Risk Factors of Lymph Node Metastasis in Papillary Thyroid Microcarcinoma

ABSTRACT

PURPOSE: Despite the overall excellent prognosis for patients with papillary thyroid microcarcinoma (PTMC), these tumors are also associated with a 5% relatively high lymph node (LN) recurrence rate and the optimal surgical extent of papillary thyroid microcarcinoma has been controversial. Cervical LN metastases (LNMs) are found in about 40~65% of patients with PTMC. The aim of this study is to identify the factors affecting lymph node metastases (LNMs) in patients with PTMC. METHODS: We performed a retrospective study of 335 patients with PTMC who underwent total thyroidectomy or lobectomy with elective central lymph node dissection (CLND) at Kangnam St. Mary's Hospital between Jan. 2006 and Dec. 2008. We investigated the association of LNMs and clinicopathologic factors such as sex, age, multiplicity, extrathyroidal extension, and tumor size. RESULTS: LNMs were present in 88 patients (26.3%). Univariate analysis showed that less than 45 years of age, male, multiplicity, a tumor size of greater than 5 mm, thyroid capsular invasion and extrathyroidal extension were predictive factors for LNMs (P5 mm), male, age (<45) and extrathyroidal extension were determined as the predictive factors for LNMs, which occurred in about one fourth of the patients with PTMC. Therefore, elective CLND should be considered in patients with PTMC who have these factors through a thorough investigation before surgery.