Diagnostic Value of Molecular Testing in Sonographically Suspicious Thyroid Nodules

Maxwell M Wang; Katrina Beckett; Michael Douek; Rinat Masamed; Maitraya Patel; Chi-Hong Tseng; Michael W Yeh; Angela M Leung; Masha J Livhits

doi:10.1210/jendso/bvaa081

Diagnostic Value of Molecular Testing in Sonographically Suspicious Thyroid Nodules

J Endocr Soc. 2020 Jun 20;4(9):bvaa081. doi: 10.1210/jendso/bvaa081. eCollection 2020 Sep 1.

Authors

Maxwell M Wang¹, Katrina Beckett², Michael Douek², Rinat Masamed², Maitraya Patel², Chi-Hong Tseng³, Michael W Yeh⁴, Angela M Leung^{5

6}, Masha J Livhits⁴

Affiliations

¹ David Geffen School of Medicine at University of California at Los Angeles, Los Angeles, California.
² Department of Radiology, David Geffen School of Medicine at University of California at Los Angeles, Los Angeles, California.
³ Department of Medicine, David Geffen School of Medicine at University of California at Los Angeles, Los Angeles, California.
⁴ Section of Endocrine Surgery, David Geffen School of Medicine at University of California at Los Angeles, Los Angeles, California.
⁵ Division of Endocrinology, Diabetes, and Metabolism, David Geffen School of Medicine at University of California at Los Angeles, Los Angeles, California.
⁶ Division of Endocrinology, Diabetes, and Metabolism; VA Greater Los Angeles Healthcare System, Los Angeles, California.

Abstract

Objective: Molecular testing can refine the diagnosis for the 20% of thyroid fine-needle aspiration biopsies that have indeterminate cytology. We assessed the diagnostic accuracy of molecular testing based on ultrasound risk classification.

Methods: This retrospective cohort study analyzed all thyroid nodules with indeterminate cytology at an academic US medical center (2012-2016). All indeterminate nodules underwent reflexive molecular testing with the Afirma Gene Expression Classifier (GEC). Radiologists performed blinded reviews to categorize each nodule according to the American Thyroid Association (ATA) ultrasound classification and the American College of Radiology Thyroid Imaging, Reporting and Data System. GEC results and diagnostic performance were compared across ultrasound risk categories.

Results: Of 297 nodules, histopathology confirmed malignancy in 65 (22%). Nodules by ATA classification were 8% high suspicion, 44% intermediate, and 48% low/very low suspicion. A suspicious GEC result was more likely in ATA high-suspicion nodules (81%) than in nodules of all other ATA categories (57%; P = .04). The positive predictive value (PPV) of GEC remained consistent across ultrasound categories (ATA high suspicion, 64% vs all other ATA categories, 48%; P = .39). The ATA high-suspicion category had higher specificity than a suspicious GEC result (93% vs 51%; P < .01). A suspicious GEC result did not increase specificity for the ATA high-suspicion category.

Conclusion: The PPV of molecular testing remained consistent across ultrasound risk categories. However, a suspicious GEC result was very likely in ATA high-suspicion nodules and did not improve specificity in this sonographic category.

Keywords: molecular testing; ACR TI-RADS; ATA; nodule; thyroid; ultrasound.