This is a single center prospective clinical trial with regard to efficacy and safety of radiofrequency ablation of papillary thyroid microcarcinoma.

For treatment of papillary thyroid microcarcinoma (PTMC), radiofrequency ablation (RFA) will be performed with the supine position and neck extended under ultrasonogrphic guidance. Before RFA, local anesthesia will be performed. RFA system including radiofrequency generator (VIVA RF system, STARmed, Goyang-si, Korea) and internally cooled electrode (star RF electrode, STARmed, Goyang-si, Korea) will be used. With regard to RFA procedure, moving shot technique and hydrodissection, if indicated, will be used. After RFA, follow-up will be performed using ultrasonography, serum thyroid function test, and questionnaire for quality of life by face-to-face interview at 2 months, 6, 12, 18, 24 months during the first 2 years after RFA, and yearly afterwards.

Inclusion Criteria:

• who agrees to the consent form
• aged from 19 to 60 years old
• who has been diagnosed with Bethesda category V or VI by fine needle aspiration or needle biopsy
• whose thyroid cancer is 1 cm or smaller than 1 cm length
• who does not have lymph node or distant metastasis
• whose thyroid cancer does not have extrathyroidal extension
• in whom it seems technically possible to completely ablate thyroid cancer using RF

Exclusion Criteria:

• who cannot routinely followed up according to the study schedule
• who has been with Bethesda category I, II, III, or IV by fine needle aspiration or needle biopsy.
• who has hyperthyroidism that requires treatment
• who has bleeding tendency
• multifocal papillary thyroid microcarcinoma
• who is pregnant