A Prospective, Open-label, Multicenter, Randomized Controlled Phase III Study of Prophylactic Central Neck Dissection in Low-risk Papillary Thyroid Cancer

Inclusion Criteria: \- (1)Patients age 18-70 years old, ECOG score 0-2; (2)Thyroid nodule measuring 11-40 mm on ultrasound (cT1bT2) and with fine-needle aspiration biopsy (FNAB) cytology in favor of "papillary thyroid carcinoma" or with intraoperative frozen section analysis "papillary thyroid carcinoma" . (3)cN0: absence of lymph nodes suspicious for malignancy on preoperative ultrasound performed by the center's designated radiologist according to a standardized report, no gross extrathyroidal extension was found before or during the surgery; (4)No serious medical disease and dysfunction of major organs, such as blood routine, liver, kidney, heart, and lung function; no previous history of other head and neck malignancies, no history of neck radiation, no history of deep neck surgery (skin mass resection except clinical); (5)Patients should understand, sign and date the written informed consent form prior to any protocol specific procedures. Patients should be able and willing to comply with study visits. Exclusion Criteria: -(1)History of malignancy in other sites (previous or concurrent), excluding curable non-melanoma skin cancer and cervical carcinoma in situ; (2)Tumors \> 40 mm (cT3) or ≤ 10 mm; tumors with extrathyroidal extension suspected or obvious on the pre-operative work-up or intra-operatively; (3)Metastatic neck lymph nodes or suspicious neck nodes on preoperative ultrasound (cN1); for suspicious nodes, FNAB cytology and thyroglobulin assay on the needle washout fluid will be performed.Metastatic neck lymph nodes found during the thyroidectomy and confirmed with intra-operative frozen section analysis. (4)No papillary thyroid carcinoma on FNAB cytology and/or high-risk subtype PTC; (5)Pregnant or breast feeding women (6)Participation in another therapeutic clinical trial within four months from study entry