Association of preoperative US features and recurrence in patients with classic papillary thyroid carcinoma

Purpose: To investigate whether ultrasonographic (US) features of thyroid nodules are associated with tumor recurrence in classic papillary thyroid carcinoma (PTC). Materials and Methods: This retrospective study was approved by the Institutional Review Board, and the need to obtain informed consent was waived. A total of 515 patients (mean age, 45.8 years ± 13.2 [standard deviation]; range, 17-80 years) who underwent total thyroidectomy and central lymph node dissection for classic PTC greater than 10 mm from January 2003 to February 2006 and who were followed up for 12 months or longer were included. Malignant-appearing PTCs were defined as those showing at least one suspicious US feature among marked hypoechogenicity, irregular or microlobulated margin, microcalcifications, and taller-than-wide shape. Benign-appearing PTCs were defined as those without any suspicious US features. Kaplan-Meier cumulative-event curves for recurrence were compared by using the log-rank test. The multivariate Cox proportional hazard regression analysis was used to estimate hazard ratios (HRs) of the malignant-appearing US features for recurrence in the preoperative, postoperative, and combined models. Results: Fifty-six (10.9%) of 515 patients had recurrence. Malignant-appearing PTCs had lower 5-and 10-year diseasefree survival rates compared with benign-appearing PTCs (P =.01). In the preoperative model, malignant-appearing US features (HR, 3.523; 95% confidence interval [CI]: 1.263, 9.830) and larger nodule size (HR, 1.074; 95% CI: 1.051, 1.098) were independently associated with recurrence. In the combined model, male sex (HR, 1.990; 95% CI: 1.098, 3.610), malignant-appearing US features (HR, 2.828; 95% CI: 1.016. 7.870), larger nodule size (HR, 1.067; 95% CI: 1.043, 1.092), extrathyroidal extension (HR, 2.590; 95% CI: 1.160, 5.780), and lymph node metastasis (HR, 2.511; 95% CI: 1.163, 5.421) were independently associated with recurrence. Conclusion: The presence of malignant-appearing US features was independently associated with recurrence in patients with classic PTC.