Extrathyroidal extension on ultrasound in patients with papillary thyroid carcinoma: is it associated with local lymph node metastasis?

Abstract

Introduction:The association of extrathyroidal extension (ETE) with local lymph node metastases in patients with papillary thyroid cancer assessed by ACR TI-RADS has not been sufficiently studied. This study aimed to evaluate ACR TI-RADS ultrasonographic features of thyroid nodules in patients with papillary thyroid cancer and define their association with histopathology-confirmed local lymph node metastases. Material and methods: This study was a retrospective cohort of patients with surgically treated papillary thyroid carcinoma evaluated preoperatively with thyroid ultrasound. The odds ratio (OR) for all ultrasonographic ACR TI-RADS criteria was calculated with binary logistic regression. The sensitivity, specificity, and accuracy of ultrasound and a ROC analysis to define the optimal cutoff point of tumor size for detecting ETE were calculated. A p-value < 0.05 was statistically significant. Results: Seventy thyroid nodules from 57 patients with papillary thyroid cancer were included. An association with histopathology-confirmed local lymph node metastases was found in 29 (41.4%) thyroid nodules and ETE demonstrated by ultrasound had an increased risk of local lymph node metastasis (OR 6.50,. ETE detection by ultrasound showed a diagnostic accuracy of 85.7%, a sensitivity of 57.1%, and a specificity of 95.2%. ROC analysis showed that a tumor size of 15.5 mm was the optimal cutoff point for ETE-detection by ultrasound and histopathology. Conclusions: This study is the first in Mexico to demonstrate that ultrasonographic findings of ETE in thyroid nodules were associated with local lymph node metastases in patients with papillary thyroid cancer.