Thyroid Nodules With Nondiagnostic Cytologic Results: Follow-Up Management Using Ultrasound Patterns Based on the 2015 American Thyroid Association Guidelines

Assessment of diagnostic capacity and decision-making based on the 2015 American Thyroid Association ultrasound classification system

BACKGROUND

This study evaluates the American Thyroid Association (ATA) ultrasound (US) classification system for the initial assessment of thyroid nodules to determine if it indeed facilitates clinical decision-making.

AIM

To perform a systematic review and meta-analysis of the diagnostic value of the ATA US classification system for the initial assessment of thyroid nodules.

METHODS

In accordance with the PRISMA statement for diagnostic test accuracy, we selected articles that evaluated the 2015 ATA US pattern guidelines using a diagnostic gold standard. We analyzed these cases using traditional diagnostic parameters, as well as the threshold approach to clinical decision-making and decision curve analysis.

RESULTS

We reviewed 13 articles with 8445 thyroid nodules, which were classified according to 2015 ATA patterns. Of these, 46.62% were malignant. No cancer was found in any of the ATA benign pattern nodules. The Bayesian analysis post-test probability for cancer in each classification was: (1) Very-low suspicion, 0.85%; (2) Low, 2.6%; (3) Intermediate, 6.7%; and (4) High, 40.9%. The net benefit (NB), expressed as avoided interventions, indicated that the highest capacity to avoid unnecessary fine needle aspiration biopsy (FNAB) in the patterns that we studied was 42, 31, 35, and 43 of every 100 FNABs. The NB calculation for a probability threshold of 11% for each of the ATA suspicion patterns studied is less than that of performing FNAB on all nodules.

CONCLUSION

These three types of analysis have shown that only the ATA high-suspicion diagnostic pattern is clinically useful, in which case, FNAB should be performed. However, the curve decision analysis has demonstrated that using the ATA US risk patterns to decide which patients need FNAB does not provide a greater benefit than performing FNAB on all thyroid nodules. Therefore, it is likely that a better way to approach the assessment of thyroid nodules would be to perform FNAB on all non-cystic nodules, as the present analysis has shown the ATA risk patterns do not provide an adequate clinical decision-making framework.

Comparison of Four Ultrasonography-Based Risk Stratification Systems in Thyroid Nodules with Nondiagnostic/Unsatisfactory Cytology: A Real-World Study

Simple Summary

Although ultrasound-based risk stratification systems (RSSs) including Thyroid Imaging, Reporting and Data Systems (TIRADSs) may play an important role in triaging nodules with nondiagnostic/unsatisfactory cytology, no previous studies have compared ultrasound-based RSSs for these nodules. In this retrospective, longitudinal, real-world study in Korea including 1143 thyroid aspirations with nondiagnostic/unsatisfactory results from 1125 patients, further diagnostic evaluations, including repeat fine-needle aspiration, were conducted more commonly as the categories of ultrasound-based RSSs increased. The American Thyroid Association (ATA) guidelines, Korean (K)-TIRADS, and American College of Radiology (ACR) TIRADS were more competent in predicting malignancy from nondiagnostic/unsatisfactory nodules. The EU-TIRADS, although it was also helpful, demonstrated less effective diagnostic performance in predicting malignancy for nondiagnostic/unsatisfactory nodules in Korea, where iodine intake is more than adequate. These findings have implications for developing and verifying universal guidelines for the ultrasound-based stratification of thyroid nodules and applying these guidelines to nondiagnostic/unsatisfactory nodules.

Abstract

We compared American Thyroid Association (ATA) guidelines, Korean (K)-Thyroid Imaging, Reporting and Data Systems (TIRADS), EU-TIRADS, and American College of Radiology (ACR) TIRADS in diagnosing malignancy for thyroid nodules with nondiagnostic/unsatisfactory cytology. Among 1143 nondiagnostic/unsatisfactory aspirations from April 2011 to March 2016, malignancy was detected in 39 of 89 excised nodules. The minimum malignancy rate was 7.82% in EU-TIRADS 5 and 1.87–3.00% in EU-TIRADS 3–4. In the other systems, the minimum malignancy rate was 14.29–16.19% in category 5 and ≤3% in the remaining categories. Although the EU-TIRADS category ≥ 5 exhibited the highest positive likelihood ratio (LR) of only 2.214, category ≥ 5 in the other systems yielded the highest positive LR of >5. Receiver operating characteristic (ROC) curves of all systems to predict malignancy were located statistically above the diagonal nondiscrimination line (P for ROC curve: EU-TIRADS, 0.0022; all others, 0.0001). The areas under the ROC curve (AUCs) were not significantly different among the four systems. The ATA guidelines, K-TIRADS, and ACR TIRADS may be useful to guide management for nondiagnostic/unsatisfactory nodules. The EU-TIRADS, although also useful, exhibited inferior performance in predicting malignancy for nondiagnostic/unsatisfactory nodules in Korea, an iodine-sufficient area.

Development and Internal Validation of a Predictive Model for Individual Cancer Risk Assessment for Thyroid Nodules

OBJECTIVE

The objective of this study was to develop and validate a predictive model for the assessment of the individual risk of malignancy of thyroid nodules based on clinical, ultrasound, and analytic variables.

METHODS

A retrospective case-control study was carried out with 542 patients whose thyroid nodules were analyzed at our endocrinology department between 2013 and 2018 while undergoing treatment for thyroidectomy. Starting with a multivariate logistic regression analysis, which included clinical, analytic, and ultrasound variables, a predictive model for thyroid cancer (TC) risk was devised. This was then subjected to a cross-validation process, using resampling techniques.

