematically searched from inception through October 26, 2017, using the terms gene expression classifier or Afirma or GEC and thyroid.

Study Selection

Studies included were those in which the GEC diagnostic performance could be calculated on consecutively resected cytologically indeterminate thyroid nodules.

Data Extraction and Synthesis

Two observers independently assessed study eligibility and risk of bias using the quality assessment tool for observational cohort and cross-sectional studies of the National Heart, Lung, and Blood Institute. Summary data were extracted by a reviewer and reviewed independently by another. Study authors were contacted if missing data were needed. Data were pooled using a random-effects model. PRISMA and MOOSE guidelines were followed.

Main Outcomes and Measures

Evaluation of the linear correlation between the benign call rate (BCR) and the positive predictive value (PPV).

Results

Of the 137 retrieved titles, 19 (13.9%) were included, comprising a total of 2568 thyroid nodules. Based on a simulation using the sensitivity and specificity reported in the initial validation study, the observed BCR and PPV values in postmarketing studies would have to be explained by different underlying prevalence rates of cancer (15% vs 30%), which is an impossible event. Furthermore, the overall correlation between BCR and PPV for independent studies fell outside the PPV 95% CI of the initial validation study (95% CI, 0.17-0.32) at the BCR of pooled independent studies (0.45) and was just at the limit of the BCR 95% CI of the initial validation study (95% CI, 0.32-0.45) at the PPV of pooled independent studies (0.45). The diagnostic performance was statistically significantly better for atypia or follicular lesions of undetermined significance (diagnostic odds ratio [DOR], 5.67; 95% CI, 4.23-7.60) compared with follicular neoplasms (DOR, 2.24; 95% CI, 1.45-3.47).

Conclusions and Relevance

The findings suggest that the initial validation study cohort was not representative of the populations in whom the GEC has been used, calling into question its reported diagnostic performance, including its negative predictive value.

The Diagnostic Performance of Afirma Gene Expression Classifier for the Indeterminate Thyroid Nodules: A Meta-Analysis

Background

Approximately 15 to 30% of thyroid nodules evaluated by fine-needle aspiration (FNA) were classified as indeterminate; the accurate diagnostic molecular tests of these nodules remain a challenge. We aimed to evaluate the diagnostic performance of Afirma gene expression classifier (GEC) for the indeterminate thyroid nodules (ITNs).

Methods

Studies published from January 2005 to December 2018 were systematically reviewed. The gold reference standard relied on the histopathologic results diagnosis from thyroidectomy surgical specimens. MetaDisc software was used to investigate the pooled sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV), diagnostic odds ratio (DOR), and summary receiver operating characteristic (SROC) curves.

Results

A total of 18 studies involving 5290 patients with 3290 cases of ITNs were included. Collected data revealed that the pooled sensitivity of GEC was 95.5% (95% CI 93.3%–97.0%, p < 0.001), the specificity was 22.1% (95% CI 19.4%-24.9%, p < 0.001), the NPV was 88.2% (95% CI 0.833–0.921, p < 0.001), the PPV was 44.3% (95% CI 0.416–0.471, p < 0.001), and the DOR was 5.25 (95% CI 3.42–8.04, p= 0.855).

Conclusion

The GEC has quite high sensitivity of 95.5% but low specificity of 22.1%. The high sensitivity makes it probable to rule out malignant nodules. Thus, over half of nodules with GEC-suspicious results still require further validation like molecular markers, diagnostic surgery, or long follow-up, which limits its use in future clinical practice.

Decision Making in Indeterminate Thyroid Nodules and the Role of Molecular Testing

Cytologically indeterminate thyroid nodules are associated with a broad range (5%-75%) of malignant risk and accurately informing definitive management poses a challenge. Advancements in molecular testing of fine-needle aspiration biopsies have improved preoperative diagnostic accuracy and prognostication. For indeterminate nodules, such testing ideally will reduce the need for surgery for benign nodules and potentially guide appropriate extent of initial surgery for malignancy.

