Table 1.

Characteristics of the Included Studies

Group	Study	Enrollment period	Affiliation	Patient no.	Mean age	Male: female	Study design	Nodule no.	Criteria for ablation (summary of inclusion and exclusion criteria)
RFA	Aldea Martinez et al. (2019) [10]	May 2014 to Oct 2018	Hospital Universitario de Burgos, Spain	24	50.2	4:20	Retro.	24	Inclusion: symptomatic nodule, TIRADS 1 or 2, 2 consecutive Bethesda II, solid or predominantly solid nodules Exclusion: contralateral laryngeal nerve palsy, presence of pacemaker, pregnancy, cystic nodules, history of neck radiation, patient’s refusal
RFA	Deandrea et al. (2019) [11]	2011 to 2015	Mauriziano Hospital, Italy	215	66	33:182	Retro.	215	Inclusion: solid or mixed with a solid portion >70%, benign (2 consecutive Bethesda II), normal thyroid function Exclusion: RFA performed more than once
RFA	Jung et al. (2018) [12]	May 2010 to Dec 2011	Multicenter, Koreaa	276	46	43:302	Pro.	276	Inclusion: symptomatic or cosmetic problems, 2 consecutive benign cytology results, no malignant feature on US, solid (>50% solid components), predominantly cystic (10%<solid components <50%), normal thyroid function Exclusion: follicular neoplasm, primary thyroid cancer, pregnancy, history of neck radiation, cystic nodules (<10% solid components)
RFA	Lim et al. (2013) [13]	Jun 2002 to Dec 2007	Daerim St. Mary’s Hospital, Korea	111	37.9	10:101	Retro.	126	Inclusion: symptomatic or cosmetic problems, size >2 cm, 2 consecutive benign cytology results, no malignant feature on US, normal thyroid function, refused or ineligible for surgery Exclusion: NA
RFA	Sim et al. (2017) [14]	Jun 2008 to Nov 2013	Withsim Clinic, Korea	54	44.1	5:49	Retro.	54	Inclusion: symptomatic or cosmetic problems, at least 12 months of follow-up Exclusion: NA
LA	Dossing et al. (2011) [3]	1999 to 2008	Odense University Hospital, Denmark	78	46	4:74	Retro.	78	Inclusion: symptomatic or cosmetic problems, solitary, solid, cold nodule, benign cytology, normal thyroid function, normal calcitonin Exclusion: family history of thyroid cancer, history of neck radiation
LA	Gambelunghe et al. (2013) [4]	2005 to 2008	University of Perugia, Italy	40	63	NA	Retro.	40	Inclusion: symptomatic nodule, single or dominant nodule, benign cytology, cold nodule, normal thyroid function, normal calcitonin, solid, refused or for ineligible surgery, size of 5–150 mL Exclusion: NA
LA	Gambelunghe et al. (2018) [5]	2009 to 2014	University of Perugia, Italy	82	41	31:51	Retro.	82	Inclusion: toxic nodule, hot nodule, normal thyroglobulin, normal calcitonin, normal anti-thyroglobulin antibodies and anti-microsomal antibodies, benign cytology, refused or ineligible for surgery or other conventional treatment Exclusion: history of neck radiation and surgery
LA	Magri et al. (2020) [6]	Jan 2010 to Jan 2013	Istituti Clinici Scientifci Maugeri IRCCS, Italy	43	55.9	5:38	Retro.	43	Inclusion: symptomatic or cosmetic problems, single or dominant nodule, benign cytology (TIR 2) Exclusion: NA
LA	Negro et al. (2019) [7]	Jul 2009 to Mar 2012	V. Fazzi Hospital, Italy	62	54.7	15:47	Retro.	62	Inclusion: symptomatic or cosmetic problems, 2 consecutive benign cytology results, cold nodule, normal thyroid function, normal calcitonin Exclusion: history of thyroid treatment, thyroid hormone-related drug treatment, history of neck radiation
LA	Papini et al. (2014) [8]	Unclear, over 1 year	Multicenter, Italyb	101	51.5	16:85	Pro.	101	Inclusion: solid, 2 consecutive benign cytology results, normal thyroid function, cold nodule, maximum diameter >30 mm, volume of 6–17 mL Exclusion: autoimmunity, previous thyroid gland treatment, thyroid hormone-related drug treatment, history of neck radiation
LA	Valcavi et al. (2010) [9]	Jan 2004 to Dec 2006	Arcispedale Santa Maria Nuova, Italy	122	52.2	27:95	Retro.	122	Inclusion: symptomatic or cosmetic problems, 2 consecutive benign cytology results, single or dominant nodule, solid or mixed (<20% cystic components), size of 2.5–90 mL, diameter >1.5 cm and <7 cm, cold nodule, normal thyroid function, normal calcitonin, no malignant feature on US, normal platelet count and blood coagulation tests Exclusion: family history of thyroid cancer, history of neck radiation and surgery

RFA, radiofrequency ablation; Retro., retrospective; Pro., prospective; US, ultrasonography; NA, not available; LA, laser ablation.

^aAsan Medical Center, Seoul St. Mary’s Hospital, Daerim St. Mary’s Hospital, Seoul National University Hospital, Human Medical Imaging and Intervention Center, Korea;

^bRegina Apostolorum Hospital, University of Pisa, University of Perugia, Catholic University “Sacro Cuore”, Regina Apostolorum Hospital, Italy.