To evaluate the feasibility and safety of gasless transaxillary posterior endoscopic thyroidectomy (Resection of thyroid lobe and isthmus, lymph node dissection in the central area of the affected side) and open radical thyroidectomy (Resection of thyroid lobe and isthmus, lymph node dissection in the central area of the affected side) as the current standard surgical treatment mode in terms of feasibility and safety of radical thyroidectomy.

Subjects that suffering from papillary thyroid carcinoma will be randomized into Study Group (gasless transaxillary posterior endoscopic thyroidectomy ) or Control Group (conventional open thyroidectomy). Measure the outcomes as following, early complication rate, life quality score, the number of dissected lymph nodes, the volume of residual gland, 3-year recurrence rate, operation duration, hospital stays, hospitalization expense, and inflammatory and immune response.

Inclusion Criteria:

• The patient's informed consent;
• 18 years old < age < 70 years old;
• Papillary thyroid carcinoma (Bethesda grade V-VI) was pathologically diagnosed by fine needle aspiration biopsy of the primary thyroid tumor before surgery;
• Color Doppler TI-RADS 4c-5 of primary thyroid tumor;
• The preoperative clinical staging is T1, N0-1a, M0 (see diagnostic criteria for details; according to AJCC-8th TNM tumor staging);
• It is expected that R0 surgical results can be obtained by performing single thyroid lobectomy and isthmus resection + ipsilateral central lymph node dissection;
• Preoperative ASA score I-III.

Exclusion Criteria:

• Pregnant or lactating patients;
• Suffering from serious mental illness;
• Preoperative imaging examinations suggest that the tumor is located in the thyroid isthmus or involves bilateral lobes;
• Preoperative imaging examinations suggest the possibility of cervical lateral lymph node or distant metastasis;
• Hashimoto's thyroiditis combined with hyperthyroidism or abnormal thyroid function;
• History of neck surgery;
• History of thyroid surgery (including ablation therapy for thyroid nodules);
• Family history of thyroid cancer;
• History of childhood ionizing radiation exposure;
• History of other malignant diseases within 5 years;
• A history of unstable angina or myocardial infarction within 6 months;
• History of cerebral infarction or cerebral hemorrhage within 6 months;
• History of continuous systemic corticosteroid therapy within 1 month;
• Concurrent surgical treatment of other diseases is required;
• Patients who are judged by the investigator to be unsuitable to participate in this trial.