RESULTS

In the final model, the independent predictors of the risk of malignancy were: being male, age of the extremes, family history of TC, thyroid-stimulating hormone level >4.7 μU/L, presence of autoimmune thyroiditis, solid consistency, hypoechogenicity, irregular or microlobed borders, nodules that are taller than they are wide, microcalcifications, and suspicious adenopathy. With a cut-off point of 50% probability of thyroid cancer, the predictive model had an area under the receiver operating characteristic curve of 0.925 (95% confidence interval 0.898 to 0.952). Finally, using the 10-fold cross-validation method, the accuracy of the model was found to be 88.46%, with a kappa correlation coefficient of 0.62.

CONCLUSION

A predictive model for the individual risk of malignancy of thyroid nodules was developed and validated using clinical, analytic, and ultrasound variables. An online calculator was developed from this model to be used by clinicians to improve decision-making in patients with thyroid nodules.

The combination of ATA classification and FNA results can improve the diagnostic efficiency of malignant thyroid nodules

PURPOSE

To determine the diagnostic efficiency of the ATA classification and ultrasound-guided fine-needle aspiration (FNA) results in identifying the risk factors of malignancy, we analyzed the thyroid nodules of patients who underwent thyroidectomy and compared preoperative ATA classifications with FNA results.

METHODS

We retrospectively analyzed 274 nodules of 196 patients who underwent ultrasonography, FNA and thyroidectomy. Histopathological findings of thyroid nodules were considered as the Au standard in the analysis of the diagnostic efficiency of the ATA classification and FNA results. Univariate analysis and binary multivariate logistic regression analysis were applied to identify the ultrasound features associated with malignancy.

RESULTS

The overall malignancy rate of 274 nodules was 41.6%. The areas under the ROC curves (AUCs) for the ATA classification and FNA results were 0.88 and 0.878, respectively (P < 0.001). The sensitivity and specificity of the ATA classification were 86 and 86.9%, whereas those of FNA results were 68.5 and 91.4%, respectively. The specificity (98.7%) and sensitivity (94.3%) increased after the combined use of the ATA classification and FNA results. Taller-than-wide shape, microcalcifications, hypoechogenicity and irregular margins were independent risk factors for malignancy. Microcalcifications had the highest OR (7.58), and taller-than-wide shape had the highest specificity in BSRTC I, II, III and IV cytology.

CONCLUSION

The diagnostic efficiency of the ATA classification and FNA results in identifying malignant nodules was high, and the use of both criteria improved the diagnostic accuracy. Taller-than-wide shape, microcalcifications, hypoechogenicity and irregular margins were independent risk factors for malignancy.

Contemporary Thyroid Nodule Evaluation and Management

CONTEXT

Approximately 60% of adults harbor 1 or more thyroid nodules. The possibility of cancer is the overriding concern, but only about 5% prove to be malignant. The widespread use of diagnostic imaging and improved access to health care favor the discovery of small, subclinical nodules and small papillary cancers. Overdiagnosis and overtreatment is associated with potentially excessive costs and nonnegligible morbidity for patients.

EVIDENCE ACQUISITION

We conducted a PubMed search for the recent English-language articles dealing with thyroid nodule management.

EVIDENCE SYNTHESIS

The initial assessment includes an evaluation of clinical risk factors and sonographic examination of the neck. Sonographic risk-stratification systems (e.g., Thyroid Imaging Reporting and Data Systems) can be used to estimate the risk of malignancy and the need for biopsy based on nodule features and size. When cytology findings are indeterminate, molecular analysis of the aspirate may obviate the need for diagnostic surgery. Many nodules will not require biopsy. These nodules and those that are cytologically benign can be managed with long-term follow-up alone. If malignancy is suspected, options include surgery (increasingly less extensive), active surveillance or, in selected cases, minimally invasive techniques.

CONCLUSION

Thyroid nodule evaluation is no longer a 1-size-fits-all proposition. For most nodules, the likelihood of malignancy can be confidently estimated without resorting to cytology or molecular testing, and low-frequency surveillance is sufficient for most patients. When there are multiple options for diagnosis and/or treatment, they should be discussed with patients as frankly as possible to identify an approach that best meets their needs.

Diagnostic performance of the American Thyroid Association ultrasound risk assessment of thyroid nodules in endocrinology (the ETIEN 3 study)

INTRODUCTION

No study has been published to date in Spain about the value of the American Thyroid Association (ATA) ultrasound risk assessment of thyroid nodules applied by endocrinologists.

OBJECTIVES

To assess the diagnostic performance of ATA thyroid nodule risk classification applied by endocrinologists with respect to histological results.

METHODS

A retrospective, observational study of 317 patients (mean age, 51.7±13.7 years; 83.3% women) with thyroid nodules (maximum diameter: 3.2±1.4cm) who underwent US-guided FNA in endocrinology between October 2015 and December 2018, were classified based on the ATA ultrasound risk assessment. Surgery was performed in all of them. Quality criteria of the ultrasound classification were assessed as compared to histological results.

RESULTS

Overall, 61.2% of nodules assessed were classified as benign (n=3) and very low (n=60) or low suspicion (n=131), 11.7% as intermediate suspicion (n=37), and 27.1% as high suspicion (n=86). Benign nodular disease was found in 260 patients, and thyroid cancer in 57 patients. There were 14 incidental papillary microcarcinomas. Classification of thyroid nodules as high suspicion showed a high diagnostic performance to identify malignant nodules (87.7% sensitivity, 86.2% specificity, negative predictive value 97.0%), improving sensitivity (93.0%) and reducing specificity (73.1%) when considering high and intermediate suspicion nodules as a risk for thyroid cancer.

CONCLUSIONS

Application by endocrinologists of the ATA ultrasound risk assessment of thyroid nodules shows a high diagnostic performance to identify malignant thyroid nodules before surgery.