Ultrasound Alone Can Diagnose Most Thyroid Nodules

TOPLINE:
Ultrasound (US) alone appears an effective for diagnosing thyroid nodules, confirming two recommendations of recent guidelines and the British Thyroid Association’s classification.
However, findings also suggest caution regarding existing recommendations for conservative management of non-diagnostic and atypical nodules, for which US features may help identify high-risk subgroups for more proactive management.
METHODOLOGY:
The secondary outcomes of the ElaTION study that compared elastography US-guided fine needle aspiration cytology (FNAC) with US-guided FNAC.
A total of 688 adults with single or multiple thyroid nodules were assessed with US alone and US-FNAC, and received final definitive diagnoses: 22% (n = 149) were malignant and 78% (n = 539) benign.
TAKEAWAY:
The sensitivity was 0.91 for US alone vs 0.87 for US-FNAC, not a significant difference (P = .37).
For diagnosing malignant nodules, US alone would have missed 9% (n = 7/77) of cases, whereas US-FNAC would have missed 13% (10/77) of malignancies, a non-significant difference.
For diagnosing benign nodules, US alone had statistically significant lower specificity than US-FNAC (0.48 vs 0.67; P < .0001).
The risk for malignancy in a nodule classified as benign on US (U2) was 3.42% (n = 9/263) and those benign on cytology (Thy 2[Bethesda II]) 4.25%, whereas the risk for a nodule that was benign on both (U2, Thy2 [Bethesda II]) was 1.43% (n = 3/210).
Compared with a benign (U2) nodule (3.42%), the risk for malignancy for an indeterminate/equivocal (U3) nodule was 22.4% (n = 68/304), for a nodule suspicious for malignancy (U4) was 51.8% (n = 43/83), and for a diagnostic for malignancy (U5) nodule was 76.3% (n = 29/38); P < .0001.
No nodules classified as malignant on cytology (Thy 4 or 5) had a benign US classification, and none classified as malignant on US (U4 or 5) had benign (Thy2) cytology.
IN PRACTICE:
“This is largest prospective multicentre evaluation of the efficacy of [US] alone compared with US-FNAC for the diagnosis of thyroid nodules. It therefore provides important data to validate some of the main changes in recommendations that have been advocated by recent thyroid cancer guidelines,” the authors wrote. “We encourage guidelines committees to consider this new high-level evidence, which confirms many of [the guideline] recommendations [that are] based on lower quality evidence,” they added.
SOURCE:
Conducted by Hisham Mehanna, PhD, Institute of Head and Neck Studies and Education (InHANSE), Institute of Cancer and Genomic Sciences, University of Birmingham, UK, and colleagues, the study was published online October 3, 2024, in the Journal of Clinical Endocrinology and Metabolism.
LIMITATIONS:
Not formally powered to assess differences in malignancy rates and accuracy of US or US-FNAC alone, particularly in some patient subsets. Seven of the 20 participating centres selected 70% of the cases. Over half of non-diagnostic (Thy1/Bethesda 1) were discharged without receiving a final diagnosis.
DISCLOSURES:
The study was funded by the National Institute for Health and Care Research. Hisham Mehanna reported grants from UK National Institute of Health Research, Cancer Research UK, the UK Medical Research Council, and AstraZeneca, advisory board fees from AstraZeneca, MSD, Merck, Nanobiotix, and Seagen. He is Director of Warwickshire Head & Neck Clinic and Docspert Health.
 
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