The purpose of this study is to determine whether the prophylactic ipsilateral central lymph node dissection is equally effective in the management of papillary thyroid microcarcinoma(PTMC) to the bilateral central lymph node dissection.

The extent, the advantage and disadvantage of prophylactic central lymph node dissection was not fully established up to now in papillary thyroid microcarcinoma.

Prophylactic bilateral central lymph node dissection can give a important clinical information about the status of lymph nodes, and possibly guide a further adjuvant treatment. However, it causes high postoperative morbidity, including hypocalcemia and hoarseness. In this respect, some advocate no central lymph node dissection in prophylactic settings.

Thus, we aimed to prove the efficacy of prophylactic ipsilateral central lymph node dissection in thyroid papillary microcarcinoma, compared to the bilateral dissection and no dissection.

Type of Study design: Prospective randomized, controlled double-blinded (to subjects and observers) study.

Group I: Limited/ipsilateral central lymph node dissection (UniCND) Group II: Comprehensive/bilateral central lymph node dissection (BiCND) Group III: No central lymph node dissection (NoCND)

Outcomes: vocal cord palsy, hypocalcemia, locoregional recurrence, distant metastasis

Inclusion Criteria:

• Age: 18 to 70
• Sonographically node-negative cytology confirmed thyroid papillary carcinoma
• Tumor size less than 1 cm in sonography
• Tumor confined to the one lobe of the thyroid gland
• One who provides the informed consent

Exclusion Criteria:

• History of radiation treatment to head and neck area
• History of other malignancy except thyroid cancer
• Poor performance status (ECOG 3-4)