Table 1.

The inclusion and exclusion criteria for the included patients.

Inclusion criteria	Exclusion criteria
(1) Large solid thyroid nodules with the volume more than 25 ml; (2) benign lesions confirmed by US examinations; (3) reaching normal and clear cytologic results in US-guided core-needle biopsy; (4) ordinary serum thyroid hormone degree and normal calcitonin level; and (5) obvious neck symptoms or cosmetic concerns.	(1) Contraindications to RFA; (2) serious cardiopulmonary diseases; (3) severe coagulation disorders; (4) without available clinical records; and (5) unwilling to receive RFA.