Extending expressed RNA genomics from surgical decision making for cytologically indeterminate thyroid nodules to targeting therapies for metastatic thyroid cancer

The Afirma Genomic Sequencing Classifier (GSC) is a rule‐out test for malignancy/noninvasive follicular thyroid neoplasms with papillary‐like nuclear features among patients with Bethesda category III/IV nodules, whereas the complimentary Xpression Atlas provides genomic insights from a curated panel of 511 genes among GSC suspicious and Bethesda category V/VI nodules. Together, they facilitate personalized treatment decisions based on genomic insights derived from the transcriptome of the biopsied target and extend the diagnostic and therapeutic reach of cytopathologists and fine‐needle aspiration biopsy sample collection.

Update on Molecular Testing for Cytologically Indeterminate Thyroid Nodules

Fine needle aspiration biopsy (FNAB) and ultrasonography are the most common modalities for the diagnosis and follow up of thyroid nodules. FNAB is able to distinguish benign from malignant nodules with high sensitivity and specificity; however, 20% to 30% of nodules are diagnosed as indeterminate with a risk of malignancy varying from 10% to 75% based on the 2017 revision of the Bethesda System for Reporting Thyroid Cytopathology. Molecular tests are being increasingly used to triage this group of nodules. Several molecular tests are commercially available and newer upgrades are being developed to either "rule in" or "rule out" malignancy with greater accuracy. The Afirma gene expression classifier and its recent upgrade (the Afirma gene sequencing classifier), Thryoseq v2, a next generation sequencing test and its recent upgrade (the v3), RosettaGX Reveal based on microRNA alterations, and ThyGenX/ThyraMIR, a combination test, are currently on the market. Familiarity with these tests, their performance, and postvalidation publications will enable appropriate test selection and improve triage of patients for appropriate therapy. The underlying rate of malignancy at different institutions and the interobserver variability in cytologic and histologic diagnosis of thyroid lesions are important factors that impact the performance of the various molecular tests.

Tumor Growth Rate Does Not Predict Malignancy in Surgically Resected Thyroid Nodules Classified as Bethesda Category III with Architectural Atypia

BACKGROUND

It is unknown whether the growth of thyroid nodules with a Bethesda category III cytology (atypia of undetermined significance [AUS]) is predictive of malignancy, especially in cases with architectural atypia (AUS-A). This study evaluated whether tumor growth rates can help distinguish malignant from benign nodules in the AUS-A subcategory.

METHODS

This retrospective, single-center cohort study included 172 patients who underwent diagnostic thyroid surgery because of a nodule with a cytological diagnosis of AUS-A. The growth kinetics of nodules was assessed by serial preoperative neck ultrasonography over a median follow-up of 52.6 months (range 12.7-198.3 months).

RESULTS

Pathologic examinations showed that 112 (65%) and 60 (35%) patients had benign and malignant nodules, respectively. The largest diameter and volume of both benign and malignant nodules increased gradually (p < 0.001). However, there was no significant difference in the growth rates of benign and malignant nodules based on the largest diameter (p = 0.132) and volume (p = 0.200). The time to tumor growth curves and estimated median time to significant tumor growth from baseline were not significantly different in malignant nodules compared to benign nodules (p = 0.458 and p = 0.568, respectively). The relative risk (RR) of malignancy of growing and stable nodules did not differ significantly based on the largest diameter (RR = 0.5; p = 0.064) and volume (RR = 0.9; p = 0.748).

CONCLUSIONS

The size of thyroid nodules classified as AUS-A increased linearly, regardless whether these nodules were benign or malignant. These results suggest that growth kinetics on serial preoperative neck ultrasonography cannot predict malignancy in the AUS-A subcategory.

