Assessing Predictive Utility of Ultrasound for Tumor Characteristics in Thyroid Cancer

Abstract

ABSTRACT Objective To evaluate the accuracy of preoperative ultrasound in estimating tumor size, multifocality, and extrathyroidal extension in papillary thyroid carcinoma. Methods A retrospective cohort study was conducted at a tertiary referral center, including patients who underwent curative surgery for papillary thyroid carcinoma between 2006 and 2022. Agreement between preoperative ultrasound‐estimated and postoperative pathologic tumor size was assessed overall and across predefined size categories (≤ 1 cm, 1–2 cm, 2–3 cm, 3–4 cm, and > 4 cm). The diagnostic performance of ultrasound for detecting multifocality and extrathyroidal extension was also evaluated. Results The medical records of a total of 931 patients were reviewed. The mean sonographic and pathologic tumor sizes were 2.10 ± 1.42 cm and 1.64 ± 1.28 cm, respectively ( p < 0.001). Ultrasound consistently overestimated tumor size across all groups, with the mean percentage difference rising from 6% in tumors ≤ 1 cm to 32% in tumors > 4 cm ( p < 0.001). The overall mean percent difference was +15.7 ± 40.7%, indicating bias toward larger sonographic measurements. Ultrasound detection of extrathyroidal extension showed a positive predictive value of 30% and a negative predictive value of 95%; a positive predictive value of 40% and a negative predictive value of 85% for multifocality. Conclusion Our findings indicate that ultrasound tends to overestimate tumor size and that it has limited predictive accuracy for multifocality and extrathyroidal extension. They demonstrate the need for caution when planning a total thyroidectomy based solely upon preoperative ultrasound findings in the absence of suspected nodal metastasis. Level of Evidence 3.