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

Abstract

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.