Updates in Thyroid Cytology

Genomic, clinical, and pathologic studies have prompted a more risk-stratified approach to the management of patients with thyroid nodules. The recent nomenclature change concerning noninvasive follicular thyroid neoplasm with papillary-like nuclear features reflects the clinical trend toward conservative treatment choices for carefully selected low-risk thyroid neoplasms. These developments have occurred in parallel with a growing array of molecular tests intended to improve clinical triage for patients with indeterminate fine needle aspiration diagnoses. This review discusses the implications of the nomenclature revision on the interpretation of thyroid fine needle aspiration and updates available ancillary molecular tests for thyroid fine needle aspirations.

Standardized terminology systems in cytopathology

There has been increasing pressure for systemization in cytopathology. Lack of uniformity in categorization, variation in opinion based regional practice, and technologic advancement have created an environment disposed toward creation of more consistent evidence-based approaches to diagnostic problems. This review provides an overview of the major standardized terminology systems in cytology, with historical perspectives and commentary on current uses of these systems. These systems now include gynecologic, thyroid, pancreaticobiliary, urinary, salivary gland, and breast cytology. We summarize major classification systems supported by national and international professional organizations, outlining the structure and goals of each system. Specific benefits and potential pitfalls in the implementation of each system are given. Finally, we address potential criticisms of standardized terminology systems and proposed future directions to continue the evolution of standardized terminology to improve clinical practice.

Thyroid surgery for differentiated thyroid cancer - recent advances and future directions

Population-based studies have demonstrated that an increasing number of incidental thyroid nodules are being identified. The corresponding increase in thyroid-based diagnostic procedures, such as fine-needle aspiration biopsy, has in part led to an increase in the diagnoses of thyroid cancers and to more thyroid surgeries being performed. Small papillary thyroid cancers account for most of this increase in diagnoses. These cancers are considered to be low risk because of the excellent patient outcomes, with a 5-year disease-specific survival of >98%. As a result, controversy remains regarding the optimal management of newly diagnosed differentiated thyroid cancer, as the complications related to thyroidectomy (primarily recurrent laryngeal nerve injury and hypoparathyroidism) have considerable effects on patient quality of life. This Review highlights current debates, including undertaking active surveillance versus thyroid surgery for papillary thyroid microcarcinoma, the extent of thyroid surgery and lymphadenectomy for low-risk differentiated thyroid cancer, and the use of molecular testing to guide decision-making about whether surgery is required and the extent of the initial operation. This Review includes a discussion of current consensus guideline recommendations regarding these topics in patients with differentiated thyroid cancer. Additionally, innovative thyroidectomy techniques (including robotic and transoral approaches) are discussed, with an emphasis on patient preferences around decision-making and outcomes following thyroidectomy.

Preoperative Molecular Markers in Thyroid Nodules

The need for distinguishing benign from malignant thyroid nodules has led to the pursuit of differentiating molecular markers. The most common molecular tests in clinical use are Afirma^® Gene Expression Classifier (GEC) and Thyroseq^® V2. Despite the rapidly developing field of molecular markers, several limitations exist. These challenges include the recent introduction of the histopathological diagnosis "Non-Invasive Follicular Thyroid neoplasm with Papillary-like nuclear features", the correlation of genetic mutations within both benign and malignant pathologic diagnoses, the lack of follow-up of molecular marker negative nodules, and the cost-effectiveness of molecular markers. In this manuscript, we review the current published literature surrounding the diagnostic value of Afirma^® GEC and Thyroseq^® V2. Among Afirma^® GEC studies, sensitivity (Se), specificity (Sp), positive predictive value (PPV), and negative predictive value (NPV) ranged from 75 to 100%, 5 to 53%, 13 to 100%, and 20 to 100%, respectively. Among Thyroseq^® V2 studies, Se, Sp, PPV, and NPV ranged from 40 to 100%, 56 to 93%, 13 to 90%, and 48 to 97%, respectively. We also discuss current challenges to Afirma^® GEC and Thyroseq^® V2 utility and clinical application, and preview the future directions of these rapidly developing technologies.