Oncologic outcomes in patients with 1-cm to 4-cm differentiated thyroid carcinoma according to extent of thyroidectomy

Background: Recent guidelines advocate unilateral thyroidectomy for low-risk 1-cm to 4-cm differentiated thyroid cancer (DTC). This study was designed to examine the association between the extent of thyroidectomy and oncologic outcomes in patients with 1-cm to 4-cm DTC. Materials and Methods: From April 1978 to December 2011, 16 057 patients with DTC underwent thyroidectomy at Yonsei University Hospital. Among them, 5266 (32.8%) patients were classified as having 1-cm to 4-cm DTC and were enrolled in this study. Clinicopathologic features and prognostic results (disease-free survival [DFS] and disease-specific survival [DSS] rates) were analyzed by retrospective medical record review. The mean follow-up duration was 57.3 ± 58.1 months. Results: Of tumor subtypes in the study group, papillary thyroid carcinoma was the most common (97.5%) and follicular thyroid carcinoma occurred at a rate of 2.5%. In this study, the mean tumor size was 1.84 ± 0.74 cm. Patients had extrathyroidal extension (69.3%), multiplicity (35.1%), bilaterality (26.4%), central lymph node metastasis (53.0%), and lateral neck node metastases (19.9%). Of the 5266 patients, 4292 (81.5%) underwent total thyroidectomy and 974 (18.5%) had lobectomies. Recurrence rates in the total thyroidectomy and lobectomy groups were 5.7% and 9.4%, respectively. The lobectomy group had lower DFS (P =.007) and higher DSS (P =.034) than the total thyroidectomy group. A multivariate analysis for DFS revealed that tumor size, N classification, and extent of thyroidectomy were independent risk factors. On multivariate analysis, independent risk factors for DSS were age, sex, tumor size, and M classifications. Conclusion: Although extent of thyroidectomy does not affect DSS, total thyroidectomy is beneficial for reducing recurrence in patients with 1-cm to 4-cm DTC. However, if such tumors have such low-risk features as being unifocal, intrathyroidal, and lymph node metastasis-negative, extent of thyroidectomy does not affect oncologic outcome and lobectomy may be sufficient.