Long-Term Outcomes of Total Thyroidectomy Versus Thyroid Lobectomy for Papillary Thyroid Microcarcinoma: Comparative Analysis After Propensity Score Matching

Aims: The objectives of this study were to compare long-term outcomes after total thyroidectomy (TT) or thyroid lobectomy (LT) in a large cohort of patients with papillary thyroid microcarcinoma (PTMC), and to determine whether tumor size (0.5cm vs. >0.5cm) has a significant impact on the extent of surgery. Methods: We evaluated 2014 patients with PTMC who underwent TT with central compartment node dissection (CCND; n=1015) or LT with CCND (n=999) between March 1986 and December 2006 and for whom complete follow-up data were available for at least 5 years (median 11.8 years, range 5-26 years). Using propensity score matching to reduce the impact of treatment selection bias and potential confounding in an observational study, we compared overall survival and disease-free survival in the overall cohort and in patients with tumors 0.5cm and >0.5cm in size. Results: After adjustment for differences in baseline clinicopathologic risk factors, we observed no significant differences between the LT and the TT groups in the risk of death (hazard ratio for the LT group 1.05, 95% confidence interval [CI] 0.71-1.47, p=0.890) and locoregional recurrence (hazard ratio for the LT group 3.08 [CI 1.99-8.05], p=0.194) in the overall matched cohort. Similar results were observed when we compared LT and TT in patients with tumors 0.5cm and >0.5cm. Conclusions: The long-term rates of death and locoregional recurrence were similar in patients with PTMC who underwent LT with CCND and those who underwent TT with CCND. Therefore, completion thyroidectomy may not be recommended unless recurrence after LT is definitely detected in low-risk PTMC patients, and close follow-up is adequate in these patients. Moreover, tumor size greater than or less than 0.5cm was not a significant determinant of the extent of surgery in patients with PTMC.