Predictive Factors of Central Lymph Node Metastasis in Papillary Thyroid Microcarcinoma / 대한내분비외과학회지

PURPOSE: Despite the excellent overall prognosis for patients with papillary thyroid microcarcinoma (PTMC), the rate of central lymph node (CLN) metastasis has been reported to be as great as 60% and the optimal surgical extent of PTMC has been controversial. The aim of this study is to identify factors for predict CLN metastasis in patients with PTMC. METHODS: We conducted a retrospective study of 535 patients with PTMC who underwent total thyroidectomy with prophylactic CLN dissection between Jan. 2008 and Aug. 2011. We analyzed the association of CLN metastasis and clinicopathologic characteristics. RESULTS: CLN metastasis was found in 181 patients (33.8%). Results of univariate analysis showed an association of younger than 45 years of age, male gender, a tumor size greater than 5 mm, bilaterality, multiplicity, extrathyroidal extension, and positivity of resection margin with CLN metastasis. Of these, results of multivariate analysis showed that age (P=0.003), gender (P=0.004), tumor size (P5 mm), male gender, young age (<45 yr), extrathyroidal extension, and positive resection margin were determined as the predictive factors for CLN metastasis, which occurred in approximately one third of patients with PTMC. Therefore, prophylactic CLN dissectionshould be considered in patients with PTMC who have these factors through investigation before surgery.

Morbidity of Lymph Node Dissection in Central Neck Area for Operations of Differentiated Thyroid Carcinoma

PURPOSE: To date, the benefits of central neck node dissection (CND) in patients with differentiated thyroid carcinoma (DTC) have not been clearly demonstrated and must be considered against the potential risks of the procedure. However, recent papers suggest that lymph node metastasis exerts a significant influence on survival and is associated with a higher risk of recurrence. The purpose of our study was to assess the recurrent laryngeal nerve and parathyroid risks of CND following total thyroidectomy in patients with DTC and to compare the results with those obtained in patients who underwent total thyroidectomy only. METHODS: We retrospectively analysed 143 consecutive patients with DTC (116 with papillary, 24 with follicular, and 3 with Hurthle cell carcinoma) operated on by a single experienced endocrine surgeon from January 1989 to January 1999. There were 61 total thyroidectomies with CND (Group 1) and 82 total thyroidectomies only (Group 2). Group 1 patients displayed evidence of macroscopic lymph node invasion during surgery. The definitions of the two main complications in the thyroid surgery were as follows: transient and permanent recurrent laryngeal nerve palsy (persisting hoarseness over six months after thyroidecomy), transient and permanent hypoparathyroidism (non-recovery of normal parathyroid function and calcemia below 8.0 mg/dl over six momths after thyroidectomy). RESULTS: There was no difference observed in the demographic data between the two groups. Three cases (4.9%) of transient hypocalcemia were detected in Group 1 and two cases (2.4%) in Group 2. Five cases (8.2%) of transient nerve palsy were presented in Group 1 and one case (1.2%) in Group 2. However, there was no significant statistical difference between the two groups (p=0.051). None of the patients demonstrated permanent nerve palsy. CONCLUSION: Following total thyroidectomy for DTC, CND does not increase the morbidity of parathyroid gland and recurrent laryngeal nerve. Therefore, in order to decrease the incidence of regional recurrence and avoid the risk of reoperation in the central neck area, we recommend cervical neck node dissection from the central neck compartment concomitant with total thyroidectomy when overt lymph nodes are palpated.